DDD is a graphical front-end for GDB and other command-line debuggers.
This is the First Edition of Debugging with DDD, 8 Feb, 2009, for DDD Version 3.3.12.
Copyright © 2004 Universität des Saarlandes
Lehrstuhl Softwaretechnik
Postfach 15 11 50
66041 Saarbrücken
GERMANY
Distributed by
Free Software Foundation, Inc.
59 Temple Place - Suite 330
Boston, MA 02111-1307
USA
DDD and this manual are available via the DDD WWW page.
Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.1 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts and no Back-Cover Texts. A copy of the license is included in the section entitled “GNU Free Documentation License”; See Documentation License, for details.
Send questions, comments, suggestions, etc. to ddd@gnu.org.
Submit bug reports at http://savannah.gnu.org/bugs/?group=ddd,
the DDD bug tracker. Incoming bug reports are automatically copied
to the developers' mailing list bug-ddd@gnu.org.
The purpose of a debugger such as DDD is to allow you to see what is going on “inside” another program while it executes—or what another program was doing at the moment it crashed.
DDD can do four main kinds of things (plus other things in support of these) to help you catch bugs in the act:
Technically speaking, DDD is a front-end to a command-line debugger (called inferior debugger, because it lies at the layer beneath DDD). DDD supports the following inferior debuggers:
pydb. To get this, see
http://bashdb.sourceforge.net/pydb.
See Choosing an Inferior Debugger, for choosing the appropriate inferior debugger. See Sample Session, for getting a first impression of DDD.
This manual comes in several formats:
The DDD source distribution
ddd-3.3.12.tar.gz contains this manual as
pre-formatted info files; you can also download them from
the DDD WWW page.
The DDD source distribution
ddd-3.3.12.tar.gz contains this manual as
pre-formatted PostScript file; you can also download it from
the DDD WWW page.
The DDD source distribution
ddd-3.3.12.tar.gz contains this manual as
pre-formatted PDF file; you can also download it from
the DDD WWW page.
A pre-formatted HTML version of this manual comes
in a separate DDD package
ddd-3.3.12-html-manual.tar.gz; you can browse
and download it via
the DDD WWW page.
The manual itself is written in TeXinfo format; its source code ddd.texi is contained in the DDD source distribution ddd-3.3.12.tar.gz.
The picture sources come in a separate package ddd-3.3.12-pics.tar.gz; you need this package only if you want to re-create the PostScript, HTML, or PDF versions.
argc - 1$(gdb) _Here's an example. ‘break location’ is a typed command
at the ‘(gdb) ’ prompt; the metasyntactic variable
‘location’ would be replaced by the actual location.
‘_’ is the cursor position after entering the command.
(gdb) break location
Breakpoint number at location
(gdb) _
DDD is free; this means that everyone is free to use it and free to redistribute it on a free basis. DDD is not in the public domain; it is copyrighted and there are restrictions on its distribution, but these restrictions are designed to permit everything that a good cooperating citizen would want to do. What is not allowed is to try to prevent others from further sharing any version of DDD that they might get from you. The precise conditions are found in the GNU General Public License that comes with DDD; See License, for details.
The easiest way to get a copy of DDD is from someone else who has it. You need not ask for permission to do so, or tell any one else; just copy it.
If you have access to the Internet, you can get the latest version of DDD from the anonymous FTP server ‘ftp.gnu.org’ in the directory /gnu/ddd. This should contain the following files:
DDD can also be found at numerous other archive sites around the world; check the file ANNOUNCE in a DDD distribution for the latest known list.
Dorothea Lütkehaus and Andreas Zeller were the original authors of DDD. Many others have contributed to its development. The files ChangeLog and THANKS in the DDD distribution approximates a blow-by-blow account.
The history of DDD is a story of code recycling. The oldest parts of DDD were written in 1990, when Andreas Zeller designed VSL, a box-based visual structure language for visualizing data and program structures. The VSL interpreter and the Box library became part of Andreas' Diploma Thesis, a graphical syntax editor based on the Programming System Generator PSG.
In 1992, the VSL and Box libraries were recycled for the NORA project. For NORA, an experimental inference-based software development tool set, Andreas wrote a graph editor (based on VSL and the Box libraries) and facilities for inter-process knowledge exchange. Based on these tools, Dorothea Lütkehaus (now Dorothea Krabiell) realized DDD as her Diploma Thesis, 1994.
The original DDD had no source window; this was added by Dorothea during the winter of 1994–1995. In the first quarter of 1995, finally, Andreas completed DDD by adding command and execution windows, extensions for DBX and remote debugging as well as configuration support for several architectures. Since then, Andreas has further maintained and extended DDD, based on the comments and suggestions of several DDD users around the world. See the comments in the DDD source for details.
Major DDD events:
You can use this manual at your leisure to read all about DDD. However, a handful of features are enough to get started using the debugger. This chapter illustrates those features.
The sample program sample.c (see Sample Program) exhibits the following bug. Normally, sample should sort and print its arguments numerically, as in the following example:
$ ./sample 8 7 5 4 1 3
1 3 4 5 7 8
$ _
However, with certain arguments, this goes wrong:
$ ./sample 8000 7000 5000 1000 4000
1000 1913 4000 5000 7000
$ _
Although the output is sorted and contains the right number of
arguments, some arguments are missing and replaced by bogus numbers;
here, 8000 is missing and replaced by
1913.3
Let us use DDD to see what is going on. First, you must compile sample.c for debugging (see Compiling for Debugging), giving the -g flag while compiling:
$ gcc -g -o sample sample.c
$ _
Now, you can invoke DDD (see Invocation) on the sample executable:
$ ddd sample
After a few seconds, DDD comes up. The Source Window contains the source of your debugged program; use the Scroll Bar to scroll through the file.
The Debugger Console (at the bottom) contains DDD version information as well as a GDB prompt.4
GNU DDD Version 3.3.12, by Dorothea Lütkehaus and Andreas Zeller.
Copyright © 1995-1999 Technische Universität Braunschweig, Germany.
Copyright © 1999-2001 Universität Passau, Germany.
Copyright © 2001-2004 Universität des Saarlandes, Germany.
Reading symbols from sample...done.
(gdb) _
The first thing to do now is to place a Breakpoint
(see Breakpoints), making sample stop at a location you are
interested in. Click on the blank space left to the initialization of
a. The Argument field ‘():’ now contains the location
(‘sample.c:31’). Now, click on ‘Break’ to create a breakpoint
at the location in ‘()’. You see a little red stop sign appear in
line 31.
The next thing to do is to actually execute the program, such that you can examine its behavior (see Running). Select ‘Program Run’ to execute the program; the ‘Run Program’ dialog appears.
In ‘Run with Arguments’, you can now enter arguments for the sample program. Enter the arguments resulting in erroneous behavior here—that is, ‘8000 7000 5000 1000 4000’. Click on ‘Run’ to start execution with the arguments you just entered.
GDB now starts sample. Execution stops after a few moments as the breakpoint is reached. This is reported in the debugger console.
(gdb) break sample.c:31
Breakpoint 1 at 0x8048666: file sample.c, line 31.
(gdb) run 8000 7000 5000 1000 4000
Starting program: sample 8000 7000 5000 1000 4000
Breakpoint 1, main (argc=6, argv=0xbffff918) at sample.c:31
(gdb) _
The current execution line is indicated by a green arrow.
a = (int *)malloc((argc - 1) * sizeof(int));
You can now examine the variable values. To examine a simple variable,
you can simply move the mouse pointer on its name and leave it there.
After a second, a small window with the variable value pops up
(see Value Tips). Try this with ‘argc’ to see its value
(6). The local variable ‘a’ is not yet initialized; you'll
probably see 0x0 or some other invalid pointer value.
To execute the current line, click on the ‘Next’ button on the command tool. The arrow advances to the following line. Now, point again on ‘a’ to see that the value has changed and that ‘a’ has actually been initialized.
To examine the individual values of the ‘a’ array, enter ‘a[0]’ in the argument field (you can clear it beforehand by clicking on ‘():’) and then click on the ‘Print’ button. This prints the current value of ‘()’ in the debugger console (see Printing Values). In our case, you'll get
(gdb) print a[0]
$1 = 0
(gdb) _
or some other value (note that ‘a’ has only been allocated, but the contents have not yet been initialized).
To see all members of ‘a’ at once, you must use a special GDB
operator. Since ‘a’ has been allocated dynamically, GDB does not
know its size; you must specify it explicitly using the ‘@’
operator (see Array Slices). Enter ‘a[0]@(argc - 1)’ in the
argument field and click on the ‘Print’ button. You get the first
argc - 1 elements of ‘a’, or
(gdb) print a[0]@(argc - 1)
$2 = {0, 0, 0, 0, 0}
(gdb) _
Rather than using ‘Print’ at each stop to see the current value of ‘a’, you can also display ‘a’, such that its is automatically displayed. With ‘a[0]@(argc - 1)’ still being shown in the argument field, click on ‘Display’. The contents of ‘a’ are now shown in a new window, the Data Window. Click on ‘Rotate’ to rotate the array horizontally.
Now comes the assignment of ‘a’'s members:
for (i = 0; i < argc - 1; i++)
a[i] = atoi(argv[i + 1]);
You can now click on ‘Next’ and ‘Next’ again to see how the individual members of ‘a’ are being assigned. Changed members are highlighted.
To resume execution of the loop, use the ‘Until’ button. This makes GDB execute the program until a line greater than the current is reached. Click on ‘Until’ until you end at the call of ‘shell_sort’ in
shell_sort(a, argc);
At this point, ‘a’'s contents should be ‘8000 7000 5000 1000 4000’. Click again on ‘Next’ to step over the call to ‘shell_sort’. DDD ends in
for (i = 0; i < argc - 1; i++)
printf("%d ", a[i]);
and you see that after ‘shell_sort’ has finished, the contents of ‘a’ are ‘1000, 1913, 4000, 5000, 7000’—that is, ‘shell_sort’ has somehow garbled the contents of ‘a’.
To find out what has happened, execute the program once again. This time, you do not skip through the initialization, but jump directly into the ‘shell_sort’ call. Delete the old breakpoint by selecting it and clicking on ‘Clear’. Then, create a new breakpoint in line 35 before the call to ‘shell_sort’. To execute the program once again, select ‘Program Run Again’.
Once more, DDD ends up before the call to ‘shell_sort’:
shell_sort(a, argc);
This time, you want to examine closer what ‘shell_sort’ is doing. Click on ‘Step’ to step into the call to ‘shell_sort’. This leaves your program in the first executable line, or
int h = 1;
while the debugger console tells us the function just entered:
(gdb) step
shell_sort (a=0x8049878, size=6) at sample.c:9
(gdb) _
This output that shows the function where ‘sample’ is now suspended (and its arguments) is called a stack frame display. It shows a summary of the stack. You can use ‘Status Backtrace’ to see where you are in the stack as a whole; selecting a line (or clicking on ‘Up’ and ‘Down’) will let you move through the stack. Note how the ‘a’ display disappears when its frame is left.
Let us now check whether ‘shell_sort’'s arguments are correct. After returning to the lowest frame, enter ‘a[0]@size’ in the argument field and click on ‘Print’:
(gdb) print a[0] @ size
$4 = {8000, 7000, 5000, 1000, 4000, 1913}
(gdb) _
Surprise! Where does this additional value 1913 come from? The
answer is simple: The array size as passed in ‘size’ to
‘shell_sort’ is too large by one—1913 is a bogus
value which happens to reside in memory after ‘a’. And this last
value is being sorted in as well.
To see whether this is actually the problem cause, you can now assign the correct value to ‘size’ (see Assignment). Select ‘size’ in the source code and click on ‘Set’. A dialog pops up where you can edit the variable value.
Change the value of ‘size’ to
5 and click on ‘OK’.
Then, click on ‘Finish’ to resume execution of the
‘shell_sort’ function:
(gdb) set variable size = 5
(gdb) finish
Run till exit from #0 shell_sort (a=0x8049878, size=5) at sample.c:9
0x80486ed in main (argc=6, argv=0xbffff918) at sample.c:35
(gdb) _
Success! The ‘a’ display now contains the correct values ‘1000, 4000, 5000, 7000, 8000’.
You can verify that these values are actually printed to standard output by further executing the program. Click on ‘Cont’ to continue execution.
(gdb) cont
1000 4000 5000 7000 8000
Program exited normally.
(gdb) _
The message ‘Program exited normally.’ is from GDB; it indicates that the sample program has finished executing.
Having found the problem cause, you can now fix the source code. Click on ‘Edit’ to edit sample.c, and change the line
shell_sort(a, argc);
to the correct invocation
shell_sort(a, argc - 1);
You can now recompile sample
$ gcc -g -o sample sample.c
$ _
and verify (via ‘Program Run Again’) that sample works fine now.
(gdb) run
`sample' has changed; re-reading symbols.
Reading in symbols...done.
Starting program: sample 8000 7000 5000 1000 4000
1000 4000 5000 7000 8000
Program exited normally.
(gdb) _
All is done; the program works fine now. You can end this DDD session with ‘Program Exit’ or Ctrl+Q.
Here's the source sample.c of the sample program.
| /* sample.c -- Sample C program to be debugged with DDD */ #include <stdio.h> #include <stdlib.h> static void shell_sort(int a[], int size) { int i, j; int h = 1; do { h = h * 3 + 1; } while (h <= size); do { h /= 3; for (i = h; i < size; i++) { int v = a[i]; for (j = i; j >= h && a[j - h] > v; j -= h) a[j] = a[j - h]; if (i != j) a[j] = v; } } while (h != 1); } int main(int argc, char *argv[]) { int *a; int i; a = (int *)malloc((argc - 1) * sizeof(int)); for (i = 0; i < argc - 1; i++) a[i] = atoi(argv[i + 1]); shell_sort(a, argc); for (i = 0; i < argc - 1; i++) printf("%d ", a[i]); printf("\n"); free(a); return 0; } |
This chapter discusses how to start DDD, and how to get out of it. The essentials are:
Normally, you can run DDD by invoking the program ddd.
You can also run DDD with a variety of arguments and options, to specify more of your debugging environment at the outset.
The most usual way to start DDD is with one argument, specifying an executable program:
ddd program
If you use GDB, DBX, Ladebug, or XDB as inferior debuggers, you can also start with both an executable program and a core file specified:
ddd program core
You can, instead, specify a process ID as a second argument, if you want to debug a running process:
ddd program 1234
would attach DDD to process 1234 (unless you also have a file
named 1234; DDD does check for a core file first).
You can further control DDD by invoking it with specific options. To get a list of DDD options, invoke DDD as
ddd --help
Most important are the options to specify the inferior debugger (see Choosing an Inferior Debugger), but you can also customize several aspects of DDD upon invocation (see Options).
DDD also understands the usual X options such as -display or -geometry. See X Options, for details.
All arguments and options that are not understood by DDD are passed to the inferior debugger; See Inferior Debugger Options, for a survey. To pass an option to the inferior debugger that conflicts with an X option, or with a DDD option listed here, use the --debugger option (see Options).
The most frequently required options are those to choose a specific inferior debugger.
Normally, the inferior debugger is determined by the program to analyze:
pydb, Bash, or inferior debugger.
Use
ddd --bash program
ddd --interpreter='path-to-debugger-bash --debugger' program
ddd --jdb program
ddd --make program
ddd --interpreter='path-to-debugger-make --debugger' program
ddd --perl program
ddd --pydb program
to run DDD with JDB, pydb, Perl, Bash, or GNU Make as an inferior
debugger.
Use
ddd --dbx program
ddd --gdb program
ddd --ladebug program
ddd --wdb program
ddd --xdb program
to run DDD with GDB, WDB, DBX, Ladebug, or XDB as inferior debugger.
If you invoke DDD without any of these options, but give a program to analyze, then DDD will automatically determine the inferior debugger:
See Customizing Debugger Interaction, for more details on determining the inferior debugger.
You can further control how DDD starts up using the following options. All options may be abbreviated, as long as they are unambiguous; single dashes - instead of double dashes -- may also be used. Almost all options control a specific DDD resource or resource class (see Customizing).
Giving this option is equivalent to setting the DDD
‘Separate’ resource class to ‘off’. See Window Layout, for
details.
Giving this option is equivalent to setting the DDD
‘separateSourceWindow’ resource to ‘off’.
See Window Layout, for details.
Giving this option is equivalent to setting the DDD
‘separateDataWindow’ resource to ‘off’. See Window Layout,
for details.
Giving this option is equivalent to setting the DDD
‘autoDebugger’ resource to ‘on’.
See Customizing Debugger Interaction, for details.
Giving this option is equivalent to setting the DDD
‘buttonTips’ resource to ‘on’. See Customizing Help, for
details.
Giving this option is equivalent to setting the DDD
‘showConfiguration’ resource to ‘on’. See Diagnostics, for
details.
Giving this option is equivalent to setting the DDD
‘checkConfiguration’ resource to ‘on’. See Diagnostics,
for details.
Giving this option is equivalent to setting the DDD
‘openDataWindow’ resource to ‘on’. See Toggling Windows,
for details.
Giving this option is equivalent to setting the DDD
‘debugger’ resource to ‘dbx’.
See Customizing Debugger Interaction, for details.
This option can also be used to pass options to the inferior debugger that would otherwise conflict with DDD options. For instance, to pass the option -d directory to XDB, use:
ddd --debugger "xdb -d directory"
If you use the --debugger option, be sure that the type of inferior debugger is specified as well. That is, use one of the options --gdb, --dbx, --xdb, --jdb, --pydb, or --perl (unless the default setting works fine).
Giving this option is equivalent to setting the DDD
‘debuggerCommand’ resource to name. See Customizing Debugger Interaction, for details.
Giving this option is equivalent to setting the DDD
‘openDebuggerConsole’ resource to ‘on’. See Toggling Windows, for details.
Giving this option is equivalent to setting the DDD
‘disassemble’ resource to ‘on’. See Customizing Source,
for details.
Giving this option is equivalent to setting the DDD
‘separateExecWindow’ resource to ‘on’. See Customizing the Execution Window, for details.
Giving this option is equivalent to setting the DDD
‘defaultFont’ resource to ‘fontname’. See Customizing Fonts, for details.
Giving this option is equivalent to setting the DDD
‘showFonts’ resource to ‘on’. See Diagnostics, for
details.
Giving this option is equivalent to setting the DDD
‘FontSize’ resource class to ‘size’. See Customizing Fonts, for details.
Giving this option is equivalent to setting the DDD
‘TTYMode’ resource class to ‘on’. See TTY mode, for
details.
Giving this option is equivalent to setting the DDD
‘debugger’ resource to ‘gdb’. See Customizing Debugger Interaction,
for details.
Giving this option is equivalent to setting the DDD
‘displayGlyphs’ resource to ‘on’. See Customizing Source,
for details.
Giving this option is equivalent to setting the DDD
‘showInvocation’ resource to ‘on’. See Diagnostics, for
details.
Giving this option is equivalent to setting the DDD
‘debuggerHost’ resource to hostname. See Remote Debugger,
for details.
Giving this option is equivalent to setting the DDD
‘debugger’ resource to ‘jdb’. See Customizing Debugger Interaction,
for details.
Giving this option is equivalent to setting the DDD
‘debugger’ resource to ‘ladebug’. See Customizing Debugger Interaction, for details.
Giving this option is equivalent to setting the DDD
‘lessTifVersion’ resource to 999. See LessTif, for
details.
Giving this option is equivalent to setting the DDD
‘lessTifVersion’ resource to version. See LessTif, for
details.
Giving this option is equivalent to setting the DDD
‘showLicense’ resource to on. See Diagnostics, for
details.
Giving this option is equivalent to setting the DDD
‘debuggerHostLogin’ resource to username. See Remote Debugger, for details.
Giving this option is equivalent to setting the DDD
‘maintenance’ resource to on. See Maintenance Menu, for
details.
Giving this option is equivalent to setting the DDD
‘showManual’ resource to on. See Diagnostics, for
details.
Giving this option is equivalent to setting the DDD
‘showNews’ resource to on. See Diagnostics, for details.
Giving this option is equivalent to setting the DDD
‘buttonTips’ resource to ‘off’. See Customizing Help, for
details.
Giving this option is equivalent to setting the DDD
‘openDataWindow’ resource to ‘off’. See Toggling Windows,
for details.
Giving this option is equivalent to setting the DDD
‘openDebuggerConsole’ resource to ‘off’. See Toggling Windows, for details.
Giving this option is equivalent to setting the DDD
‘disassemble’ resource to ‘off’. See Customizing Source,
for details.
Giving this option is equivalent to setting the DDD
‘separateExecWindow’ resource to ‘off’. See Customizing the Execution Window, for details.
Giving this option is equivalent to setting the DDD
‘displayGlyphs’ resource to ‘off’. See Customizing Source,
for details.
Giving this option is equivalent to setting the DDD
‘lessTifVersion’ resource to 1000. See LessTif, for
details.
Giving this option is equivalent to setting the DDD
‘maintenance’ resource to off. See Maintenance Menu, for
details.
Giving this option is equivalent to setting the DDD
‘openSourceWindow’ resource to ‘off’. See Toggling Windows, for details.
Giving this option is equivalent to setting the DDD
‘valueTips’ resource to ‘off’. See Value Tips, for
details.
Giving this option is equivalent to setting the DDD
‘debugger’ resource to ‘perl’. See Customizing Debugger Interaction,
for details.
pydb as inferior debugger.
Giving this option is equivalent to setting the DDD
‘debugger’ resource to ‘pydb’. See Customizing Debugger Interaction,
for details.
Giving this option is equivalent to setting the DDD
‘pannedGraphEditor’ resource to ‘on’. See Display Resources, for details.
ddd --play-log log-file
invokes DDD as inferior debugger, simulating the inferior debugger given in log-file (see below). This is useful for debugging DDD.
Giving this option is equivalent to setting the DDD
‘playLog’ resource to ‘on’. See Customizing Debugger Interaction, for
details.
Giving this option is equivalent to setting the DDD
‘debuggerRHost’ resource to hostname. See Remote Debugger, for details.
Giving this option is equivalent to setting the DDD
‘pannedGraphEditor’ resource to ‘off’. See Display Resources, for details.
Giving this option is equivalent to setting the DDD
‘Separate’ resource class to ‘off’. See Window Layout, for
details.
Giving this option is equivalent to setting the DDD
‘session’ resource to session. See Resuming Sessions, for
details.
Giving this option is equivalent to setting the DDD
‘openSourceWindow’ resource to ‘on’. See Toggling Windows,
for details.
Giving this option is equivalent to setting the DDD
‘statusAtBottom’ resource to ‘on’. See Window Layout, for
details.
Giving this option is equivalent to setting the DDD
‘statusAtBottom’ resource to ‘off’. See Window Layout, for
details.
Giving this option is equivalent to setting the DDD
‘synchronousDebugger’ resource to ‘on’. See Customizing Debugger Interaction, for details.
Giving this option is equivalent to setting the DDD
‘toolbarsAtBottom’ resource to ‘on’. See Window Layout,
for details.
Giving this option is equivalent to setting the DDD
‘toolbarsAtBottom’ resource to ‘off’. See Window Layout,
for details.
Giving this option is equivalent to setting the DDD ‘trace’
resource to on. See Diagnostics, for details.
Giving this option is equivalent to setting the DDD
‘ttyMode’ resource to ‘on’. See TTY mode, for details.
Giving this option is equivalent to setting the DDD
‘valueTips’ resource to ‘on’. See Value Tips, for details.
Giving this option is equivalent to setting the DDD
‘showVersion’ resource to ‘on’. See Diagnostics, for
details.
Giving this option is equivalent to setting the DDD ‘vslLibrary’
resource to library. See VSL Resources, for details.
Giving this option is equivalent to setting the DDD ‘vslPath’
resource to path. See VSL Resources, for details.
Giving this option is equivalent to setting the DDD
‘debugger’ resource to ‘wdb’. See Customizing Debugger Interaction, for details.
Giving this option is equivalent to setting the DDD ‘debugger’ resource to ‘xdb’. See Customizing Debugger Interaction, for details.
DDD also understands the following X options. Note that these options only take a single dash -.
All options that DDD does not recognize are passed to the inferior debugger. This section lists the most useful options of the different inferior debuggers supported by DDD. In case these options do not work as expected, please lookup the appropriate reference.
These GDB options are useful when using DDD with GDB as inferior debugger. Single dashes - instead of double dashes -- may also be used.
See Invoking GDB, for further options that can be used with GDB.
DBX variants differ widely in their options, so we cannot give a list here. Check out the dbx(1) and ladebug(1) manual pages.
These XDB options are useful when using DDD with XDB as inferior debugger.
Further options can be found in the xdb(1) manual page.
The following JDB options are useful when using DDD with JDB (from JDK 1.2) as inferior debugger.
These JDB options are forwarded to the debuggee:
The following JDB options are useful when using DDD with JDB (from JDK 1.1) as inferior debugger.
These JDB options are forwarded to the debuggee:
Further options can be found in the JDB documentation.
If you have the proper bash installed, the option needed to specify debugging support is --debugger. If your bash doesn't understand this option you need to pick up a version of bash that does from http://bashdb.sourceforge.net. Other options can be found from the on-line documentation at http://bashdb.sourceforge.net/bashdb.html
If you have the proper make installed (for now it is probably
called remake), the option needed to specify debugging support
is --debugger. You can pick up a debugger-enabled version
from http://bashdb.sourceforge.net/remake. Other options can be
found from the on-line documentation at
http://bashdb.sourceforge.net/remake/mdb.html
The most important Perl option to use with DDD is -w; it enables several important warnings. For further options, see the perlrun(1) manual page.
An older version of pydb used to come with DDD. That is no
longer the case. Pick up the newer version of pydb from
http://bashdb.sourceforge.net/pydb. For a list of useful
pydb options, check out the pydb documentation,
http://bashdb.sourceforge.net/pydb/pydb/lib/index.html.
If you have multiple DDD instances running, they share common preferences and history files. This means that changes applied to one instance may get lost when being overwritten by the other instance. DDD has two means to protect you against unwanted losses. The first means is an automatic reloading of changed options, controlled by the following resource (see Customizing):
Every n seconds, where n is the value of this resource, DDD checks whether the options file has changed. Default is
30, which means that every 30 seconds, DDD checks for the options file. Setting this resource to0disables checking for changed option files.
Normally, automatic reloading of options should already suffice. If you need stronger protection, DDD also provides a warning against multiple instances. This warning is disabled by default, If you want to be warned about multiple DDD invocations sharing the same preferences and history files, enable ‘Edit Preferences Warn if Multiple DDD Instances are Running’.
This setting is tied to the following resource (see Customizing):
Whether to warn if multiple DDD instances are running (‘on’) or not (‘off’, default).
If you are bothered by X warnings, you can suppress them by setting ‘Edit Preferences General Suppress X warnings’.
This setting is tied to the following resource (see Customizing):
If ‘on’, X warnings are suppressed. This is sometimes useful for executables that were built on a machine with a different X or M*tif configuration. By default, this is ‘off’.
To exit DDD, select ‘File Exit’. You may also type the quit command at the debugger prompt or press <Ctrl+Q>. GDB and XDB also accept the q command or an end-of-file character (usually <Ctrl+D>). Closing the last DDD window will also exit DDD.
An interrupt (<ESC> or ‘Interrupt’) does not exit from DDD, but rather terminates the action of any debugger command that is in progress and returns to the debugger command level. It is safe to type the interrupt character at any time because the debugger does not allow it to take effect until a time when it is safe.
In case an ordinary interrupt does not succeed, you can also use an
abort (<Ctrl+\> or ‘Abort’), which sends a SIGABRT
signal to the inferior debugger. Use this in emergencies only; the
inferior debugger may be left inconsistent or even exit after a
SIGABRT signal.
As a last resort (if DDD hangs, for example), you may also
interrupt DDD itself using an interrupt signal (SIGINT).
This can be done by typing the interrupt character (usually
<Ctrl+C>) in the shell DDD was started from, or by using the
UNIX ‘kill’ command. An interrupt signal interrupts any
DDD action; the inferior debugger is interrupted as well. Since
this interrupt signal can result in internal inconsistencies, use this
as a last resort in emergencies only; save your work as soon as possible
and restart DDD.
If you want to interrupt your current DDD session, you can save the entire the entire DDD state as session on disk and resume later.
To save a session, select ‘File Save Session As’. You will be asked for a symbolic session name session.
If your program is running (see Running), or if you have opened a core file (see Opening Core Dumps), DDD can also include a core file in the session such that the debuggee data will be restored when re-opening it. To get a core file, DDD typically must kill the debuggee. This means that you cannot resume program execution after saving a session. Depending on your architecture, other options for getting a core file may also be available.
Including a core dump is necessary for restoring memory contents and the current execution position. To include a core dump, enable ‘Include Core Dump’.
After clicking on ‘Save’, the session is saved in ~/.ddd/sessions/session.
Here's a list of the items whose state is saved in a session:
After saving the current state as a session, the session becomes active. This means that DDD state will be saved as session defaults:
To make the current session inactive, open the default session named ‘[None]’. See Resuming Sessions, for details on opening sessions.
To resume a previously saved session, select ‘File Open Session’ and choose a session name from the list. After clicking on ‘Open’, the entire DDD state will be restored from the given session.
The session named ‘[None]’ is the default session which is active when starting DDD. To save options for default sessions, choose the default session before exiting DDD. See Saving Options, for details.
If a the restored session includes a core dump, the program being debugged will be in the same state at the time the session was saved; in particular, you can examine the program data. However, you will not be able to resume program execution since the process and its environment (open files, resources, etc.) no longer exist. However, you can restart the program, re-using the restored breakpoints and data displays.
Opening sessions also restores command definitions, buttons, display shortcuts and the source tab width. This way, you can maintain a different set of definitions for each session.
You can also specify a session to open when starting DDD. To invoke DDD with a session session, use
ddd --session session
There is also a shortcut that opens the session session and invokes the inferior debugger on an executable named session (in case session cannot be opened):
ddd =session
There is no need to give further command-line options when restarting a session, as they will be overridden by the options saved in the session.
You can also use an X session manager such as xsm to save and restore DDD sessions.7 When being shut down by a session manager, DDD saves its state under the name specified by the session manager; resuming the X session makes DDD reload its saved state.
To delete sessions that are no longer needed, select ‘File Open Session’ or ‘File Save Session’. Select the sessions you want to delete and click on ‘Delete’.
The default session ‘[None]’ cannot be deleted.
You can change the place where DDD saves its sessions by setting the environment variable DDD_SESSIONS to the name of a directory. Default is ~/.ddd/sessions/.
Where applicable, DDD supports a gcore command to obtain core files of the running program. You can enter its path via ‘Edit Preferences Helpers Get Core File’. Leave the value empty if you have no gcore or similar command.
This setting is tied to the following resource (see Customizing):
A command to get a core dump of a running process (typically, gcore) ‘@FILE@’ is replaced by the base name of the file to create; ‘@PID@’ is replaced by the process id. The output must be written to ‘@FILE@.@PID@’.
Leave the value empty if you have no gcore or similar command.
You can have each of DDD, the inferior debugger, and the debugged program run on different machines.
You can run DDD on a remote host, using your current host as X display. On the remote host, invoke DDD as
ddd -display display
where display is the name of the X server to connect to (for instance, ‘hostname:0.0’, where hostname is your host).
Instead of specifying -display display, you can also set the DISPLAY environment variable to display.
In order to run the inferior debugger on a remote host, you need ‘remsh’ (called ‘rsh’ on BSD systems) access on the remote host.
To run the debugger on a remote host hostname, invoke DDD as
ddd --host hostname remote-program
If your remote username differs from the local username, use
ddd --host hostname --login username remote-program
or
ddd --host username@hostname remote-program
instead.
There are a few caveats in remote mode:
Note: using --rhost, DDD invokes the inferior debugger as soon as a shell prompt appears. The first output on the remote host ending in a space character or ‘>’ and not followed by a newline is assumed to be a shell prompt. If necessary, adjust your shell prompt on the remote host.
See Customizing Remote Debugging, for customizing remote mode.
When having the inferior debugger run on a remote host (see Remote Debugging), all commands to access the inferior debugger as well as its files must be run remotely. This is controlled by the following resources (see Customizing):
The remote shell command to invoke TTY-based commands on remote hosts. Usually, remsh, rsh, ssh, or on.
The command to list all core files on the remote host. The string ‘@MASK@’ is replaced by a file filter. The default setting is:
Ddd*listCoreCommand: \ file @MASK@ | grep '.*:.*core.*' | cut -d: -f1
The command to list all directories on the remote host. The string ‘@MASK@’ is replaced by a file filter. The default setting is:
Ddd*listDirCommand: \ file @MASK@ | grep '.*:.*directory.*' | cut -d: -f1
The command to list all executable files on the remote host. The string ‘@MASK@’ is replaced by a file filter. The default setting is:
Ddd*listExecCommand: \ file @MASK@ | grep '.*:.*exec.*' \ | grep -v '.*:.*script.*' \ | cut -d: -f1 | grep -v '.*\.o$'
The command to list all source files on the remote host. The string ‘@MASK@’ is replaced by a file filter. The default setting is:
Ddd*listSourceCommand: \ file @MASK@ | grep '.*:.*text.*' | cut -d: -f1
The GDB debugger allows you to run the debugged program on a remote machine (called remote target), while GDB runs on the local machine.
See Remote Debugging, for details. Basically, the following steps are required:
The local .gdbinit file is useful for setting up directory search paths, etc.
Of course, you can also combine DDD remote mode and GDB remote mode, running DDD, GDB, and the debugged program each on a different machine.
These settings control the interaction of DDD with its inferior debugger.
To choose the default inferior debugger, select ‘Edit Preferences Startup Debugger Type’. You can
The following DDD resources control the invocation of the inferior debugger (see Customizing).
If this is ‘on’ (default), DDD will attempt to determine the debugger type from its arguments, possibly overriding the ‘debugger’ resource (see below). If this is ‘off’, DDD will invoke the debugger specified by the ‘debugger’ resource regardless of DDD arguments.
The type of the inferior debugger to invoke (‘bash’ ‘dbx’, ‘gdb’, ‘jdb’, ‘ladebug’, ‘make’, ‘perl’, ‘pydb’, or ‘xdb’).
This resource is usually set through the --bash, --dbx, --gdb, --jdb, --ladebug, --make, --perl, --pydb, and --xdb, options; See Options, for details.
The name under which the inferior debugger is to be invoked. If this string is empty (default), the debugger type (‘debugger’ resource) is used.
This resource is usually set through the --debugger option; See Options, for details.
DDD uses a number of resources to initialize the inferior debugger (see Customizing).
This string contains a list of newline-separated commands that are initially sent to the Bash debugger. By default, it is empty.
This resource may be used to customize the Bash debugger.
This string contains a list of newline-separated commands that are also initially sent to the Bash debugger. By default, it is empty.
This resource is used by DDD to save and restore Bash debugger settings.
This string contains a list of newline-separated commands that are initially sent to DBX. By default, it is empty.
Do not use this resource to customize DBX; instead, use a personal ~/.dbxinit or ~/.dbxrc file. See your DBX documentation for details.
This string contains a list of newline-separated commands that are also initially sent to DBX. By default, it is empty.
This string contains a list of newline-separated commands that are initially sent to GDB. As a side-effect, all settings specified in this resource are considered fixed and cannot be changed through the GDB settings panel, unless preceded by white space. By default, the ‘gdbInitCommands’ resource contains some settings vital to DDD:
Ddd*gdbInitCommands: \ set height 0\n\ set width 0\n\ set verbose off\n\ set prompt (gdb) \nWhile the ‘set height’, ‘set width’, and ‘set prompt’ settings are fixed, the ‘set verbose’ settings can be changed through the GDB settings panel (although being reset upon each new DDD invocation).
Do not use this resource to customize GDB; instead, use a personal ~/.gdbinit file. See your GDB documentation for details.
This string contains a list of newline-separated commands that are also initially sent to GDB. Its default value is
Ddd*gdbSettings: \ set print asm-demangle on\nThis resource is used to save and restore the debugger settings.
If ‘on’ (default), DDD writes all GDB initialization commands into a temporary file and makes GDB read this file, rather than sending each initialization command separately. This results in faster startup (especially if you have several user-defined commands). If ‘off’, DDD makes GDB process each command separately.
This string contains a list of newline-separated commands that are initially sent to JDB. This resource may be used to customize JDB. By default, it is empty.
This string contains a list of newline-separated commands that are also initially sent to JDB. By default, it is empty.
This resource is used by DDD to save and restore JDB settings.
This string contains a list of newline-separated commands that are initially sent to the Bash debugger. By default, it is empty.
This resource may be used to customize GNU Make debugging.
This string contains a list of newline-separated commands that are also initially sent to the GNU Make debugger. By default, it is empty.
This resource is used by DDD to save and restore GNU Make debugger settings.
This string contains a list of newline-separated commands that are initially sent to the Perl debugger. By default, it is empty.
This resource may be used to customize the Perl debugger.
This string contains a list of newline-separated commands that are also initially sent to the Perl debugger. By default, it is empty.
This resource is used by DDD to save and restore Perl debugger settings.
This string contains a list of newline-separated commands that are initially sent to
pydb. By default, it is empty.This resource may be used to customize
pydb.
This string contains a list of newline-separated commands that are also initially sent to
pydb. By default, it is empty.This resource is used by DDD to save and restore
pydbsettings.
This string contains a list of newline-separated commands that are initially sent to XDB. By default, it is empty.
Do not use this resource to customize DBX; instead, use a personal ~/.xdbrc file. See your XDB documentation for details.
This string contains a list of newline-separated commands that are also initially sent to XDB. By default, it is empty.
When loading an executable, DDD queries the inferior debugger for the initial source location—typically the
mainfunction. If this location is not found, DDD tries other symbols from this newline-separated list. The default value makes DDD look for a variety of main functions (especially FORTRAN main functions):main\n\ MAIN\n\ main_\n\ MAIN_\n\ main__\n\ MAIN__\n\ _main\n\ _MAIN\n\ __main\n\ __MAIN
If this is ‘on’, DDD invoked without argument checks whether the current selection or clipboard contains the file name or URL of an executable program. If this is so, DDD will automatically open this program for debugging. If this resource is ‘off’ (default), DDD invoked without arguments will always start without a debugged program.
The following resources control the communication with the inferior debugger.
Whether DDD should block when reading data from the inferior debugger via the pseudo-tty interface. Most UNIX systems except GNU/Linux require this; set it to ‘on’. On GNU/Linux, set it to ‘off’. The value ‘auto’ (default) will always select the “best” choice (that is, the best choice known to the DDD developers).
If this is ‘on’, all output from the inferior debugger is buffered until a debugger prompt appears. This makes it easier for DDD to parse the output, but has the drawback that interaction with a running debuggee in the debugger console is not possible. If ‘off’, output is shown as soon as it arrives, enabling interaction, but making it harder for DDD to parse the output. If ‘auto’ (default), output is buffered if and only if the execution window is open, which redirects debuggee output and thus enables interaction. See Using the Execution Window, for details.
The time (in ms) to wait before automatically interrupting a ‘cont’ command. DDD cannot interrupt a ‘cont’ command immediately, because this may disturb the status change of the process. Default is
200.
The time (in ms) to wait for the inferior debugger to finish a partial display information. Default is
2000.
The time (in ms) to wait for the inferior debugger to finish a partial position information. Default is
500.
The time (in seconds) to wait for the inferior debugger to reply. Default is
10.
The time (in ms) to wait before automatically interrupting a ‘run’ command. DDD cannot interrupt a ‘cont’ command immediately, because this may disturb process creation. Default is
2000.
If ‘on’ (default), debugger commands interrupt program execution, resuming execution after the command has completed. This only happens if the last debugger command was either a ‘run’ or a ‘continue’ command. If ‘off’, debugger commands do not interrupt program execution.
If ‘on’, X events are not processed while the debugger is busy. This may result in slightly better performance on single-processor systems. See Options, for the --sync-debugger option.
If ‘on’, DDD terminates the inferior debugger when DDD detects an EOF condition (that is, as soon as the inferior debugger closes its output channel). This was the default behavior in DDD 2.x and earlier. If ‘off’ (default), DDD takes no special action.
If ‘on’, use the GDB tty command for redirecting input/output to the separate execution window. If ‘off’, use explicit redirection through shell redirection operators ‘<’ and ‘>’. The default is ‘off’ (explicit redirection), since on some systems, the tty command does not work properly on some GDB versions.
DDD is composed of three main windows. From top to bottom, we have:
Besides these three main windows, there are some other optional windows:
The DDD Menu Bar gives you access to all DDD functions.
FileEditViewProgramCommandsStatusSourceDataMaintenanceHelpThere are two ways of selecting an item from a pull-down menu:
The menus can also be torn off (i.e. turned into a persistent window) by selecting the dashed line at the top.
If a command in the pull-down menu is not applicable in a given situation, the command is disabled and its name appears faded. You cannot invoke items that are faded. For example, many commands on the ‘Edit’ menu appear faded until you select text on which they are to operate; after you select a block of text, edit commands are enabled.
The ‘File’ menu contains file-related operations such as selecting programs, processes, and sessions, printing graphs, recompiling, as well as exiting DDD.
Open ProgramOpen ClassOpen RecentOpen Core DumpOpen SourceOpen SessionSave Session AsAttach to ProcessDetach ProcessPrint GraphChange DirectoryMakemake program (<Ctrl+M>). See Recompiling, for
details.
CloseRestartExitThe ‘Edit’ menu contains standard editing operations, such as cutting, copying, pasting, and killing selected text. Also allows editing DDD options and preferences.
UndoRedoCutThis item can also be applied to displays (see Deleting Displays).
CopyThis item can also be applied to displays (see Deleting Displays).
PasteClearDeleteThis item can also be applied to displays (see Deleting Displays).
Select AllPreferencesDebugger SettingsSave OptionsThe ‘View’ menu allows accessing the individual DDD windows.
Command ToolExecution WindowDebugger ConsoleSource WindowData WindowMachine Code WindowThe ‘Program’ menu performs operations related to the program being debugged, such as starting and stopping the program.
Most of these operations are also found on the command tool (see Command Tool).
RunRun AgainRun in Execution WindowStepStep InstructionNextNext InstructionUntilFinishContinueContinue Without SignalKillInterruptAbortSIGABRT signal to
the process. See Quitting, for details.
The ‘Commands’ menu performs operations related to DDD commands, such as accessing the command history or defining new commands.
Most of these items are not meant to be actually executed via the menu; instead, they serve as reminder for the equivalent keyboard commands.
Command HistoryPreviousNextFind BackwardFind ForwardQuit SearchCompleteApplyClear LineClear WindowDefine CommandEdit ButtonsThe ‘Status’ menu lets you examine the program status, such as the stack traces, registers, or threads.
BacktraceRegistersThreadsSignalsUpDownThe ‘Source’ menu performs source-related operations such as looking up items or editing breakpoints.
BreakpointsLookup ()Find >> ()Find << ()Find Words OnlyFind Case SensitiveDisplay Line NumbersDisplay Machine CodeEdit SourceReload SourceThe ‘Data’ menu performs data-related operations such as editing displays or layouting the display graph.
DisplaysWatchpointsMemoryPrint ()Display ()Detect AliasesDisplay Local VariablesDisplay ArgumentsStatus DisplaysAlign on GridRotate GraphLayout GraphRefreshThe ‘Maintenance’ menu performs operations that are useful for debugging DDD.
By default, this menu is disabled; it is enabled by specifically requesting it at DDD invocation (via the --maintenance option; see Options). It is also enabled when DDD gets a fatal signal.
Debug DDDDump Core NowSIGUSR1 signal.
Tic Tac ToeWhen DDD CrashesDebug DDDDump CoreDo NothingRemove MenuThe ‘Help’ menu gives help on DDD usage. See Getting Help, for a discussion on how to get help within DDD.
OverviewOn ItemOn WindowWhat Now?Tip of the DayDDD ReferenceDDD NewsDebugger ReferenceDDD LicenseDDD WWW PageAbout DDDThe Menu Bar can be customized in various ways (see Customizing).
You can cause pull-down menus to be raised automatically.
If ‘on’ (default), DDD will always keep the pull down menu on top of the DDD main window. If this setting interferes with your window manager, or if your window manager does not auto-raise windows, set this resource to ‘off’.
The time (in ms) during which an initial auto-raised window blocks further auto-raises. This is done to prevent two overlapping auto-raised windows from entering an auto-raise loop. Default is
100.
In the Menu Bar, the ‘Edit’ Menu can be customized in various ways. Use ‘Edit Preferences Startup’ to customize these keys.
The <Ctrl+C> key can be bound to different actions, each in accordance with a specific style guide.
CopyInterruptThe <Ctrl+A> key can be bound to different actions, too.
Select AllBeginning of LineHere are the related DDD resources:
Controls the key bindings for clipboard operations.
- If this is ‘Motif’ (default), Cut/Copy/Paste is on <Shift+Del>/<Ctrl+Ins>/<Shift+Ins>. This is conformant to the M*tif style guide.
- If this is ‘KDE’, Cut/Copy/Paste is on <Ctrl+X>/<Ctrl+C>/<Ctrl+V>. This is conformant to the KDE style guide. Note that this means that <Ctrl+C> no longer interrupts the debuggee; use <ESC> instead.
Controls the key bindings for the ‘Select All’ operation.
- If this is ‘Motif’, Select All is on <Shift+Ctrl+A>.
- If this is ‘KDE’ (default), Select All is on <Ctrl+A>. This is conformant to the KDE style guide. Note that this means that <Ctrl+A> no longer moves the cursor to the beginning of a line; use <Home> instead.
Some DDD commands require an argument. This argument is specified in the argument field, labeled ‘():’. Basically, there are four ways to set arguments:
Using GDB and Perl, the argument field provides a completion mechanism. You can enter the first few characters of an item an press the <TAB> key to complete it. Pressing <TAB> again shows alternative completions.
After having entered an argument, you can select one of the buttons on the right. Most of these buttons also have menus associated with them; this is indicated by a small arrow in the upper right corner. Pressing and holding mouse button 1 on such a button will pop up a menu with further operations.
These are the buttons of the tool bar. Note that not all buttons may be inactive, depending on the current state and the capabilities of the inferior debugger.
LookupFind >>Break/ClearBreakClearWatch/UnwatchWatchUnwatchPrintDisplayPlotShow/HideRotateSetUndispThe DDD tool bar buttons can appear in a variety of styles, customized via ‘Edit Preferences Startup’.
ImagesCaptionsThe default is to have images as well as captions, but you can choose to have only images (saving space) or only captions.
If you choose to have neither images nor captions, tool bar buttons are labeled like other buttons, as in DDD 2.x. Note that this implies that in the stacked window configuration, the common tool bar cannot be displayed; it is replaced by two separate tool bars, as in DDD 2.x.
If you enable ‘Flat’ buttons (default), the border of tool bar buttons will appear only if the mouse pointer is over them. This latest-and-greatest GUI invention can be disabled, such that the button border is always shown.
If you enable ‘Color’ buttons, tool bar images will be colored when entered. If DDD was built using M*tif 2.0 and later, you can also choose a third setting, where buttons appear in color all the time.
Here are the related resources (see Customizing):
The XPM color key to use for the images of active buttons (entered or armed). ‘c’ means color, ‘g’ (default) means grey, and ‘m’ means monochrome.
Whether the tool bar buttons should be shown using captions (‘on’, default) or not (‘off’). If neither captions nor images are enabled, tool bar buttons are shown using ordinary labels. See also ‘buttonImages’, below.
The geometry of the caption subimage within the button icons. Default is ‘29x7+0-0’.
Whether the tool bar buttons should be shown using images (‘on’, default) or not (‘off’). If neither captions nor images are enabled, tool bar buttons are shown using ordinary labels. See also ‘buttonCaptions’, above.
The geometry of the image within the button icon. Default is ‘25x21+2+0’.
The XPM color key to use for the images of inactive buttons (non-entered or insensitive). ‘c’ means color, ‘g’ (default) means grey, and ‘m’ means monochrome.
If ‘on’ (default), all tool bar buttons with images or captions are given a `flat' appearance—the 3-D border only shows up when the pointer is over the icon. If ‘off’, the 3-D border is shown all the time.
If ‘on’ (default), all dialog buttons with images or captions are given a `flat' appearance—the 3-D border only shows up when the pointer is over the icon. If ‘off’, the 3-D border is shown all the time.
The command tool is a small window that gives you access to the most frequently used DDD commands. It can be moved around on top of the DDD windows, but it can also be placed besides them.
By default, the command tool sticks to the DDD source window: Whenever you move the DDD source window, the command tool follows such that the distance between source window and command tool remains the same. By default, the command tool is also auto-raised, such that it stays on top of other DDD windows.
The command tool can be configured to appear as a command tool bar above the source window; see ‘Edit Preferences Source Tool Buttons Location’ for details.
Whenever you save DDD state, DDD also saves the distance between command tool and source window, such that you can select your own individual command tool placement. To move the command tool to its saved position, use ‘View Command Tool’.
These are the buttons of the command tool. Note that not all buttons may be inactive, depending on the current state and the capabilities of the inferior debugger.
RunInterruptStepStepiNextNextiUntilFinishContKillUpDownUndoRedoEditMakemake program with the most recently given arguments.
See Recompiling, for details.
The Command Tool can be customized in various ways.
See Customizing Buttons, for details on customizing the tool buttons.
You can disable the command tool and show its buttons in a separate row beneath the tool bar. To disable the command tool, set ‘Edit Preferences Source Tool Buttons Location Source Window’.
Here's the related resource:
Whether the tool buttons should be shown in a tool bar above the source window (‘on’) or within the command tool (‘off’, default). Enabling the command tool bar disables the command tool and vice versa.
The following resources control the position of the command tool (see Customizing):
If ‘on’ (default), DDD will always keep the command tool on top of other DDD windows. If this setting interferes with your window manager, or if your window manager keeps the command tool on top anyway, set this resource to ‘off’.
If ‘on’ (default), the command tool automatically follows every movement of the source window. Whenever the source window is moved, the command tool is moved by the same offset such that its position relative to the source window remains unchanged. If ‘off’, the command tool does not follow source window movements.
The distance between the right border of the command tool and the right border of the source text (in pixels). Default is 8.
The distance between the upper border of the command tool and the upper border of the source text (in pixels). Default is 8.
The following resources control the decoration of the command tool (see Customizing):
This resource controls the decoration of the command tool.
- If this is ‘off’, the command tool is created as a transient window. Several window managers keep transient windows automatically on top of their parents, which is appropriate for the command tool. However, your window manager may be configured not to decorate transient windows, which means that you cannot easily move the command tool around.
- If this is ‘on’, DDD realizes the command tool as a top-level window. Such windows are always decorated by the window manager. However, top-level windows are not automatically kept on top of other windows, such that you may wish to set the ‘autoRaiseTool’ resource, too.
- If this is ‘auto’ (default), DDD checks whether the window manager decorates transients. If yes, the command tool is realized as a transient window (as in the ‘off’ setting); if no, the command tool is realized as a top-level window (as in the ‘on’ setting). Hence, the command tool is always decorated using the “best” method, but the extra check takes some time.
DDD has an extensive on-line help system. Here's how to get help while working with DDD.
All these functions can be customized in various ways (see Customizing Help).
If, after all, you made a mistake, don't worry: almost every DDD command can be undone. See Undo and Redo, for details.
Almost every DDD command can be undone, using ‘Edit Undo’ or the ‘Undo’ button on the command tool.
Likewise, ‘Edit Redo’ repeats the command most recently undone.
The ‘Edit’ menu shows which commands are to be undone and redone next; this is also indicated by the popup help on the ‘Undo’ and ‘Redo’ buttons.
DDD is controlled by several resources—user-defined variables that take specific values in order to control and customize DDD behavior.
Most DDD resources can be set interactively while DDD is running or when invoking DDD. See Resource Index, for the full list of DDD resources.
We first discuss how customizing works in general; then we turn to customizing parts of DDD introduced so far.
Just like any X program, DDD has a number of places to get resource values from. For DDD, the most important places to specify resources are:
If the environment variable DDD_STATE is set, its value is used instead of ~/.ddd/.
Not every resource has a matching command-line option. Each resource (whether in ~/.ddd/init or Ddd) is specified using a line
Ddd*resource: value
For instance, to set the ‘pollChildStatus’ resource to ‘off’, you would specify in ~/.ddd/init:
Ddd*pollChildStatus: off
For more details on the syntax of resource specifications, see the section RESOURCES in the X(1) manual page.
You can change DDD resources by three methods:
You can save the current option settings by setting ‘Edit Save Options’. Options are saved in a file named .ddd/init in your home directory when DDD exits. If a session session is active, options will be saved in ~/.ddd/sessions/session/init instead.
The options are automatically saved when exiting DDD. You can turn off this feature by unsetting ‘Edit Save Options’. This is tied to the following resource:
If ‘on’ (default), the current option settings are automatically saved when DDD exits.
DDD Help can be customized in various ways.
Button tips are helpful for novices, but may be distracting for experienced users. You can turn off button tips via ‘Edit Preferences General Automatic display of Button Hints as Popup Tips’.
You can also turn off the hint that is displayed in the status line. Just toggle ‘Edit Preferences General Automatic Display of Button Hints in the Status Line’.
These are the related DDD resources (see Customizing):
You can turn off the tip of the day by toggling ‘Edit Preferences Startup Startup Windows Tip of the Day’.
Here is the related DDD resource (see Customizing):
If ‘on’ (default), show a tip of the day upon DDD startup.
See Options, for options to set this resource upon DDD invocation.
The actual tips are controlled by these resources (see Customizing):
The number n of the tip of the day to be shown at startup. See also the ‘tipn’ resources.
DDD relies on a number of external commands, specified via ‘Edit Preferences Helpers’.
To uncompress help texts, you can define a ‘Uncompress’ command:
The command to uncompress the built-in DDD manual, the DDD license, and the DDD news. Takes a compressed text from standard input and writes the uncompressed text to standard output. The default value is gzip -d -c; typical values include zcat and gunzip -c.
To view WWW pages, you can define a ‘Web Browser’ command:
The command to invoke a WWW browser. The string ‘@URL@’ is replaced by the URL to open. Default is to try a running Netscape first (trying mozilla, then netscape), then $WWWBROWSER, then to invoke a new Netscape process, then to let a running Emacs or XEmacs do the job (via gnudoit), then to invoke Firefox, then to invoke Lynx in an xterm.
To specify ‘netscape-6.0’ as browser, use the setting:
Ddd*wwwCommand: \ netscape-6.0 -remote 'openURL(@URL@)' \ || netscape-6.0 '@URL@'This command first tries to connect to a running
netscape-6.0browser; if this fails, it starts a newnetscape-6.0process.
This is the default WWW Page shown by ‘Help DDD WWW Page’:
DDD Undo can be customized in various ways.
To set a maximum size for the undo buffer, set ‘Edit Preferences General Undo Buffer Size’.
This is related to the ‘maxUndoSize’ resource:
The maximum memory usage (in bytes) of the undo buffer. Useful for limiting DDD memory usage. A negative value means to place no limit. Default is
2000000, or 2000 kBytes.
You can also limit the number of entries in the undo buffer, regardless of size (see Customizing):
The maximum number of entries in the undo buffer. This limits the number of actions that can be undone, and the number of states that can be shown in historic mode. Useful for limiting DDD memory usage. A negative value (default) means to place no limit.
To clear the undo buffer at any time, thus reducing memory usage, use ‘Edit Preferences General Clear Undo Buffer’
You can customize the DDD Windows in various ways.
You can turn off the DDD splash screen shown upon startup. Just select ‘Edit Preferences Startup DDD Splash Screen’.
The value applies only to the next DDD invocation.
This setting is related to the following resource:
If ‘on’ (default), show a DDD splash screen upon start-up.
You can also customize the appearance of the splash screen (see Customizing):
The color key to use for the DDD splash screen. Possible values include:
- ‘c’ (default) for a color visual,
- ‘g’ for a multi-level greyscale visual,
- ‘g4’ for a 4-level greyscale visual, and
- ‘m’ for a dithered monochrome visual.
- ‘best’ chooses the best visual available for your display.
Please note: if DDD runs on a monochrome display, or if DDD was compiled without the XPM library, only the monochrome version (‘m’) can be shown.
By default, DDD stacks commands, source, and data in one single top-level window. To have separate top-level windows for source, data, and debugger console, set ‘Edit Preferences Startup Window Layout Separate Windows’.
Here are the related DDD resources:
If ‘on’, the data window and the debugger console are realized in different top-level windows. If ‘off’ (default), the data window is attached to the debugger console.
If ‘on’, the source window and the debugger console are realized in different top-level windows. If ‘off’ (default), the source window is attached to the debugger console.
By default, the DDD tool bars are located on top of the window. If you prefer the tool bar being located at the bottom, as in DDD 2.x and earlier, set ‘Edit Preferences Startup Tool Bar Appearance Bottom’.
This is related to the ‘toolbarsAtBottom’ resource:
Whether source and data tool bars should be placed above source and data, respectively (‘off’, default), or below, as in DDD 2.x (‘on’).
The bottom setting is only supported for separate tool bars—that is, you must either choose separate windows or configure the tool bar to have neither images nor captions (see Customizing the Tool Bar).
If you use stacked windows, you can choose whether there should be one tool bar or two tool bars. By default, DDD uses two tool bars if you use separate windows and disable captions and images, but you can also explicitly change the setting via this resource:
Whether the tool bar buttons should be shown in one common tool bar at the top of the common DDD window (‘on’, default), or whether they should be placed in two separate tool bars, one for data, and one for source operations, as in DDD 2.x (‘off’).
You can also change the location of the status line (see Customizing):
If ‘on’ (default), the status line is placed at the bottom of the DDD source window. If ‘off’, the status line is placed at the top of the DDD source window (as in DDD 1.x).
See Options, for options to set these resources upon DDD invocation.
You can configure the basic DDD fonts at run-time. Each font is specified using two members:
To specify fonts, select ‘Edit Preferences Fonts’.
The ‘Browse’ button opens a font selection program, where you can select fonts and attributes interactively. Clicking ‘quit’ or ‘select’ in the font selector causes all non-default values to be transferred to the DDD font preferences panel.
The following fonts can be set using the preferences panel:
Default FontVariable WidthFixed WidthDataChanges in this panel will take effect only in the next DDD session. To make it effective right now, restart DDD (using ‘File Restart DDD’).
After having made changes in the panel, DDD will automatically offer you to restart itself, such that you can see the changes taking effect.
The ‘Reset’ button restores the most recently saved preferences.
Here are the resources related to font specifications:
The default DDD font to use for labels, menus, buttons, etc. The font is specified as an X font spec, where the initial Foundry specification may be omitted, as well as any specification after Family.
Default value is ‘helvetica-bold’.
To set the default DDD font to, say, ‘helvetica medium’, insert a line
Ddd*defaultFont: helvetica-mediumin your ~/.ddd/init file.
The size of the default DDD font, in 1/10 points. This resource overrides any font size specification in the ‘defaultFont’ resource (see above). The default value is
120for a 12.0 point font.
The variable width DDD font to use for help texts and messages. The font is specified as an X font spec, where the initial Foundry specification may be omitted, as well as any specification after Family.
Default value is ‘helvetica-medium-r’.
To set the variable width DDD font family to, say, ‘times’, insert a line
Ddd*fixedWidthFont: times-mediumin your ~/.ddd/init file.
The size of the variable width DDD font, in 1/10 points. This resource overrides any font size specification in the ‘variableWidthFont’ resource (see above). The default value is
120for a 12.0 point font.
The fixed width DDD font to use for source code, the debugger console, text fields, and the execution window. The font is specified as an X font spec, where the initial Foundry specification may be omitted, as well as any specification after Family.
Default value is ‘lucidatypewriter-medium’.
To set the fixed width DDD font family to, say, ‘courier’, insert a line
Ddd*fixedWidthFont: courier-mediumin your ~/.ddd/init file.
The size of the fixed width DDD font, in 1/10 points. This resource overrides any font size specification in the ‘fixedWidthFont’ resource (see above). The default value is
120for a 12.0 point font.
The fixed width DDD font to use data displays. The font is specified as an X font spec, where the initial Foundry specification may be omitted, as well as any specification after Family.
Default value is ‘lucidatypewriter-medium’.
To set the DDD data font family to, say, ‘courier’, insert a line
Ddd*dataFont: courier-mediumin your ~/.ddd/init file.
The size of the DDD data font, in 1/10 points. This resource overrides any font size specification in the ‘dataFont’ resource (see above). The default value is
120for a 12.0 point font.
As all font size resources have the same class (and by default the same value), you can easily change the default DDD font size to, say, 9.0 points by inserting a line
Ddd*FontSize: 90
in your ~/.ddd/init file.
Here's how to specify the command to select fonts:
A command to select from a list of fonts. The string ‘@FONT@’ is replaced by the current DDD default font; the string ‘@TYPE@’ is replaced by a symbolic name of the DDD font to edit. The program must either place the name of the selected font in the
PRIMARYselection or print the selected font on standard output. A typical value is:Ddd*fontSelectCommand: xfontsel -print
See Options, for options to set these resources upon DDD invocation.
In the default stacked window setting, you can turn the individual DDD windows on and off by toggling the respective items in the ‘View’ menu (see View Menu). When using separate windows (see Window Layout), you can close the individual windows via ‘File Close’ or by closing them via your window manager.
Whether windows are opened or closed when starting DDD is controlled by the following resources, immediately tied to the ‘View’ menu items:
If ‘off’ (default), the data window is closed upon start-up.
If ‘off’, the debugger console is closed upon start-up.
See Options, for options to set these resources upon DDD invocation.
The DDD text fields can be customized using the following resources:
The maximum number of items to display in pop-down value histories. A value of
0(default) means an unlimited number of values.
If ‘on’ (default), items in the pop-down value histories are sorted alphabetically. If ‘off’, most recently used values will appear at the top.
If you frequently switch between DDD and other multi-window applications, you may like to set ‘Edit Preferences General Iconify all windows at once’. This way, all DDD windows are iconified and deiconified as a group.
This is tied to the following resource:
If this is ‘on’, (un)iconifying any DDD window causes all other DDD windows to (un)iconify as well. Default is ‘off’, meaning that each DDD window can be iconified on its own.
If you want to keep DDD off your desktop during a longer computation, you may like to set ‘Edit Preferences General Uniconify when ready’. This way, you can iconify DDD while it is busy on a command (e.g. running a program); DDD will automatically pop up again after becoming ready (e.g. after the debugged program has stopped at a breakpoint). See Program Stop, for a discussion.
Here is the related resource:
If this is ‘on’ (default), the DDD windows are uniconified automatically whenever GDB becomes ready. This way, you can iconify DDD during some longer operation and have it uniconify itself as soon as the program stops. Setting this to ‘off’ leaves the DDD windows iconified.
You can extend DDD with new buttons. See Defining Buttons, for details.
You can change just about any label, color, keyboard mapping, etc. by changing resources from the Ddd application defaults file which comes with the DDD source distribution. Here's how it works:
See Application Defaults, for details on the application-defaults file.
For most inferior debuggers, you can change their internal settings using ‘Edit Settings’. Using the settings editor, you can determine whether C++ names are to be demangled, how many array elements are to print, and so on.
The capabilities of the settings editor depend on the capabilities of your inferior debugger. Clicking on ‘?’ gives an an explanation on the specific item; the GDB documentation gives more details.
Use ‘Edit Undo’ to undo changes. Clicking on ‘Reset’ restores the most recently saved settings.
Some debugger settings are insensitive and cannot be changed, because doing so would endanger DDD operation. See the ‘gdbInitCommands’ and ‘dbxInitCommands’ resources for details.
All debugger settings (except source and object paths) are saved with DDD options.
This chapter discusses how to access code from within DDD.
In order to debug a program effectively, you need to generate debugging information when you compile it. This debugging information is stored in the object file; it describes the data type of each variable or function and the correspondence between source line numbers and addresses in the executable code.9
To request debugging information, specify the -g option when you run the compiler.
Many C compilers are unable to handle the -g and -O options together. Using those compilers, you cannot generate optimized executables containing debugging information.
GCC, the GNU C compiler, supports -g with or without -O, making it possible to debug optimized code. We recommend that you always use -g whenever you compile a program. You may think your program is correct, but there is no sense in pushing your luck.
When you debug a program compiled with -g -O, remember that the optimizer is rearranging your code; the debugger shows you what is really there. Do not be too surprised when the execution path does not exactly match your source file! An extreme example: if you define a variable, but never use it, DDD never sees that variable—because the compiler optimizes it out of existence.
If you did not invoke DDD specifying a program to be debugged, you can use the ‘File’ menu to open programs, core dumps and sources.
To open a program to be debugged, select ‘File Open Program’.10 Click on ‘Open’ to open the program
In JDB, select ‘File Open Class’ instead. This gives you a list of available classes to choose from.
To re-open a recently debugged program or class, select ‘File Open Recent’ and choose a program or class from the list.
If no sources are found, See Source Path, for specifying source directories.
If a previous run of the program has crashed and you want to find out why, you can have DDD examine its core dump.11
To open a core dump for the program, select ‘File Open Core Dump’. Click on ‘Open’ to open the core dump.
Before ‘Open Core Dump’, you should first use ‘File Open Program’ to specify the program that generated the core dump and to load its symbol table.
To open a source file of the debugged program, select ‘File Open Source’.
Click on ‘Open’ to open the source file. See Source Path, if no sources are found.
When presenting files to be opened, DDD by default filters files when opening execution files, core dumps, or source files, such that the selection shows only suitable files. This requires that DDD opens each file, which may take time. See Customizing File Filtering, if you want to turn off this feature.
As soon as the source of the debugged program is available, the source window displays its current source text. (see Source Path, if a source text cannot be found.)
In the source window, you can lookup and examine function and variable definitions as well as search for arbitrary occurrences in the source text.
If you wish to lookup a specific function or variable definition whose name is visible in the source text, click with mouse button 1 on the function or variable name. The name is copied to the argument field. Change the name if desired and click on the ‘Lookup’ button to find its definition.
As a faster alternative, you can simply press mouse button 3 on the function name and select the ‘Lookup’ item from the source popup menu.
As an even faster alternative, you can also double-click on a function call (an identifier followed by a ‘(’ character) to lookup the function definition.
If a source file is not found, See Source Path, for specifying source directories.
If the item you wish to search is visible in the source text, click with mouse button 1 on it. The identifier is copied to the argument field. Click on the ‘Find >>’ button to find following occurrences and on ‘Find >> Find << ()’ to find previous occurrences.
By default, DDD finds only complete words. To search for arbitrary substrings, change the value of the ‘Source Find Words Only’ option.
After looking up a location, use ‘Edit Undo’ (or the ‘Undo’ button on the command tool) to go back to the original locations. ‘Edit Redo’ brings you back again to the location you looked for.
Executable programs sometimes do not record the directories of the source files from which they were compiled, just the names. Even when they do, the directories could be moved between the compilation and your debugging session.
Here's how GDB accesses source files; other inferior debuggers have similar methods.
GDB has a list of directories to search for source files; this is called the source path. Each time GDB wants a source file, it tries all the directories in the list, in the order they are present in the list, until it finds a file with the desired name. Note that the executable search path is not used for this purpose. Neither is the current working directory, unless it happens to be in the source path.
If GDB cannot find a source file in the source path, and the object program records a directory, GDB tries that directory too. If the source path is empty, and there is no record of the compilation directory, GDB looks in the current directory as a last resort.
To specify a source path for your inferior debugger, use ‘Edit Debugger Settings’ (see Debugger Settings and search for appropriate entries (in GDB, this is ‘Search path for source files’).
If ‘Debugger Settings’ has no suitable entry, you can also specify a source path for the inferior debugger when invoking DDD. See Inferior Debugger Options, for details.
When using JDB, you can set the CLASSPATH environment variable to specify directories where JDB (and DDD) should search for classes.
If DDD does not find a source file for any reason, check the following issues:
Using GDB, you can also create a local .gdbinit file that contains a line directory path. Here, path is a colon-separated list of source paths.
The source window can be customized in a number of ways, most of them accessed via ‘Edit Preferences Source’.
In the source text, the current execution position and breakpoints are indicated by symbols (glyphs). As an alternative, DDD can also indicate these positions using text characters. If you wish to disable glyphs, set ‘Edit Preferences Source Show Position and Breakpoints as Text Characters’ option. This also makes DDD run slightly faster, especially when scrolling.
This setting is tied to this resource:
If this is ‘on’, the current execution position and breakpoints are displayed as glyphs; otherwise, they are shown through characters in the text. The default is ‘on’. See Options, for the --glyphs and --no-glyphs options.
You can further control glyphs using the following resources:
Whether to cache (share) glyph images (‘on’) or not (‘off’). Caching glyph images requires less X resources, but has been reported to fail with OSF/Motif 2.1 on XFree86 servers. Default is ‘off’ for OSF/Motif 2.1 or later on GNU/Linux machines, and ‘on’ otherwise.
A delay (in ms) that says how much time to wait before updating glyphs while scrolling the source text. A small value results in glyphs being scrolled with the text, a large value disables glyphs while scrolling and makes scrolling faster. Default:
10.
The maximum number of glyphs to be displayed (default:
10). Raising this value causes more glyphs to be allocated, possibly wasting resources that are never needed.
Searching in the source text (see Textual Search) is controlled by these resources, changed via the ‘Source’ menu:
If this is ‘on’ (default), the ‘Find’ commands are case-sensitive. Otherwise, occurrences are found regardless of case.
If this is ‘on’ (default), the ‘Find’ commands find complete words only. Otherwise, arbitrary occurrences are found.
You can have DDD show line numbers within the source window. Use ‘Edit Preferences Source Display Source Line Numbers’.
If this is ‘on’, lines in the source text are prefixed with their respective line number. The default is ‘off’.
You can instruct DDD to indent the source code, leaving more
room for breakpoints and execution glyphs. This is done using the
‘Edit Preferences Source Source
indentation’ slider. The default value is 0 for no indentation
at all.
The number of columns to indent the source code, such that there is enough place to display breakpoint locations. Default:
0.
By default, DDD uses a minimum indentation for script languages.
The minimum indentation for script languages, such as Perl, Python, and Bash. Default:
4.
The maximum width of line numbers is controlled by this resource.
The number of columns to use for line numbers (if displaying line numbers is enabled). Line numbers wider than this value extend into the breakpoint space. Default:
4.
If your source code uses a tab width different from 8 (the
default), you can set an alternate width using the ‘Edit
Preferences Source Tab width’ slider.
These resources control when the source window is scrolled:
The minimum number of lines to show before the current location. Default is
2.
The minimum number of lines to show after the current location. Default is
3.
Some DBX and XDB variants do not properly handle paths in source file specifications. If you want the inferior debugger to refer to source locations by source base names only, unset the ‘Edit Preferences Source Refer to Program Sources by full path name’ option.
This is related to the following resource:
If this is ‘off’ (default), the inferior debugger refers to source code locations only by their base names. If this is ‘on’ (default), DDD uses the full source code paths.
By default, DDD caches source files in memory. This is convenient for remote debugging, since remote file access may be slow. If you want to reduce memory usage, unset the ‘Edit Preferences Source Cache source files’ option.
This is related to the following resource:
Whether to cache source files (‘on’, default) or not (‘off’). Caching source files requires more memory, but makes DDD run faster.
You can control whether DDD should filter files to be opened.
If this is ‘on’ (default), DDD filters files when opening execution files, core dumps, or source files, such that the selection shows only suitable files. This requires that DDD opens each file, which may take time. If this is ‘off’, DDD always presents all available files.
The principal purposes of using a debugger are so that you can stop your program before it terminates; or so that, if your program runs into trouble, you can investigate and find out why.
Inside DDD, your program may stop for any of several reasons, such as a signal, a breakpoint, or reaching a new line after a DDD command such as ‘Step’. You may then examine and change variables, set new breakpoints or remove old ones, and then continue execution.
The inferior debuggers supported by DDD support two mechanisms for stopping a program upon specific events:
You can set breakpoints by location or by name.
Breakpoints are set at a specific location in the program.
If the source line is visible, click with mouse button 1 on the left of the source line and then on the ‘Break’ button.
As a faster alternative, you can simply press mouse button 3 on the left of the source line and select the ‘Set Breakpoint’ item from the line popup menu.
As an even faster alternative, you can simply double-click on the left of the source line to set a breakpoint.
As yet another alternative, you can select ‘Source Breakpoints’. Click on the ‘Break’ button and enter the location.
(If you find this number of alternatives confusing, be aware that DDD users fall into three categories, which must all be supported. Novice users explore DDD and may prefer to use one single mouse button. Advanced users know how to use shortcuts and prefer popup menus. Experienced users prefer the command line interface.)
Breakpoints are indicated by a plain stop sign, or as ‘#n’, where n is the breakpoint number. A greyed out stop sign (or ‘_n_’) indicates a disabled breakpoint. A stop sign with a question mark (or ‘?n?’) indicates a conditional breakpoint or a breakpoint with an ignore count set.
If you set a breakpoint by mistake, use ‘Edit Undo’ to delete it again.
If the function name is visible, click with mouse button 1 on the function name. The function name is then copied to the argument field. Click on the ‘Break’ button to set a breakpoint there.
As a shorter alternative, you can simply press mouse button 3 on the function name and select the ‘Break at’ item from the popup menu.
As yet another alternative, you can click on ‘Break...’ from the Breakpoint editor (invoked through ‘Source Breakpoints’) and enter the function name.
Using GDB, you can also set a breakpoint on all functions that match a given string. ‘Break Set Breakpoints at Regexp ()’ sets a breakpoint on all functions whose name matches the regular expression given in ‘()’. Here are some examples:
To delete a visible breakpoint, click with mouse button 1 on the breakpoint. The breakpoint location is copied to the argument field. Click on the ‘Clear’ button to delete all breakpoints there.
If the function name is visible, click with mouse button 1 on the function name. The function name is copied to the argument field. Click on the ‘Clear’ button to clear all breakpoints there.
As a faster alternative, you can simply press mouse button 3 on the breakpoint and select the ‘Delete Breakpoint’ item from the popup menu.
As yet another alternative, you can select the breakpoint and click on ‘Delete’ in the Breakpoint editor (invoked through ‘Source Breakpoints’).
As an even faster alternative, you can simply double-click on the breakpoint while holding <Ctrl>.
Rather than deleting a breakpoint or watchpoint, you might prefer to disable it. This makes the breakpoint inoperative as if it had been deleted, but remembers the information on the breakpoint so that you can enable it again later.12
To disable a breakpoint, press mouse button 3 on the breakpoint symbol and select the ‘Disable Breakpoint’ item from the breakpoint popup menu. To enable it again, select ‘Enable Breakpoint’.
As an alternative, you can select the breakpoint and click on ‘Disable’ or ‘Enable’ in the Breakpoint editor (invoked through ‘Source Breakpoints’.
Disabled breakpoints are indicated by a grey stop sign, or ‘_n_’, where n is the breakpoint number.
The ‘Disable Breakpoint’ item is also accessible via the ‘Clear’ button. Just press and hold mouse button 1 on the button to get a popup menu.
A temporary breakpoint is immediately deleted as soon as it is reached.13
To set a temporary breakpoint, press mouse button 3 on the left of the source line and select the ‘Set Temporary Breakpoint’ item from the popup menu.
As a faster alternative, you can simply double-click on the left of the source line while holding <Ctrl>.
Temporary breakpoints are convenient to make the program continue up to a specific location: just set the temporary breakpoint at this location and continue execution.
The ‘Continue Until Here’ item from the popup menu sets a temporary breakpoint on the left of the source line and immediately continues execution. Execution stops when the temporary breakpoint is reached.
The ‘Set Temporary Breakpoint’ and ‘Continue Until Here’ items are also accessible via the ‘Break’ button. Just press and hold mouse button 1 on the button to get a popup menu.
You can change all properties of a breakpoint by pressing mouse button 3 on the breakpoint symbol and select ‘Properties’ from the breakpoint popup menu. This will pop up a dialog showing the current properties of the selected breakpoint.
As an even faster alternative, you can simply double-click on the breakpoint.
The simplest sort of breakpoint breaks every time your program reaches a specified place. You can also specify a condition for a breakpoint. A condition is just a Boolean expression in your programming language. A breakpoint with a condition evaluates the expression each time your program reaches it, and your program stops only if the condition is true.
This is the converse of using assertions for program validation; in that situation, you want to stop when the assertion is violated–that is, when the condition is false. In C, if you want to test an assertion expressed by the condition assertion, you should set the condition ‘!assertion’ on the appropriate breakpoint.
Break conditions can have side effects, and may even call functions in your program. This can be useful, for example, to activate functions that log program progress, or to use your own print functions to format special data structures. The effects are completely predictable unless there is another enabled breakpoint at the same address. (In that case, DDD might see the other breakpoint first and stop your program without checking the condition of this one.)
Note that breakpoint commands are usually more convenient and flexible for the purpose of performing side effects when a breakpoint is reached. See Breakpoint Commands, for details.
A special case of a breakpoint condition is to stop only when the breakpoint has been reached a certain number of times. This is so useful that there is a special way to do it, using the ignore count of the breakpoint. Every breakpoint has an ignore count, which is an integer. Most of the time, the ignore count is zero, and therefore has no effect. But if your program reaches a breakpoint whose ignore count is positive, then instead of stopping, it just decrements the ignore count by one and continues. As a result, if the ignore count value is n, the breakpoint does not stop the next n times your program reaches it.
In the field ‘Ignore Count’ of the ‘Breakpoint Properties’ panel, you can specify the breakpoint ignore count.15
If a breakpoint has a positive ignore count and a condition, the condition is not checked. Once the ignore count reaches zero, DDD resumes checking the condition.
You can give any breakpoint (or watchpoint) a series of DDD commands to execute when your program stops due to that breakpoint. For example, you might want to print the values of certain expressions, or enable other breakpoints.16
Using the ‘Commands’ buttons of the ‘Breakpoint Properties’ panel, you can edit commands to be executed when the breakpoint is hit.
To edit breakpoint commands, click on ‘Edit >>’ and enter the commands in the commands editor. When done with editing, click on ‘Edit <<’ to close the commands editor.
Using GDB, you can also record a command sequence to be executed. To record a command sequence, follow these steps:
To move a breakpoint to a different location, press mouse button 1 on the stop sign and drag it to the desired location.17 This is equivalent to deleting the breakpoint at the old location and setting a breakpoint at the new location. The new breakpoint inherits all properties of the old breakpoint, except the breakpoint number.
To copy a breakpoint to a new location, press <Shift> while dragging.
If you wish to lookup a specific breakpoint, select ‘Source Breakpoints Lookup’. After selecting a breakpoint from the list and clicking the ‘Lookup’ button, the breakpoint location is displayed.
As an alternative, you can enter ‘#n’ in the argument field, where n is the breakpoint number, and click on the ‘Lookup’ button to find its definition.
To view and edit all breakpoints at once, select ‘Source Breakpoints’. This will popup the Breakpoint Editor which displays the state of all breakpoints.
In the breakpoint editor, you can select individual breakpoints by clicking on them. Pressing <Ctrl> while clicking toggles the selection. To edit the properties of all selected breakpoints, click on ‘Props’.
Using GDB, a few more commands related to breakpoints can be invoked through the debugger console:
See Setting breakpoints, for details.
You can make the program stop as soon as some variable value changes, or when some variable is read or written. This is called setting a watchpoint on a variable.18
Watchpoints have much in common with breakpoints: in particular, you can enable and disable them. You can also set conditions, ignore counts, and commands to be executed when a watched variable changes its value.
Please note: on architectures without special watchpoint support, watchpoints currently make the program execute two orders of magnitude more slowly. This is so because the inferior debugger must interrupt the program after each machine instruction in order to examine whether the watched value has changed. However, this delay can be well worth it to catch errors when you have no clue what part of your program is the culprit.
If the variable name is visible, click with mouse button 1 on the variable name. The variable name is copied to the argument field. Otherwise, enter the variable name in the argument field. Click on the ‘Watch’ button to set a watchpoint there.
Using GDB and JDB 1.2, you can set different types of watchpoints. Click and hold mouse button 1 on the ‘Watch’ button to get a menu.
To change the properties of a watchpoint, enter the name of the watched variable in the argument field. Click and hold mouse button 1 on the ‘Watch’ button and select ‘Watchpoint Properties’.
The Watchpoint Properties panel has the same functionality as the Breakpoint Properties panel (see Editing Breakpoint Properties). As an additional feature, you can click on ‘Print’ to see the current value of a watched variable.
To view and edit all watchpoints at once, select ‘Data Watchpoints’. This will popup the Watchpoint Editor which displays the state of all watchpoints.
The Watchpoint Editor has the same functionality as the Breakpoint Editor (see Editing all Breakpoints). As an additional feature, you can click on ‘Print’ to see the current value of a watched variable.
To delete a watchpoint, enter the name of the watched variable in the argument field and click the ‘Unwatch’ button.
If the program is already running (see Running), you can interrupt
it any time by clicking the ‘Interrupt’ button or typing <ESC>
in a DDD window.19 Using GDB, this is
equivalent to sending a SIGINT (Interrupt) signal.
‘Interrupt’ and <ESC> also interrupt a running debugger command, such as printing data.
If your program is a modal X application, DDD may interrupt it while it has grabbed the mouse pointer, making further interaction impossible—your X display will be unresponsive to any user actions.
By default, DDD will check after each interaction whether the pointer is grabbed. If the pointer is grabbed, DDD will continue the debugged program such that you can continue to use your X display.
This is how this feature works: When the program stops, DDD checks for input events such as keyboard or mouse interaction. If DDD does not receive any event within the next 5 seconds, DDD checks whether the mouse pointer is grabbed by attempting to grab and ungrab it. If this attempt fails, then DDD considers the pointer grabbed.
Unfortunately, DDD cannot determine the program that grabbed the pointer—it may be the debugged program, or another program. Consequently, you have another 10 seconds to cancel continuation before DDD continues the program automatically.
There is one situation where this fails: if you lock your X display while DDD is running, then DDD will consider a resulting pointer grab as a result of running the program—and automatically continue execution of the debugged program. Consequently, you can turn off this feature via ‘Edit Preferences General Continue Automatically when Mouse Pointer is Frozen’.
The grab checks are controlled by the following resources:
If this is ‘on’ (default), DDD will check after each interaction whether the pointer is grabbed. If this is so, DDD will automatically continue execution of debugged program.
The time to wait (in ms) after a debugger command before checking for a grabbed pointer. If DDD sees some pointer event within this delay, the pointer cannot be grabbed and an explicit check for a grabbed pointer is unnecessary. Default is
5000, or 5 seconds.
The action to take after having detected a grabbed mouse pointer. This is a list of newline-separated commands. Default is cont, meaning to continue the debuggee. Other possible choices include kill (killing the debuggee) or quit (exiting DDD).
The time to wait (in ms) before taking an action due to having detected a grabbed pointer. During this delay, a working dialog pops up telling the user about imminent execution of the grab action (see the ‘grabAction’ resource, above). If the pointer grab is released within this delay, the working dialog pops down and no action is taken. This is done to exclude pointer grabs from sources other than the debugged program (including DDD). Default is
10000, or 10 seconds.
You may start the debugged program with its arguments, if any, in an environment of your choice. You may redirect your program's input and output, debug an already running process, or kill a child process.
To start execution of the debugged program, select ‘Program Run’. You will then be prompted for the arguments to pass to your program. You can either select from a list of previously used arguments or enter own arguments in the text field. Afterwards, press the ‘Run’ button to start execution with the selected arguments.
To run your program again, with the same arguments, select ‘Program Run Again’ or press the ‘Run’ button on the command tool. You may also enter run, followed by arguments at the debugger prompt instead.
When you click on ‘Run’, your program begins to execute immediately. See Stopping, for a discussion of how to arrange for your program to stop. Once your program has stopped, you may call functions in your program to examine data. See Examining Data, for details.
If the modification time of your symbol file has changed since the last time GDB read its symbols, GDB discards its symbol table, and reads it again. When it does this, GDB and DDD try to retain your current debugger state, such as breakpoints.
The arguments to your program are specified by the arguments of the ‘run’ command, as composed in ‘Program Run’.
In GDB, the arguments are passed to a shell, which expands wildcard characters and performs redirection of I/O, and thence to your program. Your SHELL environment variable (if it exists) specifies what shell GDB uses. If you do not define SHELL, GDB uses ‘/bin/sh’.
If you use another inferior debugger, the exact semantics on how the arguments are interpreted depend on the inferior debugger you are using. Normally, the shell is used to pass the arguments, so that you may use normal conventions (such as wildcard expansion or variable substitution) in describing the arguments.
Your program normally inherits its environment from the inferior debugger, which again inherits it from DDD, which again inherits it from its parent process (typically the shell or desktop).
In GDB, you can use the commands set environment and unset environment to change parts of the environment that affect your program. See Your program's environment, for details.
The following environment variables are set by DDD:
The inferior debugger, in turn, might also set or unset some environment variables.
Your program normally inherits its working directory from the inferior debugger, which again inherits it from DDD, which again inherits it from its parent process (typically the shell or desktop).
You can change the working directory of the inferior debugger via ‘File Change Directory’ or via the ‘cd’ command of the inferior debugger.
By default, the program you run under DDD does input and output to the debugger console. Normally, you can redirect your program's input and/or output using shell redirections with the arguments—that is, additional arguments like ‘< input’ or ‘> output’. You can enter these shell redirections just like other arguments (see Arguments).
Warning: While input and output redirection work, you cannot use pipes to pass the output of the program you are debugging to another program; if you attempt this, DDD may wind up debugging the wrong program. See Attaching to a Process, for an alternative.
If command output is sent to the debugger console, it is impossible for DDD to distinguish between the output of the debugged program and the output of the inferior debugger.
Program output that confuses DDD includes:
If your program outputs any of these strings, you may encounter problems with DDD mistaking them for debugger output. These problems can easily be avoided by redirecting program I/O, for instance to the separate execution window (see Using the Execution Window).
If the inferior debugger changes the default TTY settings, for instance through a stty command in its initialization file, DDD may also become confused. The same applies to debugged programs which change the default TTY settings.
The behavior of the debugger console can be controlled using the following resource:
If this is ‘on’ (default), each line from the inferior debugger is output on each own, such that the final line is placed at the bottom of the debugger console. If this is ‘off’, all lines are output as a whole. This is faster, but results in a random position of the last line.
By default, input and output of your program go to the debugger console. As an alternative, DDD can also invoke an execution window, where the program terminal input and output is shown.21
To activate the execution window, select ‘Program Run in Execution Window’.
Using the execution window has an important side effect: The output of your program no longer gets intermixed with the output of the inferior debugger. This makes it far easier for DDD to parse the debugger output correctly. See Debugger Communication, for details on the ‘bufferGDBOutput’ resource.
The execution window is opened automatically as soon as you start the debugged program. While the execution window is active, DDD redirects the standard input, output, and error streams of your program to the execution window. Note that the device ‘/dev/tty’ still refers to the debugger console, not the execution window.
You can override the DDD stream redirection by giving alternate redirection operations as arguments. For instance, to have your program read from file, but to write to the execution window, invoke your program with ‘< file’ as argument. Likewise, to redirect the standard error output to the debugger console, use ‘2> /dev/tty’ (assuming the inferior debugger and/or your UNIX shell support standard error redirection).
You can customize the DDD execution window and use a different TTY command. The command is set by ‘Edit Preferences Helpers Execution Window’:
The command to invoke for the execution window—a TTY emulator that shows the input/output of the debugged program. A Bourne shell command to run in the separate TTY is appended to this string. The string ‘@FONT@’ is replaced by the name of the fixed width font used by DDD. A simple value is
Ddd*termCommand: xterm -fn @FONT@ -e /bin/sh -c
You can also set the terminal type:
The terminal type provided by the ‘termCommand’ resource—that is, the value of the TERM environment variable to be passed to the debugged program. Default: ‘xterm’.
Whether the execution window is active or not, as set by ‘Program Run in Execution Window’, is saved using this resource:
If ‘on’, the debugged program is executed in a separate execution window. If ‘off’ (default), the debugged program is executed in the console window.
If the debugged program is already running in some process, you can attach to this process (instead of starting a new one with ‘Run’).22
To attach DDD to a process, select ‘File Attach to Process’. You can now choose from a list of processes. Then, press the ‘Attach’ button to attach to the specified process.
The first thing DDD does after arranging to debug the specified process is to stop it. You can examine and modify an attached process with all the DDD commands that are ordinarily available when you start processes with ‘Run’. You can insert breakpoints; you can step and continue; you can modify storage. If you would rather the process continue running, you may use ‘Continue’ after attaching DDD to the process.
When using ‘Attach to Process’, you should first use ‘Open Program’ to specify the program running in the process and load its symbol table.
When you have finished debugging the attached process, you can use the ‘File Detach Process’ to release it from DDD control. Detaching the process continues its execution. After ‘Detach Process’, that process and DDD become completely independent once more, and you are ready to attach another process or start one with ‘Run’.
You can customize the list of processes shown by defining an alternate command to list processes. See ‘Edit Preferences Helpers List Processes’; See Customizing Attaching to Processes, for details.
When attaching to a process (see Attaching to a Process), DDD uses a ps command to get the list of processes. This command is defined by the ‘psCommand’ resource.
The command to get a list of processes. Usually ps. Depending on your system, useful alternate values include ps -ef and ps ux. The first line of the output must either contain a ‘PID’ title, or each line must begin with a process ID.
Note that the output of this command is filtered by DDD; a process is only shown if it can be attached to. The DDD process itself as well as the process of the inferior debugger are suppressed, too.
After the program has been started, it runs until one of the following happens:
DDD shows the current program status in the debugger console. The current execution position is highlighted by an arrow.
If ‘Edit Preferences General Uniconify When Ready’ is set, DDD automatically deiconifies itself when the program stops. This way, you can iconify DDD during a lengthy computation and have it uniconify as soon as the program stops.
To resume execution, at the current execution position, click on the ‘Continue’ button. Any breakpoints set at the current execution position are bypassed.
To execute just one source line, click on the ‘Step’ button. The program is executed until control reaches a different source line, which may be in a different function. Then, the program is stopped and control returns to DDD.
Warning: If you use the ‘Step’ button while control is within a function that was compiled without debugging information, execution proceeds until control reaches a function that does have debugging information. Likewise, it will not step into a function which is compiled without debugging information. To step through functions without debugging information, use the ‘Stepi’ button (see Machine Code Execution).
In GDB, the ‘Step’ button only stops at the first instruction of a source line. This prevents the multiple stops that used to occur in switch statements, for loops, etc. ‘Step’ continues to stop if a function that has debugging information is called within the line.
Also, the ‘Step’ in GDB only enters a subroutine if there is line number information for the subroutine. Otherwise it acts like the ‘Next’ button.
To continue to the next line in the current function, click on the ‘Next’ button. This is similar to ‘Step’, but any function calls appearing within the line of code are executed without stopping.
Execution stops when control reaches a different line of code at the original stack level that was executing when you clicked on ‘Next’.
To continue running until a specific location is reached, use the ‘Continue Until Here’ facility from the line popup menu. See Temporary Breakpoints, for a discussion.
To continue until a greater line in the current function is reached, click on the ‘Until’ button. This is useful to avoid single stepping through a loop more than once.
‘Until’ is like ‘Next’, except that when ‘Until’ encounters a jump, it automatically continues execution until the program counter is greater than the address of the jump.
This means that when you reach the end of a loop after single stepping though it, ‘until’ makes your program continue execution until it exits the loop. In contrast, clicking on ‘Next’ at the end of a loop simply steps back to the beginning of the loop, which forces you to step through the next iteration.
‘Until’ always stops your program if it attempts to exit the current stack frame.
‘Until’ works by means of single instruction stepping, and hence is slower than continuing until a breakpoint is reached.
To continue running until the current function returns, use the ‘Finish’ button. The returned value (if any) is printed.
Ordinarily, when you continue your program, you do so at the place where it stopped. You can instead continue at an address of your own choosing.
The most common occasion to use this feature is to back up—perhaps with more breakpoints set-over a portion of a program that has already executed, in order to examine its execution in more detail.
To set the execution position to the current location, use ‘Set Execution Position’ from the breakpoint popup menu. This item is also accessible by pressing and holding the ‘Break/Clear’ button.23
As a quicker alternative, you can also press mouse button 1 on the arrow and drag it to a different location.24
Moving the execution position does not change the current stack frame, or the stack pointer, or the contents of any memory location or any register other than the program counter.
Some inferior debuggers (notably GDB) allow you to set the new execution position into a different function from the one currently executing. This may lead to bizarre results if the two functions expect different patterns of arguments or of local variables. For this reason, moving the execution position requests confirmation if the specified line is not in the function currently executing.
After moving the execution position, click on ‘Continue’ to resume execution.
When your program has stopped, the first thing you need to know is where it stopped and how it got there.
Each time your program performs a function call, information about the call is generated. That information includes the location of the call in your program, the arguments of the call, and the local variables of the function being called. The information is saved in a block of data called a stack frame. The stack frames are allocated in a region of memory called the call stack.
When your program stops, the DDD commands for examining the stack allow you to see all of this information.
One of the stack frames is selected by DDD and many DDD commands refer implicitly to the selected frame. In particular, whenever you ask DDD for the value of a variable in your program, the value is found in the selected frame. There are special DDD commands to select whichever frame you are interested in.
The call stack is divided up into contiguous pieces called stack frames, or frames for short; each frame is the data associated with one call to one function. The frame contains the arguments given to the function, the function's local variables, and the address at which the function is executing.
When your program is started, the stack has only one frame, that of the
function main. This is called the initial frame or the
outermost frame. Each time a function is called, a new frame is
made. Each time a function returns, the frame for that function invocation
is eliminated. If a function is recursive, there can be many frames for
the same function. The frame for the function in which execution is
actually occurring is called the innermost frame. This is the most
recently created of all the stack frames that still exist.
Inside your program, stack frames are identified by their addresses. A stack frame consists of many bytes, each of which has its own address; each kind of computer has a convention for choosing one byte whose address serves as the address of the frame. Usually this address is kept in a register called the frame pointer register while execution is going on in that frame.
GDB assigns numbers to all existing stack frames, starting with zero for the innermost frame, one for the frame that called it, and so on upward. These numbers do not really exist in your program; they are assigned by GDB to give you a way of designating stack frames in GDB commands.
DDD provides a backtrace window showing a summary of how your program got where it is. It shows one line per frame, for many frames, starting with the currently executing frame (frame zero), followed by its caller (frame one), and on up the stack.
To enable the backtrace window, select ‘Status Backtrace’.
Using GDB, each line in the backtrace shows the frame number and the function name. The program counter value is also shown—unless you use the GDB command ‘set print address off’. The backtrace also shows the source file name and line number, as well as the arguments to the function. The program counter value is omitted if it is at the beginning of the code for that line number.
Most commands for examining the stack and other data in your program work on whichever stack frame is selected at the moment. Here are the commands for selecting a stack frame.25
In the backtrace window, you can select an arbitrary frame to move from one stack frame to another. Just click on the desired frame.
The ‘Up’ button selects the function that called the current one—that is, it moves one frame up.
The ‘Down’ button selects the function that was called by the current one—that is, it moves one frame down.
You can also directly type the up and down commands at the debugger prompt. Typing <Ctrl+Up> and <Ctrl+Down>, respectively, will also move you through the stack.
‘Up’ and ‘Down’ actions can be undone via ‘Edit Undo’.
If you take a look at the ‘Edit Undo’ menu item after an execution command, you'll find that DDD offers you to undo execution commands just as other commands. Does this mean that DDD allows you to go backwards in time, undoing program execution as well as undoing any side-effects of your program?
Sorry—we must disappoint you. DDD cannot undo what your program did. (After a little bit of thought, you'll find that this would be impossible in general.) However, DDD can do something different: it can show previously recorded states of your program.
After “undoing” an execution command (via ‘Edit Undo’, or the ‘Undo’ button), the execution position moves back to the earlier position and displayed variables take their earlier values. Your program state is in fact unchanged, but DDD gives you a view on the earlier state as recorded by DDD.
In this so-called historic mode, most normal DDD commands that would query further information from the program are disabled, since the debugger cannot be queried for the earlier state. However, you can examine the current execution position, or the displayed variables. Using ‘Undo’ and ‘Redo’, you can move back and forward in time to examine how your program got into the present state.
To let you know that you are operating in historic mode, the execution arrow gets a dashed-line appearance (indicating a past position); variable displays also come with dashed lines. Furthermore, the status line informs you that you are seeing an earlier program state.
Here's how historic mode works: each time your program stops, DDD collects the current execution position and the values of displayed variables. Backtrace, thread, and register information is also collected if the corresponding dialogs are open. When “undoing” an execution command, DDD updates its view from this collected state instead of querying the program.
If you want to collect this information without interrupting your program—within a loop, for instance—you can place a breakpoint with an associated cont command (see Breakpoint Commands). When the breakpoint is hit, DDD will stop, collect the data, and execute the ‘cont’ command, resuming execution. Using a later ‘Undo’, you can step back and look at every single loop iteration.
To leave historic mode, you can use ‘Redo’ until you are back in the current program state. However, any DDD command that refers to program state will also leave historic mode immediately by applying to the current program state instead. For instance, ‘Up’ leaves historic mode immediately and selects an alternate frame in the restored current program state.
If you want to see the history of a specific variable, as recorded during program stops, you can enter the DDD command
graph history name
This returns a list of all previously recorded values of the variable name, using array syntax. Note that name must have been displayed at earlier program stops in order to record values.
In some operating systems, a single program may have more than one thread of execution. The precise semantics of threads differ from one operating system to another, but in general the threads of a single program are akin to multiple processes—except that they share one address space (that is, they can all examine and modify the same variables). On the other hand, each thread has its own registers and execution stack, and perhaps private memory.
For debugging purposes, DDD lets you display the list of threads currently active in your program and lets you select the current thread—the thread which is the focus of debugging. DDD shows all program information from the perspective of the current thread.26
To view all currently active threads in your program, select ‘Status Threads’. The current thread is highlighted. Select any thread to make it the current thread.
Using JDB, additional functionality is available:
For more information on threads, see the JDB and GDB documentation (see Debugging programs with multiple threads).
A signal is an asynchronous event that can happen in a program. The
operating system defines the possible kinds of signals, and gives each
kind a name and a number. For example, in UNIX, SIGINT is the
signal a program gets when you type an interrupt; SIGSEGV is
the signal a program gets from referencing a place in memory far away
from all the areas in use; SIGALRM occurs when the alarm clock
timer goes off (which happens only if your program has requested an
alarm).
Some signals, including SIGALRM, are a normal part of the
functioning of your program. Others, such as SIGSEGV, indicate
errors; these signals are fatal (kill your program immediately)
if the program has not specified in advance some other way to handle the
signal. SIGINT does not indicate an error in your program, but
it is normally fatal so it can carry out the purpose of the interrupt:
to kill the program.
GDB has the ability to detect any occurrence of a signal in your program. You can tell GDB in advance what to do for each kind of signal.
Normally, DDD is set up to ignore non-erroneous signals like
SIGALRM (so as not to interfere with their role in the
functioning of your program) but to stop your program immediately
whenever an error signal happens. In DDD, you can view and edit
these settings via ‘Status Signals’.
‘Status Signals’ pops up a panel showing all the kinds of signals and how GDB has been told to handle each one. The settings available for each signal are:
StopPrintIf unset, GDB should not mention the occurrence of the signal at all.
This also implies ‘Stop’ being unset.
PassIf unset, GDB should not allow your program to see this signal.
The entry ‘All Signals’ is special. Changing a setting here affects all signals at once—except those used by the debugger, typically
SIGTRAP and SIGINT.
To undo any changes, use ‘Edit Undo’. The ‘Reset’ button restores the saved settings.
When a signal stops your program, the signal is not visible until you continue. Your program sees the signal then, if ‘Pass’ is in effect for the signal in question at that time. In other words, after GDB reports a signal, you can change the ‘Pass’ setting in ‘Status Signals’ to control whether your program sees that signal when you continue.
You can also cause your program to see a signal it normally would not see, or to give it any signal at any time. The ‘Send’ button will resume execution where your program stopped, but immediately give it the signal shown.
On the other hand, you can also prevent your program from seeing a signal. For example, if your program stopped due to some sort of memory reference error, you might store correct values into the erroneous variables and continue, hoping to see more execution; but your program would probably terminate immediately as a result of the fatal signal once it saw the signal. To prevent this, you can resume execution using ‘Commands Continue Without Signal’.
Signal settings are not saved across DDD invocations, since changed signal settings are normally useful within specific projects only. Instead, signal settings are saved with the current session, using ‘File Save Session As’.
You can kill the process of the debugged program at any time using the ‘Kill’ button. Killing the process is useful if you wish to debug a core dump instead of a running process. GDB ignores any core dump file while your program is running.
The ‘Kill’ button is also useful if you wish to recompile and relink your program, since on many systems it is impossible to modify an executable file while it is running in a process. In this case, when you next click on ‘Run’, GDB notices that the file has changed, and reads the symbol table again (while trying to preserve your current debugger state).
DDD provides several means to examine data.
To display the value of a simple variable, move the mouse pointer on its name. After a second, a small window (called value tip) pops up showing the value of the variable pointed at. The window disappears as soon as you move the mouse pointer away from the variable. The value is also shown in the status line.
You can disable value tips via ‘Edit Preferences General Automatic display of variable values as popup tips’.
You can disable displaying variable values in the status line via ‘Edit Preferences General Automatic display of variable values in the status line’.
These customizations are tied to the following resources:
Whether value tips are enabled (‘on’, default) or not (‘off’). Value tips affect DDD performance and may be distracting for some experienced users.
Whether the display of variable values in the status line is enabled (‘on’, default) or not (‘off’).
You can turn off value tips via ‘Edit Preferences General Automatic Display of Variable Values’.
The variable value can also be printed in the debugger console, making it available for future operations. To print a variable value, select the desired variable by clicking mouse button 1 on its name. The variable name is copied to the argument field. By clicking the ‘Print’ button, the value is printed in the debugger console. The printed value is also shown in the status line.
As a shorter alternative, you can simply press mouse button 3 on the variable name and select the ‘Print’ item from the popup menu.
In GDB, the ‘Print’ button generates a print command, which has several more options. See Examining Data, for GDB-specific expressions, variables, and output formats.
To explore complex data structures, you can display them permanently in the data window. The data window displays selected data of your program, showing complex data structures graphically. It is updated each time the program stops.
This section discusses how to create, manipulate, and delete displays. The essentials are:
To create a new display showing a specific variable, select the variable by clicking mouse button 1 on its name. The variable name is copied to the argument field. By clicking the ‘Display’ button, a new display is created in the data window. The data window opens automatically as soon as you create a display.
As a shorter alternative, you can simply press mouse button 3 on the variable name and select ‘Display’ from the popup menu.
As an even faster alternative, you can also double-click on the variable name.
As another alternative, you may also enter the expression to be displayed in the argument field and press the ‘Display’ button.
Finally, you may also type in a command at the debugger prompt:
graph display expr [clustered] [at (x, y)]
[dependent on display] [[now or] when in scope]
This command creates a new display showing the value of the expression expr. The optional parts have the following meaning:
clusteredat (x, y)dependent on displaywhen in scopenow or when in scopeIf ‘now or when in’ is given, DDD first attempts to create the display immediately. The display is deferred only if display creation fails.
If neither ‘when in’ suffix nor ‘now or when in’ suffix is given, the display is created immediately.
Each display in the data window has a title bar containing the display number and the displayed expression (the display name). Below the title, the display value is shown.
You can select single displays by clicking on them with mouse button 1.
You can extend an existing selection by pressing the <Shift> key while selecting. You can also toggle an existing selection by pressing the <Shift> key while selecting already selected displays.
Single displays may also be selected by using the arrow keys <Up>, <Down>, <Left>, and <Right>.
Multiple displays are selected by pressing and holding mouse button 1 somewhere on the window background. By moving the pointer while holding the button, a selection rectangle is shown; all displays fitting in the rectangle are selected when mouse button 1 is released.
If the <Shift> key is pressed while selecting, the existing selection is extended.
By double-clicking on a display title, the display itself and all connected displays are automatically selected.
Aggregate values (i.e. records, structs, classes, and arrays) can be shown expanded, that is, displaying all details, or hidden, that is, displayed as ‘{...}’.
To show details about an aggregate, select the aggregate by clicking mouse button 1 on its name or value and click on the ‘Show’ button. Details are shown for the aggregate itself as well as for all contained sub-aggregates.
To hide details about an aggregate, select the aggregate by clicking mouse button 1 on its name or value and click on the ‘Hide’ button.
When pressing and holding mouse button 1 on the ‘Show/Hide’ button, a menu pops up with even more alternatives:
Show More ()Show Just ()Show All ()Hide ()As a faster alternative, you can also press mouse button 3 on the aggregate and select the appropriate menu item.
As an even faster alternative, you can also double-click mouse button 1 on a value. If some part of the value is hidden, more details will be shown; if the entire value is shown, double-clicking will hide the value instead. This way, you can double-click on a value until you get the right amount of details.
If all details of a display are hidden, the display is called disabled; this is indicated by the string ‘(Disabled)’.
Displays can also be disabled or enabled via a DDD command, which you enter at the debugger prompt:
graph disable display displays...
disables the given displays.
graph enable display displays...
re-enables the given displays.
In both commands, displays... is either
Use ‘Edit Undo’ to undo disabling or enabling displays.
Arrays, structures and lists can be oriented horizontally or vertically. To change the orientation of a display, select it and then click on the ‘Rotate’ button.
As a faster alternative, you can also press mouse button 3 on the array and select ‘Rotate’ from the popup menu.
If a structure or list is oriented horizontally, DDD automatically suppresses the member names. This can be handy for saving space.
The last chosen display orientation is used for the creation of new displays. If you recently rotated an array to horizontal orientation, the next array you create will also be oriented horizontally. These settings are tied to the following resources:
How arrays are to be oriented. Possible values are ‘XmVERTICAL’ (default) and ‘XmHORIZONTAL’.
Whether to show struct member names or not. Default is ‘on’.
How structs are to be oriented. Possible values are ‘XmVERTICAL’ (default) and ‘XmHORIZONTAL’.
You can display all local variables at once by choosing ‘Data
Display Local Variables’. When using DBX, XDB, JDB, or Perl,
this displays all local variables, including the arguments of the
current function. When using GDB or pydb, function arguments are
contained in a separate display, activated by ‘Data
Display Arguments’.
The display showing the local variables can be manipulated just like any other data display. Individual variables can be selected and dereferenced.
You can create a display from the output of an arbitrary debugger command. By entering
graph display `command`
the output of command is turned into a status display updated each time the program stops.
For instance, the command
graph display `where`
creates a status display named ‘Where’ that shows the current backtrace.
If you are using GDB, DDD provides a panel from which you can choose useful status displays. Select ‘Data Status Displays’ and pick your choice from the list.
Refreshing status displays at each stop takes time; you should delete status displays as soon as you don't need them any more.
The data window is automatically updated or refreshed each time the program stops. Values that have changed since the last refresh are highlighted.
However, there may be situations where you should refresh the data window explicitly. This is especially the case whenever you changed debugger settings that could affect the data format, and want the data window to reflect these settings.
You can refresh the data window by selecting ‘Data Refresh Displays’.
As an alternative, you can press mouse button 3 on the background of the data window and select the ‘Refresh Displays’ item.
Typing
graph refresh
at the debugger prompt has the same effect.
By default, displays are created from top to bottom—that is, each new display is placed below the downmost one. You can change this setting to left to right via ‘Edit Preferences Data Placement Left to right’.
This setting is tied to the following resource:
If this is ‘XmVERTICAL’ (default), DDD places each new independent display below the downmost one. If this is ‘XmHORIZONTAL’, each new independent display is placed on the right of the rightmost one.
Note that changing the placement of new displays also affects the placement of dependent displays (see Dependent Values). In top to bottom mode, dependent displays are created on the right of the originating display; in left to right mode, dependent displays are created on the below the originating display.
If you examine several variables at once, having a separate display for each of them uses a lot of screen space. This is why DDD supports clusters. A cluster merges several logical data displays into one physical display, saving screen space.
There are two ways to create clusters:
Displays in a cluster can be selected and manipulated like parts of an ordinary display; in particular, you can show and hide details, or dereference pointers. However, edges leading to clustered displays can not be shown, and you must either select one or all clustered displays.
Disabling a cluster is called unclustering, and again, there are two ways of doing it:
To display several successive objects of the same type (a section of an array, or an array of dynamically determined size), you can use the notation ‘from..to’ in display expressions.
from and to are numbers that denote the first and last expression to display. Thus,
graph display argv[0..9]
creates 10 new displays for ‘argv[0]’, ‘argv[1]’, ..., ‘argv[9]’. The displays are clustered automatically (see Clustering), such that you can easily handle the set just like an array.
The ‘from..to’ notation can also be used multiple times. For instance,
graph display 1..5 * 1..5
creates a handy small multiplication table.
The ‘from..to’ notation creates several displays, which takes time to create and update. If you want to display only a part of an array, array slices are a more efficient way. See Array Slices, for a discussion.
You can view the state of all displays by selecting ‘Data Displays’. This invokes the Display Editor.
The Display Editor shows the properties of each display, using the following fields:
To delete a single display, select its title or value and click on the ‘Undisp’ button. As an alternative, you can also press mouse button 3 on the display and select the ‘Undisplay’ item.
When a display is deleted, its immediate ancestors and descendants are automatically selected, so that you can easily delete entire graphs.
If you have selected only part of a display, clicking on the ‘Undisp’ button allows you to suppress this part—by applying the Suppress Values theme on the part. You'll be asked for confirmation first. See Using Data Themes, for details.
To delete several displays at once, use the ‘Undisp’ button in the Display Editor (invoked via ‘Data Displays’). Select any number of display items in the usual way and delete them by pressing ‘Undisp’.
As an alternative, you can also use a DDD command:
graph undisplay displays...
Here, displays... is either
If you are using stacked windows, deleting the last display from the data window also automatically closes the data window. (You can change this via ‘Edit Preferences Data Close data window when deleting last display’.)
If you deleted a display by mistake, use ‘Edit Undo’ to re-create it.
Finally, you can also cut, copy, and paste displays using the ‘Cut’, ‘Copy’, and ‘Paste’ items from the ‘Edit’ menu. The clipboard holds the commands used to create the displays; ‘Paste’ inserts the display commands in the debugger console. This allows you to save displays for later usage or to copy displays across multiple DDD instances.
DDD has some special features that facilitate handling of arrays.
It is often useful to print out several successive objects of the same type in memory; a slice (section) of an array, or an array of dynamically determined size for which only a pointer exists in the program.
Using DDD, you can display slices using the ‘from..to’ notation (see Creating Multiple Displays). But this requires that you already know from and to; it is also inefficient to create several single displays. If you use GDB, you have yet another alternative.
Using GDB, you can display successive objects by referring to a contiguous span of memory as an artificial array, using the binary operator ‘@’. The left operand of ‘@’ should be the first element of the desired array and be an individual object. The right operand should be the desired length of the array. The result is an array value whose elements are all of the type of the left argument. The first element is actually the left argument; the second element comes from bytes of memory immediately following those that hold the first element, and so on.
Here is an example. If a program says
int *array = (int *) malloc (len * sizeof (int));
you can print the contents of array with
print array[0]@len
and display the contents with
graph display array[0]@len
The general form of displaying an array slice is thus
graph display array[first]@nelems
where array is the name of the array to display, first is the index of the first element, and nelems is the number of elements to display.
The left operand of ‘@’ must reside in memory. Array values made with ‘@’ in this way behave just like other arrays in terms of subscripting, and are coerced to pointers when used in expressions.
Using GDB, an array value that is repeated 10 or more times is displayed only once. The value is shown with a ‘<nx>’ postfix added, where n is the number of times the value is repeated. Thus, the display ‘0x0 <30x>’ stands for 30 array elements, each with the value ‘0x0’. This saves a lot of display space, especially with homogeneous arrays.
The default GDB threshold for repeated array values is 10. You can change it via ‘Edit GDB Settings Threshold for repeated print elements’. Setting the threshold to
0 will cause
GDB (and DDD) to display each array element individually. Be
sure to refresh the data window via ‘Data Refresh
Displays’ after a change in GDB settings.
You can also configure DDD to display each array element individually:
GDB can print repeated array elements as ‘value <repeated n times>’. If ‘expandRepeatedValues’ is ‘on’, DDD will display n instances of value instead. If ‘expandRepeatedValues’ is ‘off’ (default), DDD will display value with ‘<nx>’ appended to indicate the repetition.
By default, DDD lays out two-dimensional arrays as tables, such that all array elements are aligned with each other.27 To disable this feature, unset ‘Edit Preferences Data Display Two-Dimensional Arrays as Tables’. This is tied to the following resource:
If ‘on’ (default), DDD lays out two-dimensional arrays as tables, such that all array elements are aligned with each other. If ‘off’, DDD treats a two-dimensional array as an array of one-dimensional arrays, each aligned on its own.
During program execution, you can change the values of arbitrary variables.28
To change the value of a variable, enter its name in ‘()’—for instance, by selecting an occurrence or a display. Then, click on the ‘Set’ button. In a dialog, you can edit the variable value at will; clicking the ‘OK’ or ‘Apply’ button commits your change and assigns the new value to the variable.
To change a displayed value, you can also select ‘Set Value’ menu from the data popup menu,
If you made a mistake, you can use ‘Edit Undo’ to re-set the variable to its previous value.
Besides displaying simple values, DDD can also visualize the Dependencies between values—especially pointers and other references that make up complex data structures.
Dependent displays are created from an existing display. The dependency is indicated by an edge leading from the originating display to the dependent display.
To create a dependent display, select the originating display or display part and enter the dependent expression in the ‘():’ argument field. Then click on the ‘Display’ button.
Using dependent displays, you can investigate the data structure of a tree for example and lay it out according to your intuitive image of the tree data structure.
By default, DDD does not recognize shared data structures (i.e. a data object referenced by multiple other data objects). See Shared Structures, for details on how to examine such structures.
There are special shortcuts for creating dependent displays showing the value of a dereferenced pointer. This allows for rapid examination of pointer-based data structures.
To dereference a pointer, select the originating pointer value or name and click on the ‘Disp *’ button. A new display showing the dereferenced pointer value is created.
As a faster alternative, you can also press mouse button 3 on the originating pointer value or name and select the ‘Display *’ menu item.
As an even faster alternative, you can also double-click mouse button 1 on the originating pointer value or name. If you press <Ctrl> while double-clicking, the display will be dereferenced in place–that is, it will be replaced by the dereferenced display.
The ‘Display *()’ function is also accessible by pressing and holding the ‘Display’ button.
By default, DDD does not recognize shared data structures—that is, a data object referenced by multiple other data objects. For instance, if two pointers ‘p1’ and ‘p2’ point at the same data object ‘d’, the data displays ‘d’, ‘*p1’, and ‘*p2’ will be separate, although they denote the same object.
DDD provides a special mode which makes it detect these situations. DDD recognizes if two or more data displays are stored at the same physical address, and if this is so, merges all these aliases into one single data display, the original data display. This mode is called Alias Detection; it is enabled via ‘Data Detect Aliases’.
When alias detection is enabled, DDD inquires the memory location (the address) of each data display after each program step. If two displays have the same address, they are merged into one. More specifically, only the one which has least recently changed remains (the original data display); all other aliases are suppressed, i.e. completely hidden. The edges leading to the aliases are replaced by edges leading to the original data display.
An edge created by alias detection is somewhat special: rather than connecting two displays directly, it goes through an edge hint, describing an arc connecting the two displays and the edge hint.
Each edge hint is a placeholder for a suppressed alias; selecting an edge hint is equivalent to selecting the alias. This way, you can easily delete display aliases by simply selecting the edge hint and clicking on ‘Undisp’.
To access suppressed display aliases, you can also use the Display Editor. Suppressed displays are listed in the Display Editor as aliases of the original data display. Via the Display Editor, you can select, change, and delete suppressed displays.
Suppressed displays become visible again as soon as
Please note the following caveats with alias detection:
Alias detection is controlled by the following resources:
If this is ‘on’ (default), the ‘Undisplay ()’ button also deletes all aliases of the selected displays. If this is ‘off’, only the selected displays are deleted; the aliases remain, and one of the aliases will be unsuppressed.
If ‘on’ (default), DDD attempts to recognize shared data structures. If ‘off’, shared data structures are not recognized.
If ‘on’ (default), DDD requires structural equivalence in order to recognize shared data structures. If this is ‘off’, two displays at the same address are considered aliases, regardless of their structure.
DDD maintains a shortcut menu of frequently used display expressions. This menu is activated
By default, the shortcut menu contains frequently used base conversions.
The ‘Other’ entry in the shortcut menu lets you create a new display that extends the shortcut menu.
As an example, assume you have selected a display named ‘date_ptr’. Selecting ‘Display Other’ pops up a dialog that allows you to enter a new expression to be displayed—for instance, you can cast the display ‘date_ptr’ to a new display ‘(char *)date_ptr’. If the ‘Include in ‘New Display’ Menu’ toggle was activated, the shortcut menu will then contain a new entry ‘Display (char *)()’ that will cast any selected display display to ‘(char *)display’. Such shortcuts can save you a lot of time when examining complex data structures.
You can edit the contents of the ‘New Display’ menu by selecting its ‘Edit Menu’ item. This pops up the Shortcut Editor containing all shortcut expressions, which you can edit at leisure. Each line contains the expression for exactly one menu item. Clicking on ‘Apply’ re-creates the ‘New Display’ menu from the text. If the text is empty, the ‘New Display’ menu will be empty, too.
DDD also allows you to specify individual labels for user-defined buttons. You can write such a label after the expression, separated by ‘//’. This feature is used in the default contents of the GDB ‘New Display’ menu, where each of the base conversions has a label:
/t () // Convert to Bin
/d () // Convert to Dec
/x () // Convert to Hex
/o () // Convert to Oct
Feel free to add other conversions here. DDD supports up to 20 ‘New Display’ menu items.
The shortcut menu is controlled by the following resources:
A newline-separated list of display expressions to be included in the ‘New Display’ menu for DBX.
If a line contains a label delimiter29, the string before the delimiter is used as expression, and the string after the delimiter is used as label. Otherwise, the label is ‘Display expression’. Upon activation, the string ‘()’ in expression is replaced by the name of the currently selected display.
A newline-separated list of display expressions to be included in the ‘New Display’ menu for GDB. See the description of ‘dbxDisplayShortcuts’, above.
A newline-separated list of display expressions to be included in the ‘New Display’ menu for JDB. See the description of ‘dbxDisplayShortcuts’, above.
A newline-separated list of display expressions to be included in the ‘New Display’ menu for Perl. See the description of ‘dbxDisplayShortcuts’, above.
A newline-separated list of display expressions to be included in the ‘New Display’ menu for Bash. See the description of ‘dbxDisplayShortcuts’, above.
A newline-separated list of display expressions to be included in the ‘New Display’ menu for
pydb. See the description of ‘dbxDisplayShortcuts’, above.
A newline-separated list of display expressions to be included in the ‘New Display’ menu for XDB. See the description of ‘dbxDisplayShortcuts’, above.
DDD provides a simple method to customize displays. DDD comes with a number of visual modifiers, called data themes.
Each theme modifies a particular aspect of a data display. It can be applied to individual displays or to a number of displays. The themes installed with DDD include:
*\[*\] to make
all array members tiny.
Apply this theme to display values in a tiny font.
*->X to suppress all members named
`X'. Apply this theme to display values not at all.
graph apply red.vsl "()"
graph apply green.vsl "()".
Ddd*dataButtons: \
graph display ($eflags & 1) != 0 // c\n\
graph display ($eflags & 64) != 0 // z\n\
graph display ($eflags & 128) != 0 // s\n\
graph display ($eflags & 1024) != 0 // d\n\
graph display ($eflags & 2048) != 0 // o\n\
graph display $eax & 255 // al\n\
graph display $eax >> 8 & 255 // ah\n\
graph display $eax & 65535 // ax\n\
graph display $ebx & 255 // bl\n\
graph display $ebx >> 8 & 255 // bh\n\
graph display $ebx & 65535 // bx\n\
graph display $ecx & 255 // cl\n\
graph display $ecx >> 8 & 255 // ch\n\
graph display $ecx & 65535 // cx\n\
graph display $edx & 255 // dl\n\
graph display $edx >> 8 & 255 // dh\n\
graph display $edx & 65535 // dx
Whenever the these displays is shown, the title will be replaced by a more intuitive title like “carry”, or “zero” for one of the flag bits and “al” “ax”, etc. for one of the registers.
Each of these themes can be applied for specific displays.
To apply a theme on a display,
For instance, to display the variable s in a tiny font, click
mouse button 3 on the display of s, and select ‘Theme
Tiny Values Apply’.
To unapply a theme, just click on ‘Undo’ (if you just applied it) or repeat the sequence as above.
Whenever you want to apply a theme on a struct member or an array element, you will be asked whether to
Suppose, for instance, that you don't want to see ‘vptr’ members anymore. Then you'd apply the theme Suppress Values on all similar values.
On the other hand, if you want to highlight one single value only, you'd apply the theme Red Background on only one single value.
If you find this confirmation annoying, you can define a command button which directly applies the theme. See Defining Commands, for details on defining commands.
Applying and unapplying themes is associated with the following commands:
graph apply theme name pattern
applies the theme name on pattern.
graph unapply theme name pattern
unapplies the theme name on pattern.
graph toggle theme name pattern
applies the theme name on pattern if it was not already applied, and unapplies it otherwise.
Each theme can be globally activated or not. If a theme is activated, it is applied to all expressions that match its pattern.
Normally, these patterns are automatically maintained by simply selecting the themes for the individual displays. However, you can also edit patterns directly.
Patterns are separated by ‘;’ and contain shell-like metacharacters:
To edit the set of themes, invoke ‘Data Themes’.
To apply changes you made to the themes, click on ‘Apply’. To revert the themes to the last saved, click on ‘Reset’.
You can write your own data themes, customizing the display to match your need. See Top, for details.
You can use these resources to control display appearance:
If this is ‘on’ (default) and DDD is in stacked window mode, deleting the last display automatically closes the data window. If this is ‘off’, the data window stays open even after deleting the last display.
If some display d changes size and this resource is ‘on’ (default), DDD assigns new positions to displays below and on the right of d such that the distance between displays remains constant. If this is ‘off’, other displays are not rearranged.
If ‘on’, new independent data displays will automatically be clustered. Default is ‘off’, meaning to leave new displays unclustered.
If some display gets out of scope and this resource is ‘on’ (default), DDD removes it from the data display. If this is ‘off’, it is simply disabled.
Whether to assign titles to base (independent) displays or not. Default is ‘on’.
Whether to assign titles to dependent displays or not. Default is ‘off’.
The theme to apply when selecting ‘Undisp’ on a data value. Default is suppress.vsl.
A newline-separated list of themes. Each theme has the format name, tabulator character, pattern.
The following resources control the VSL interpreter:
A string with additional VSL definitions that are appended to the builtin VSL library. This resource is prepended to the ‘vslDefs’ resource below and set in the DDD application defaults file; don't change it.
A string with additional VSL definitions that are appended to the builtin VSL library. The default value is an empty string. This resource can be used to override specific VSL definitions that affect the data display. The preferred method, though, is to write a specific data theme (see Writing Data Themes).
The VSL library to use. ‘builtin’ (default) means to use the built-in library, any other value is used as file name.
A colon-separated list of directories to search for VSL include files. The following directory names are special:
Default is ‘user_themes:ddd_themes:.’, which means that DDD first searches your theme directory, followed by the system directory and the current directory.
- The special directory name ‘user_themes’ stands for your individual theme directory, typically ~/.ddd/themes/.
- The special directory name ‘ddd_themes’ stands for the installed theme directory, typically /usr/local/share/ddd-3.3.12/themes/.
If your DDD source distribution is installed in /opt/src, you can use the following settings to read the VSL library from /home/joe/ddd.vsl:
Ddd*vslLibrary: /home/joe/ddd.vsl
Ddd*vslPath: user_themes:.:/opt/src/ddd/ddd:/opt/src/ddd/vsllib
VSL include files referenced by /home/joe/ddd.vsl are searched first in the current directory ., then in your theme directory, then in /opt/src/ddd/ddd/, and then in /opt/src/ddd/vsllib/.
Instead of supplying another VSL library, it is often easier to specify some minor changes to the built-in library (see Writing Data Themes).
If you have several displays at once, you may wish to arrange them according to your personal preferences. This section tells you how you can do this.
From time to time, you may wish to move displays at another place in the data window. You can move a single display by pressing and holding mouse button 1 on the display title. Moving the pointer while holding the button causes all selected displays to move along with the pointer.
Edge hints can be selected and moved around like other displays. If an arc goes through the edge hint, you can change the shape of the arc by moving the edge hint around.
For fine-grain movements, selected displays may also be moved using the arrow keys. Pressing <Shift> and an arrow key moves displays by single pixels. Pressing <Ctrl> and arrow keys moves displays by grid positions.
If the data window becomes too small to hold all displays, scroll bars are created. If your DDD is set up to use panners instead, a panner is created in the lower right edge. When the panner is moved around, the window view follows the position of the panner.
To change from scroll bars to panners, use ‘Edit Startup Data Scrolling’ and choose either ‘Panner’ or ‘Scrollbars’. This setting is tied to the following resource:
The control to scroll the graph.
- If this is ‘on’, an Athena panner is used (a kind of two-directional scrollbar).
- If this is ‘off’ (default), two M*tif scrollbars are used.
See Options, for the --scrolled-graph-editor and --panned-graph-editor options.
You can align all displays on the nearest grid position by selecting ‘Data Align on Grid’. This is useful for keeping edges strictly horizontal or vertical.
You can enforce alignment by selecting ‘Edit Preferences Data Auto-align Displays on Nearest Grid Point’. If this feature is enabled, displays can be moved on grid positions only.
You can layout the entire graph as a tree by selecting ‘Data Layout Graph’. The layout direction is determined from the display placement (see Placement) and from the last rotation (see Rotating the Graph).
Layouting the graph may introduce edge hints; that is, edges are no more straight lines, but lead to an edge hint and from there to their destination. Edge hints can be moved around like arbitrary displays.
To enable a more compact layout, you can set the ‘Edit Preferences Data Compact Layout’ option. This realizes an alternate layout algorithm, where successors are placed next to their parents. This algorithm is suitable for homogeneous data structures only.
You can enforce layout by setting ‘Edit Preferences Data Automatic Layout’. If automatic layout is enabled, the graph is layouted after each change.
You can rotate the entire graph clockwise by 90 degrees by selecting ‘Data Rotate Graph’. You may need to layout the graph after rotating it; See Automatic Layout, for details.
DDD allows for printing the graph picture on PostScript printers or into files. This is useful for documenting program states.
To print the graph on a PostScript printer, select ‘File Print Graph’. Enter the printing command in the ‘Print Command’ field. Click on the ‘OK’ or the ‘Apply’ button to start printing.
As an alternative, you may also print the graph in a file. Click on the ‘File’ button and enter the file name in the ‘File Name’ field. Click on the ‘Print’ button to create the file.
When the graph is printed in a file, two formats are available:
Please note the following caveats related to printing graphs:
These settings are tied to the following resources:
The command to print a PostScript file. Usually ‘lp’ or ‘lpr’.
The paper size used for printing, in format ‘width x height’. The default is ISO A4 format, or ‘210mm x 297mm’.
If you have huge amounts of numerical data to examine, a picture often says more than a thousand numbers. Therefore, DDD allows you to draw numerical values in nice 2-D and 3-D plots.
Basically, DDD can plot two types of numerical values:
To plot a fixed-size array, select its name by clicking mouse button 1 on an occurrence. The array name is copied to the argument field. By clicking the ‘Plot’ button, a new display is created in the data window, followed by a new top-level window containing the value plot.
To plot a dynamically sized array, you must use an array slice (see Array Slices). In the argument field, enter
array[first]@nelems
where array is the name of the array to display, first is the index of the first element, and nelems is the number of elements to display. Then, click on ‘Plot’ to start the plot.
To plot a value, you can also enter a command at the debugger prompt:
graph plot expr
works like ‘graph display expr’ (and takes the same arguments; see Creating Single Displays), but the value is additionally shown in the plot window.
Each time the value changes during program execution, the plot is updated to reflect the current values. The plot window remains active until you close it (via ‘File Close’) or until the associated display is deleted.
The actual drawing is not done by DDD itself. Instead, DDD relies on an external gnuplot program to create the drawing.
DDD adds a menu bar to the Gnuplot plot window that lets you influence the appearance of the plot:
In a 3-D plot, you can use the scroll bars to change your view position. The horizontal scroll bar rotates the plot around the z axis, that is, to the left and right. The vertical scroll bar rotates the plot around the y axis, that is, up and down.
You can also resize the plot window as desired.
Besides plotting arrays, DDD also allows you to plot scalars (simple numerical values). This works just like plotting arrays—you select the numerical variable, click on ‘Plot’, and here comes the plot. However, plotting a scalar is not very exciting. A plot that contains nothing but a scalar simply draws the scalar's value as a y constant—that is, a horizontal line.
So why care about scalars at all? DDD allows you to combine multiple values into one plot. The basic idea is: if you want to plot something that is neither an array nor a scalar, DDD takes all numerical sub-values it can find and plots them all together in one window. For instance, you can plot all local variables by selecting ‘Data Display Local Variables’, followed by ‘Plot’. This will create a plot containing all numerical values as found in the current local variables. Likewise, you can plot all numeric members contained in a structure by selecting it, followed by ‘Plot’.
If you want more control about what to include in a plot and what not, you can use display clusters (see Clustering). A common scenario is to plot a one-dimensional array together with the current index position. This is done in three steps:
Scalars that are displayed together with arrays can be displayed either as vertical lines or horizontal lines. By default, scalars are plotted as horizontal lines. However, if a scalar is a valid index for an array that was previously plotted, it is shown as a vertical line. You can change this initial orientation by selecting the scalar display, followed by ‘Rotate’.
At each program stop, DDD records the values of all displayed variables, such that you can “undo” program execution (see Undoing Program Execution). These display histories can be plotted, too. The menu item ‘Plot Plot history of ()’ creates a plot that shows all previously recorded values of the selected display.
If you want to print the plot, select ‘File Print Plot’. This pops up the DDD printing dialog, set up for printing plots. Just as when printing graphs, you have the choice between printing to a printer or a file and setting up appropriate options.
The actual printing is also performed by Gnuplot, using the appropriate driver. Please note the following caveats related to printing:
Via ‘File Command’, you can enter Gnuplot commands directly. Each command entered at the ‘gnuplot>’ prompt is passed to Gnuplot, followed by a Gnuplot ‘replot’ command to update the view. This is useful for advanced Gnuplot tasks.
Here's a simple example. The Gnuplot command
set xrange [xmin:xmax]
sets the horizontal range that will be displayed to xmin...xmax. To plot only the elements 10 to 20, enter:
gnuplot> set xrange [10:20]
gnuplot> _
After each command entered, DDD adds a replot command, such that the plot is updated automatically.
Here's a more complex example. The following sequence of Gnuplot commands saves the plot in TeX format:
gnuplot> set output "plot.tex" # Set the output filename
gnuplot> set term latex # Set the output format
gnuplot> set term x11 # Show original picture again
gnuplot> _
Due to the implicit replot command, the output is automatically written to ‘plot.tex’ after the set term latex command.
The dialog keeps track of the commands entered; use the arrow keys to restore previous commands. Gnuplot error messages (if any) are also shown in the history area.
The interaction between DDD and Gnuplot is logged in the file ~/.ddd/log (see Logging). The DDD --trace option logs this interaction on standard output.
If you want some external program to process the plot data (a stand-alone Gnuplot program or the xmgr program, for instance), you can save the plot data in a file, using ‘File Save Data As’. This pops up a dialog that lets you choose a data file to save the plotted data in.
The generated file starts with a few comment lines. The actual data follows in X/Y or X/Y/Z format. It is the same file as processed by Gnuplot.
If you want to see how your data evolves in time, you can set a breakpoint whose command sequence ends in a cont command (see Breakpoint Commands. Each time this “continue” breakpoint is reached, the program stops and DDD updates the displayed values, including the plots. Then, DDD executes the breakpoint command sequence, resuming execution.
This way, you can set a “continue” breakpoint at some decisive point within an array-processing algorithm and have DDD display the progress graphically. When your program has stopped for good, you can use ‘Undo’ and ‘Redo’ to redisplay and examine previous program states. See Undoing Program Execution, for details.
You can customize the Gnuplot program to invoke, as well as a number of basic settings.
Using ‘Edit Preferences Helpers Plot’, you can choose the Gnuplot program to invoke. This is tied to the following resource:
The name of a Gnuplot executable. Default is ‘gnuplot’, followed by some options to set up colors and the initial geometry.
Using ‘Edit Preferences Helpers Plot Window’, you can choose whether to use the Gnuplot plot window (‘External’) or to use the plot window supplied by DDD (‘builtin’). This is tied to the following resource:
The Gnuplot terminal type. Can have one of two values:
- If this is ‘x11’, DDD “swallows” the external Gnuplot output window into its own user interface. Some window managers, notably mwm, have trouble with swallowing techniques.
- Setting this resource to ‘xlib’ (default) makes DDD provide a builtin plot window instead. In this mode, plots work well with any window manager, but are less customizable (Gnuplot resources are not understood).
You can further control interaction with the external plot window:
The class of the Gnuplot output window. When invoking Gnuplot, DDD waits for a window with this class and incorporates it into its own user interface (unless ‘plotTermType’ is ‘xlib’; see above). Default is ‘Gnuplot’.
The time (in ms) to wait for the creation of the Gnuplot window. Before this delay, DDD looks at each newly created window to see whether this is the plot window to swallow. This is cheap, but unfortunately, some window managers do not pass the creation event to DDD. If this delay has passed, and DDD has not found the plot window, DDD searches all existing windows, which is pretty expensive. Default time is
2000.
To change Gnuplot settings, use these resources:
The initial Gnuplot commands issued by DDD. Default is:
set parametric set urange [0:1] set vrange [0:1] set trange [0:1]The ‘parametric’ setting is required to make Gnuplot understand the data files as generated DDD. The range commands are used to plot scalars.
See the Gnuplot documentation for additional commands.
Additional initial settings for 2-D plots. Default is ‘set noborder’. Feel free to customize these settings as desired.
Additional initial settings for 3-D plots. Default is ‘set border’. Feel free to customize these settings as desired.
Using GDB or DBX, you can examine memory in any of several formats, independently of your program's data types. The item ‘Data Memory’ pops up a panel where you can choose the format to be shown.
In the panel, you can enter
There are two ways to examine the values:
Sometimes, it is desirable to examine a program not only at the source level, but also at the machine level. DDD provides special machine code and register windows for this task.
To enable machine-level support, select ‘Source Display Machine Code’. With machine code enabled, an additional machine code window shows up, displaying the machine code of the current function.30 By moving the sash at the right of the separating line between source and machine code, you can resize the source and machine code windows.
The machine code window works very much like the source window. You can set, clear, and change breakpoints by selecting the address and pressing a ‘Break’ or ‘Clear’ button; the usual popup menus are also available. Breakpoints and the current execution position are displayed simultaneously in both source and machine code.
The ‘Lookup’ button can be used to look up the machine code for a specific function—or the function for a specific address. Just click on the location in one window and press ‘Lookup’ to see the corresponding code in the other window.
If source code is not available, only the machine code window is updated.
You can customize various aspects of the disassembling window. See Customizing Machine Code, for details.
All execution facilities available in the source code window are available in the machine code window as well. Two special facilities are convenient for machine-level debugging:
To execute just one machine instruction, click on the ‘Stepi’ button or select ‘Program Step Instruction’.
To continue to the next instruction in the current function, click on the ‘Nexti’ button select ‘Program Next Instruction’.. This is similar to ‘Stepi’, but any subroutine calls are executed without stopping.
Using GDB, it is often useful to do
graph display /i $pc
when stepping by machine instructions. This makes DDD automatically display the next instruction to be executed, each time your program stops.
DDD provides a register window showing the machine register values after each program stop. To enable the register window, select ‘Status Registers’.31
By selecting one of the registers, its name is copied to the argument field. You can use it as value for ‘Display’, for instance, to have its value displayed in the data window.
Enabling machine code via ‘Source Display Machine Code’ (see Machine Code) toggles the following resource:
If this is ‘on’, the source code is automatically disassembled. The default is ‘off’. See Options, for the --disassemble and --no-disassemble options.
You can keep disassembled code in memory, using ‘Edit Preferences Source Cache Machine Code’:
Whether to cache disassembled machine code (‘on’, default) or not (‘off’). Caching machine code requires more memory, but makes DDD run faster.
You can control the indentation of machine code, using ‘Edit Preferences Source Machine Code Indentation’:
The number of columns to indent the machine code, such that there is enough place to display breakpoint locations. Default:
4.
The ‘maxDisassemble’ resource controls how much is to be disassembled. If ‘maxDisassemble’ is set to 256 (default) and the current function is larger than 256 bytes, DDD only disassembles the first 256 bytes below the current location. You can set the ‘maxDisassemble’ resource to a larger value if you prefer to have a larger machine code view.
Maximum number of bytes to disassemble (default:
256). If this is zero, the entire current function is disassembled.
DDD offers some basic facilities to edit and recompile the source code, as well as patching executables and core files.
In DDD itself, you cannot change the source file currently displayed. Instead, DDD allows you to invoke a text editor. To invoke a text editor for the current source file, select the ‘Edit’ button or ‘Source Edit Source’.
By default, DDD tries a number of common editors. You can customize DDD to use your favorite editor; See Customizing Editing, for details.
After the editor has exited, the source code shown is automatically updated.
If you have DDD and an editor running in parallel, you can also update the source code manually via ‘Source Reload Source’. This reloads the source code shown from the source file. Since DDD automatically reloads the source code if the debugged program has been recompiled, this should seldom be necessary.
You can customize the editor to be used via ‘Edit Preferences Helpers Edit Sources’. This is tied to the following resource:
A command string to invoke an editor on the specific file. ‘@LINE@’ is replaced by the current line number, ‘@FILE@’ by the file name. The default is to invoke $XEDITOR first, then $EDITOR, then vi:
Ddd*editCommand: \ ${XEDITOR-false} +@LINE@ @FILE@ || \ xterm -e ${EDITOR-vi} +@LINE@ @FILE@
This ~/.ddd/init setting invokes an editing session for an XEmacs editor running gnuserv:
Ddd*editCommand: gnuclient +@LINE@ @FILE@
This ~/.ddd/init setting invokes an editing session for an Emacs editor running emacsserver:
Ddd*editCommand: emacsclient +@LINE@ @FILE@
This resource is experimental:
If this is ‘on’, the displayed source code becomes editable. This is an experimental feature; Default is ‘off’.
To recompile the source code using make, you can select ‘File Make’. This pops up a dialog where you can enter a Make Target—typically the name of the executable. Clicking on the ‘Make’ button invokes the make program with the given target.
The ‘Make’ button on the command tool re-invokes make with the most recently given arguments.
Using GDB, you can open your program's executable code (and the core file) for both reading and writing. This allows alterations to machine code, such that you can intentionally patch your program's binary. For example, you might want to turn on internal debugging flags, or even to make emergency repairs.
Note that depending on your operating system, special preparation steps, such as setting permissions, may be needed before you can change executable files.
To patch the binary, enable ‘Edit GDB Settings Writing into executable and core files’. This makes GDB open executable and core files for both reading and writing. If you have already loaded a file, you must load it again (using ‘Edit Open File’ or ‘Edit Open Core’), for your new setting to take effect.
Be sure to turn off ‘Writing into executable and core files’ as soon as possible, to prevent accidental alterations to machine code.
All the buttons you click within DDD get eventually translated into some debugger command, shown in the debugger console. You can also type in and edit these commands directly.
In the debugger console, you can interact with the command
interface of the inferior debugger. Enter commands at the
debugger prompt—that is,
‘(gdb)’ for GDB,
‘bashdb<>’ for Bash,
‘(dbx)’ for DBX,
‘>’ ‘thread[depth]’ for JDB,
‘(ladebug)’ for Ladebug,
‘mdb<>’ for the GNU Make debugger,
‘DB<>’ for Perl,
‘(Pydb)’ for pydb,
or ‘>’ for XDB.
You can use arbitrary debugger commands; use the
<Return> key to enter them.
When using GDB or Perl, you can use the <TAB> key for completing commands and arguments. This works in the debugger console as well as in all other text windows.
GDB can fill in the rest of a word in a command for you, if there is only one possibility; it can also show you what the valid possibilities are for the next word in a command, at any time. This works for GDB commands, GDB subcommands, and the names of symbols in your program.
Press the <TAB> key whenever you want GDB to fill out the rest of a word. If there is only one possibility, GDB fills in the word, and waits for you to finish the command (or press <RET> to enter it). For example, if you type
(gdb) info bre_<TAB>
GDB fills in the rest of the word ‘breakpoints’, since that is the only info subcommand beginning with ‘bre’:
(gdb) info breakpoints
You can either press <RET> at this point, to run the info breakpoints command, or backspace and enter something else, if ‘breakpoints’ does not look like the command you expected. (If you were sure you wanted info breakpoints in the first place, you might as well just type <RET> immediately after ‘info bre’, to exploit command abbreviations rather than command completion).
If there is more than one possibility for the next word when you press <TAB>, DDD sounds a bell. You can either supply more characters and try again, or just press <TAB> a second time; GDB displays all the possible completions for that word. For example, you might want to set a breakpoint on a subroutine whose name begins with ‘make_’, but when you type b make_<TAB>, DDD just sounds the bell. Typing <TAB> again displays all the function names in your program that begin with those characters. If you type <TAB> again, you cycle through the list of completions, for example:
(gdb) b make_ <TAB>
DDD sounds bell; press <TAB> again, to see:
make_a_section_from_file make_environ make_abs_section make_function_type make_blockvector make_pointer_type make_cleanup make_reference_type make_command make_symbol_completion_list (gdb) b make_ <TAB>
DDD presents one expansion after the other:
(gdb) b make_a_section_from_file <TAB> (gdb) b make_abs_section <TAB> (gdb) b make_blockvector <TAB>
After displaying the available possibilities, GDB copies your partial input (‘b make_’ in the example) so you can finish the command—by pressing <TAB> again, or by entering the remainder manually.
Sometimes the string you need, while logically a “word”, may contain
parentheses or other characters that GDB normally excludes from its
notion of a word. To permit word completion to work in this situation,
you may enclose words in ' (single quote marks) in GDB commands.
The most likely situation where you might need this is in typing the
name of a C++ function. This is because C++ allows function overloading
(multiple definitions of the same function, distinguished by argument
type). For example, when you want to set a breakpoint you may need to
distinguish whether you mean the version of name that takes an
int parameter, name(int), or the version that takes a
float parameter, name(float). To use the word-completion
facilities in this situation, type a single quote ' at the
beginning of the function name. This alerts GDB that it may need to
consider more information than usual when you press <TAB> to request
word completion:
(gdb) b 'bubble(_<TAB>
bubble(double,double) bubble(int,int)
(gdb) b 'bubble(_
In some cases, DDD can tell that completing a name requires using quotes. When this happens, DDD inserts the quote for you (while completing as much as it can) if you do not type the quote in the first place:
(gdb) b bub_<TAB>
DDD alters your input line to the following, and rings a bell:
(gdb) b 'bubble(_
In general, DDD can tell that a quote is needed (and inserts it) if you have not yet started typing the argument list when you ask for completion on an overloaded symbol.
If you prefer to use the <TAB> key for switching between items, unset ‘Edit Preferences General TAB Key completes in All Windows’. This is useful if you have pointer-driven keyboard focus (see below) and no special usage for the <TAB> key. If the option is set, the <TAB> key completes in the debugger console only.
This option is tied to the following resource:
If this is ‘on’ (default), the <TAB> key completes arguments in all windows. If this is ‘off’, the <TAB> key completes arguments in the debugger console only.
You can repeat previous and next commands by pressing the <Up> and <Down> arrow keys, respectively. This presents you previous and later commands on the command line; use <Return> to apply the current command.
If you enter an empty line (just use <Return> at the debugger prompt), the last command is repeated as well.
‘Commands Command History’ shows the command history.
You can search for previous commands by pressing <Ctrl+B>. This invokes incremental search mode, where you can enter a string to be searched in previous commands. Press <Ctrl+B> again to repeat the search, or <Ctrl+F> to search in the reverse direction. To return to normal mode, press <ESC>, or use any cursor command.
The command history is automatically saved when exiting DDD. You can turn off this feature by setting the following resource to ‘off’:
If ‘on’ (default), the command history is automatically saved when DDD exits.
As a special convenience, anything you type into the source window is automatically forwarded to the debugger console. Thus, you don't have to change the keyboard focus explicitly in order to enter commands.
You can change this behaviour using the following resource:
If ‘on’ (default), all keyboard events in the source window are automatically forwarded to the debugger console. If ‘off’, keyboard events are not forwarded. If ‘auto’, keyboard events forwarded only if the debugger console is open.
Rather than entering commands at the debugger console, you may prefer to enter commands at the terminal window DDD was invoked from.
When DDD is invoked using the --tty option, it enables its TTY interface, taking additional debugger commands from standard input and forwarding debugger output to standard output, just as if the inferior debugger had been invoked directly. All remaining DDD functionality stays unchanged.
By default, the debugger console remains closed if DDD is invoked using the --tty option. Use ‘View Debugger Console’ to open it.
DDD can be configured to use the ‘readline’ library for reading in commands from standard input. This GNU library provides consistent behavior for programs which provide a command line interface to the user. Advantages are GNU Emacs-style or vi-style inline editing of commands, csh-like history substitution, and a storage and recall of command history across debugging sessions. See Command Line Editing, for details on command-line editing via the TTY interface.
You can run DDD as an inferior debugger in other debugger front-ends, combining their special abilities with those of DDD.
To have DDD run as an inferior debugger in other front-ends, the general idea is to set up your debugger front-end such that ‘ddd --tty’ is invoked instead of the inferior debugger. When DDD is invoked using the --tty option, it enables its TTY interface, taking additional debugger commands from standard input and forwarding debugger output to standard output, just as if the inferior debugger had been invoked directly. All remaining DDD functionality stays unchanged.
In case your debugger front-end uses the GDB -fullname option to have GDB report source code positions, the --tty option is not required. DDD recognizes the -fullname option, finds that it has been invoked from a debugger front-end and automatically enables the TTY interface.
If DDD is invoked with the -fullname option, the debugger console and the source window are initially disabled, as their facilities are supposed to be provided by the integrating front-end. In case of need, you can use the ‘View’ menu to re-enable these windows.
To integrate DDD with Emacs, use M-x gdb or M-x dbx in Emacs to start a debugging session. At the prompt, enter ddd --tty (followed by --dbx or --gdb, if required), and the name of the program to be debugged. Proceed as usual.
To integrate DDD with XEmacs, set the variable
gdb-command-name to ‘"ddd"’, by inserting the following line
in your ~/.emacs file:
(setq gdb-command-name "ddd")
You can also evaluate this expression by pressing <ESC> <:> and entering it directly (<ESC> <ESC> for XEmacs 19.13 and earlier).
To start a DDD debugging session in XEmacs, use ‘M-x gdb’ or ‘M-x gdbsrc’. Proceed as usual.
To integrate DDD with XXGDB, invoke xxgdb as
xxgdb -db_name ddd -db_prompt '(gdb) '
To facilitate interaction, you can add own command buttons to DDD. These buttons can be added below the debugger console (‘Console Buttons’), the source window (‘Source Buttons’), or the data window (‘Data Buttons’).
To define individual buttons, use the Button Editor, invoked via ‘Commands Edit Buttons’. The button editor displays a text, where each line contains the command for exactly one button. Clicking on ‘OK’ creates the appropriate buttons from the text. If the text is empty (the default), no button is created.
As a simple example, assume you want to create a ‘print i’ button. Invoke ‘Commands Edit Buttons’ and enter a line saying ‘print i’ in the button editor. Then click on ‘OK’. A button named ‘Print i’ will now appear below the debugger console—try it! To remove the button, reopen the button editor, clear the ‘print i’ line and press ‘OK’ again.
If a button command contains ‘()’, the string ‘()’ will automatically be replaced by the contents of the argument field. For instance, a button named ‘return ()’ will execute the GDB ‘return’ command with the current content of the argument field as argument.
By default, DDD disables buttons whose commands are not supported by the inferior debugger. To enable such buttons, unset the ‘Enable supported buttons only’ toggle in the button editor.
DDD also allows you to specify control sequences and special labels for user-defined buttons. See Customizing Buttons, for details.
DDD allows defining additional command buttons; See Defining Buttons, for doing this interactively. This section describes the resources that control user-defined buttons.
A newline-separated list of buttons to be added under the debugger console. Each button issues the command given by its name.
The following characters have special meanings:
- Commands ending with
...insert their name, followed by a space, in the debugger console.- Commands ending with a control character (that is, ‘^’ followed by a letter or ‘?’) insert the given control character.
- The string ‘()’ is replaced by the current contents of the argument field ‘()’.
- The string specified in the ‘labelDelimiter’ resource (usually ‘//’) separates the command name from the button label. If no button label is specified, the capitalized command will be used as button label.
The following button names are reserved:
- ‘Apply’
- Send the given command to the debugger.
- ‘Back’
- Lookup previously selected source position.
- ‘Clear’
- Clear current command
- ‘Complete’
- Complete current command.
- ‘Edit’
- Edit current source file.
- ‘Forward’
- Lookup next selected source position.
- ‘Make’
- Invoke the ‘make’ program, using the most recently given arguments.
- ‘Next’
- Show next command
- ‘No’
- Answer current debugger prompt with ‘no’. This button is visible only if the debugger asks a yes/no question.
- ‘Prev’
- Show previous command
- ‘Reload’
- Reload source file.
- ‘Yes’
- Answer current debugger prompt with ‘yes’. This button is visible only if the debugger asks a yes/no question.
The default resource value is empty—no console buttons are created.
Here are some examples to insert into your ~/.ddd/init file. These are the settings of DDD 1.x:
Ddd*consoleButtons: Yes\nNo\nbreak^CThis setting creates some more buttons:
Ddd*consoleButtons: \ Yes\nNo\nrun\nClear\nPrev\nNext\nApply\nbreak^CSee also the ‘dataButtons’, ‘sourceButtons’ and ‘toolButtons’ resources.
A newline-separated list of buttons to be added under the data display. Each button issues the command given by its name. See the ‘consoleButtons’ resource, above, for details on button syntax.
The default resource value is empty—no source buttons are created.
A newline-separated list of buttons to be added under the debugger console. Each button issues the command given by its name. See the ‘consoleButtons’ resource, above, for details on button syntax.
The default resource value is empty—no source buttons are created.
Here are some example to insert into your ~/.ddd/init file. These are the settings of DDD 1.x:
Ddd*sourceButtons: \ run\nstep\nnext\nstepi\nnexti\ncont\n\ finish\nkill\nup\ndown\n\ Back\nForward\nEdit\ninterrupt^CThis setting creates some buttons which are not found on the command tool:
Ddd*sourceButtons: \ print *()\ngraph display *()\nprint /x ()\n\ whatis ()\nptype ()\nwatch ()\nuntil\nshellAn even more professional setting uses customized button labels.
Ddd*sourceButtons: \ print *(()) // Print *()\n\ graph display *(()) // Display *()\n\ print /x ()\n\ whatis () // What is ()\n\ ptype ()\n\ watch ()\n\ until\n\ shellSee also the ‘consoleButtons’ and ‘dataButtons’ resources, above, and the ‘toolButtons’ resource, below.
A newline-separated list of buttons to be included in the command tool or the command tool bar (see Disabling the Command Tool). Each button issues the command given by its name. See Defining Buttons, for details on button syntax.
The default resource value is
Ddd*toolButtons: \ run\nbreak^C\nstep\nstepi\nnext\nnexti\n\ until\nfinish\ncont\n\kill\n\ up\ndown\nBack\nForward\nEdit\nMakeFor each button, its location in the command tool must be specified using ‘XmForm’ constraint resources. See the ‘Ddd’ application defaults file for instructions.
If the ‘toolButtons’ resource value is empty, the command tool is not created.
The following resources set up button details:
The string used to separate labels from commands and shortcuts. Default is ‘//’.
If ‘on’ (default), verify for each button whether its command is actually supported by the inferior debugger. If the command is unknown, the button is disabled. If this resource is ‘off’, no checking is done: all commands are accepted “as is”.
Aside from breakpoint commands (see Breakpoint Commands), DDD also allows you to define user-defined commands. A user-defined command is a sequence of commands to which you assign a new name as a command. This new command can be entered at the debugger prompt or invoked via a button.
Aside from breakpoint commands (see ‘Breakpoint commands’, above), DDD also allows you to store sequences of commands as a user-defined GDB command. A user-defined command is a sequence of GDB commands to which you assign a new name as a command. Using DDD, this is done via the Command Editor, invoked via ‘Commands Define Command’.
A GDB command is created in five steps:
After the command is defined, you can enter it at the GDB prompt. You may also click on ‘Execute’ to test the given user-defined command.
For convenience, you can assign a button to the defined command. Enabling one of the ‘Button’ locations will add a button with the given command to the specified location. If you want to edit the button, select ‘Commands Edit Buttons’. See Defining Buttons, for a discussion.
When user-defined GDB commands are executed, the commands of the definition are not printed. An error in any command stops execution of the user-defined command.32
If used interactively, commands that would ask for confirmation proceed without asking when used inside a user-defined command. Many GDB commands that normally print messages to say what they are doing omit the messages when used in a user-defined command.
Command definitions are saved across DDD sessions.
If you want to pass arguments to user-defined commands, you can enable the ‘()’ toggle button in the Command Editor. Enabling ‘()’ has two effects:
While defining a command, you can toggle the ‘()’ button as you wish to switch between using the argument field symbolically and literally.
As an example, let us define a command contuntil that will set a breakpoint in the given argument and continue execution.
There is a little drawback with argument commands: a user-defined command in GDB has no means to access the argument list as a whole; only the first argument (up to whitespace) is processed. This may change in future GDB releases.
If your inferior debugger allows you to define own command sequences, you can also use these user-defined commands within DDD; just enter them at the debugger prompt.
However, you may encounter some problems:
As a solution, DDD provides a simple facility called auto-commands. If DDD receives any output from the inferior debugger in the form ‘prefix command’, it will interpret command as if it had been entered at the debugger prompt. prefix is a user-defined string, for example ‘ddd: ’.
Suppose you want to define a command gd that serves as abbreviation for graph display. All the command gd has to do is to issue a string
ddd: graph display argument
where argument is the argument given to gd. Using GDB, this can be achieved using the echo command. In your ~/.gdbinit file, insert the lines
define gd
echo ddd: graph display $arg0\n
end
To complete the setting, you must also set the ‘autoCommandPrefix’ resource to the ‘ddd: ’ prefix you gave in your command. In ~/.ddd/init, write:
Ddd*autoCommandPrefix: ddd:\
(Be sure to leave a space after the trailing backslash.)
Entering gd foo will now have the same effect as entering graph display foo at the debugger prompt.
Please note: In your commands, you should choose some other prefix than ‘ddd: ’. This is because auto-commands raise a security problem, since arbitrary commands can be executed. Just imagine some malicious program issuing a string like ‘prefix shell rm -fr ~’ when being debugged! As a consequence, be sure to choose your own prefix; it must be at least three characters long.
Like any good X citizen, DDD comes with a large application-defaults file named Ddd. This appendix documents the actions and images referenced in Ddd, such that you can easily modify them.
The following DDD actions may be used in translation tables.
These actions are used in the DDD graph editor.
Extend the current selection. Bound to a button down event. If the pointer is dragged, move the selection.
Equivalent to
select-or-move, but also updates the current argument.
Equivalent to
extend-or-move, but also updates the current argument.
Equivalent to
toggle-or-move, but also updates the current argument.
graph|node|shortcut])Pops up a menu.
graphpops up a menu with global graph operations,nodepops up a menu with node operations, andshortcutpops up a menu with display shortcuts.If no argument is given, pops up a menu depending on the context: when pointing on a node with the <Shift> key pressed, behaves like
shortcut; when pointing on a without the <Shift> key pressed, behaves likenode; otherwise, behaves as ifgraphwas given.
any|both|from|to])Hide some edges.
anymeans to process all edges where either source or target node are selected.bothmeans to process all edges where both nodes are selected.frommeans to process all edges where at least the source node is selected.tomeans to process all edges where at least the target node is selected. Default isany.
regular|compact], [[+|-] degrees])Layout the graph.
regularmeans to use the regular layout algorithm;compactuses an alternate layout algorithm, where successors are placed next to their parents. Default isregular. degrees indicates in which direction the graph should be layouted. Default is the current graph direction.
Move all selected nodes in the direction given by x-offset and y-offset. x-offset and y-offset is either given as a numeric pixel value, or as ‘+grid’, or -grid, meaning the current grid size.
+|-]degrees])Rotate the graph around degrees degrees. degrees must be a multiple of 90. Default is
+90.
Select the node pointed at. Clear all other selections. Bound to a button down event.
Select the node pointed at. Clear all other selections. Bound to a button down event. If the pointer is dragged, move the selected node.
any|both|from|to])Show some edges.
anymeans to process all edges where either source or target node are selected.bothmeans to process all edges where both nodes are selected.frommeans to process all edges where at least the source node is selected.tomeans to process all edges where at least the target node is selected. Default isany.
Toggle the current selection—if the node pointed at is selected, it will be unselected, and vice versa. Bound to a button down event.
Toggle the current selection—if the node pointed at is selected, it will be unselected, and vice versa. Bound to a button down event. If the pointer is dragged, move the selection.
These actions are used in the debugger console and other text fields.
Move cursor to the beginning of the current line, after the prompt. Bound to
HOME.
Send the given control-character to the inferior debugger. control-character must be specified in the form ‘^X’, where X is an upper-case letter, or ‘?’.
Execute command in the debugger console. The following replacements are performed on command:
- If command has the form ‘name...’, insert name, followed by a space, in the debugger console.
- All occurrences of ‘()’ are replaced by the current contents of the argument field ‘()’.
Complete current argument as if command was prepended. Bound to <Ctrl+T>.
Complete current command line in the debugger console. Bound to <TAB>.
If global <TAB> completion is enabled, complete current argument as if command was prepended. Otherwise, proceed as if the <TAB> key was hit. Bound to <TAB>.
Like
gdb-control, but effective only if the cursor is at the end of a line. Otherwise, control-character is ignored and the character following the cursor is deleted. Bound to <Ctrl+D>.
If DDD is in incremental search mode, exit it; otherwise call
gdb-control(^C).
Process the given event in the debugger console. Bound to key events in the source and data window. If this action is bound to the source window, and the source window is editable, perform action
(args...)on the source window instead; if action is not given, perform ‘self-insert()’.
If the ‘selectAllBindings’ resource is set to
Motif, perform ‘beginning-of-line’. Otherwise, perform ‘select-all’. Bound to <Ctrl+A>.
These actions are used in the source and code windows.
The double-click action in the source window.
- If this action is taken on a breakpoint glyph, edit the breakpoint properties.
- If this action is taken in the breakpoint area, invoke ‘gdb-command(line-action)’. If line-action is not given, it defaults to ‘break ()’.
- If this action is taken in the source text, and the next character following the current selection is ‘(’, invoke ‘gdb-command(function-action)’. If function-action is not given, it defaults to ‘list ()’.
- Otherwise, invoke ‘gdb-command(text-action)’. If text-action is not given, it defaults to ‘graph display ()’.
Drop the dragged glyph at cursor position. action is either ‘move’, meaning to move the dragged glyph, or ‘copy’, meaning to copy the dragged glyph. If no action is given, ‘move’ is assumed.
Continue a drag on the glyph at cursor position. Usually bound to some motion event.
Set the argument field to the current selection. Typically bound to some selection operation.
Update all visible glyphs. Usually invoked after a scrolling operation.
DDD installs a number of images that may be used as pixmap resources, simply by giving a symbolic name. For button images, three variants are installed as well:
Sometimes you will encounter a bug in DDD. Although we cannot promise we can or will fix the bug, and we might not even agree that it is a bug, we want to hear about bugs you encounter in case we do want to fix them.
To make it possible for us to fix a bug, you must report it. In order to do so effectively, you must know when and how to do it.
Submit bug reports for DDD at http://savannah.gnu.org/bugs/?group=ddd, the DDD bug tracker. Incoming bug reports are automatically copied to the developers' mailing list bug-ddd@gnu.org.
Before sending in a bug report, try to find out whether the problem cause really lies within DDD. A common cause of problems are incomplete or missing X or M*tif installations, for instance, or bugs in the X server or M*tif itself. Running DDD as
$ ddd --check-configuration
checks for common problems and gives hints on how to repair them.
Another potential cause of problems is the inferior debugger; occasionally, they show bugs, too. To find out whether a bug was caused by the inferior debugger, run DDD as
$ ddd --trace
This shows the interaction between DDD and the inferior debugger on standard error while DDD is running. (If --trace is not given, this interaction is logged in the file ~/.ddd/log; see Logging) Compare the debugger output to the output of DDD and determine which one is wrong.
Here are some guidelines for bug reports:
To enable us to fix a DDD bug, you must include the following information:
$ ddd --configuration
to get the configuration information. If this does not work, please include at least the DDD version, the type of machine you are using, and its operating system name and version number.
Be sure to include this information in every single bug report.
If things go wrong, the first and most important information source is the DDD log file. This file, created in ~/.ddd/log (~ stands for your home directory), records the following information:
This information, all in one place, should give you (and anyone maintaining DDD) a first insight of what's going wrong.
The log files created by DDD can become quite large, so you might want to turn off logging. There is no explicit DDD feature that allows you to do that. However, you can easily create a symbolic link from ~/.ddd/log to ‘/dev/null’, such that logging information is lost. Enter the following commands at the shell prompt:
$ cd
$ rm .ddd/log
$ ln -s /dev/null .ddd/log
$ _
Be aware, though, that having logging turned off makes diagnostics much more difficult; in case of trouble, it may be hard to reproduce the error.
As long as DDD is compiled with -g (see Compiling for Debugging), you can invoke a debugger on DDD—even DDD itself, if you wish. From within DDD, a special ‘Maintenance’ menu is provided that invokes GDB on the running DDD process. See Maintenance Menu, for details.
The DDD distribution comes with a .gdbinit file that is suitable for debugging DDD. Among others, this defines a ‘ddd’ command that sets up an environment for debugging DDD and a ‘string’ command that lets you print the contents of DDD ‘string’ variables; just use ‘print var’ followed by ‘string’.
You can cause DDD to dump core at any time by sending it a
SIGUSR1 signal. DDD resumes execution while you can examine
the core file with GDB.
When debugging DDD, it can be useful to make DDD not catch fatal errors. This can be achieved by setting the environment variable DDD_NO_SIGNAL_HANDLERS before invoking DDD.
You can use these additional resources to obtain diagnostics about DDD. Most of them are tied to a particular invocation option.
The version of the DDD app-defaults file. If this string does not match the version of the current DDD executable, DDD issues a warning.
If ‘on’, check the DDD environment (in particular, the X configuration), report any possible problem causes and exit. See Options, for the --check-configuration option.
The version of the DDD executable that last wrote the ~/.ddd/init file. If this string does not match the version of the current DDD executable, DDD issues a warning.
If ‘on’, DDD invokes a debugger on itself when receiving a fatal signal. See Maintenance Menu, for setting this resource.
If ‘on’ (default), DDD dumps core when receiving a fatal signal. See Maintenance Menu, for setting this resource.
If ‘on’, enables the top-level ‘Maintenance’ menu (see Maintenance Menu) with additional options. See Options, for the --maintenance option.
If ‘on’, show the DDD configuration on standard output and exit. See Options, for the --configuration option.
If ‘on’, show the DDD font definitions on standard output and exit. See Options, for the --fonts option.
If ‘on’, show the DDD invocation options on standard output and exit. See Options, for the --help option.
If ‘on’, show the DDD license on standard output and exit. See Options, for the --license option.
If ‘on’, show this DDD manual page on standard output and exit. If the standard output is a terminal, the manual page is shown in a pager ($PAGER, less or more). See Options, for the --manual option.
If ‘on’, show the DDD news on standard output and exit. See Options, for the --news option.
If ‘on’, show the DDD version on standard output and exit. See Options, for the --version option.
If ‘on’, X warnings are suppressed. This is sometimes useful for executables that were built on a machine with a different X or M*tif configuration. By default, this is ‘off’. See X Warnings, for details.
If ‘on’, show the dialog between DDD and the inferior debugger on standard output. Default is ‘off’. See Options, for the --trace option.
Some GDB settings are essential for DDD to work correctly. These settings with their correct values are:
set height 0
set width 0
set verbose off
set annotate 1
set prompt (gdb)
DDD sets these values automatically when invoking GDB; if these values are changed, there may be some malfunctions, especially in the data display.
When debugging at the machine level with GDB 4.12 and earlier as inferior debugger, use a ‘display /x $pc’ command to ensure the program counter value is updated correctly at each stop. You may also enter the command in ~/.gdbinit or (better yet) upgrade to the most recent GDB version.
HP's WildeBeest (WDB) is essentially a variant of GDB. To start DDD with WDB as inferior debugger, use
ddd --wdb program
See GDB, for further configuration notes.
DDD now supports WindRiver's version of GDB.34 DDD can be integrated into the ‘Launch’ window by placing the launch.tcl script (see below) into the the directory ~/.wind.
Currently, DDD only supports the PowerPC and has been only tested on a Solaris 2.6 host.
DDD launches the version of GDB that is either in the current path, or the one specified on the command line using the ‘--debugger’ command.
Normally, the Tornado environment is set up by sourcing a script file which, among other things, sets up the PATH variable.
It is suggested that a soft link for the version of GDB used for the target (i.e. gdbppc) be made in the same directory:
bin>ls -l gdb*
39 Mar 6 16:14 gdb -> /usr/wind/host/sun4-solaris2/bin/gdbppc*
1619212 Mar 11 1997 gdbppc*
bin>_
This way DDD will start the correct version of GDB automatically.
It is also suggested that you use DDD's execution window to facilitate parsing of GDB output. See Debugger Communication, for details.
Tornado reads the default TCL scripts first, then the ones in the users .wind directory. The following procedures can be cut and pasted into the user's launch.tcl file:
| # Launch.tcl - Launch application Tcl user customization file. # ###### # # setupDDD - sets up DDD for use by the launcher # # This routine adds the DDD to the application bar # # SYNOPSIS: # setupDDD # # PARAMETERS: N/A # # RETURNS: N/A # # ERRORS: N/A # proc setupDDD {} { # Add to the default application bar objectCreate app ddd DDD {launchDDD} } |
| ###### # # launchDDD - launch the DDD debugger # # SYNOPSIS: # launchDDD # # PARAMETERS: N/A # # RETURNS: N/A # # ERRORS: N/A # proc launchDDD {} { global tgtsvr_selected global tgtsvr_cpuid if {$tgtsvr_selected == "" || $tgtsvr_cpuid == 0} { noticePost error "Select an attached target first." return } set startFileName /tmp/dddstartup.[pid] if [catch {open $startFileName w} file] { # couldn't create a startup file. Oh, well. exec ddd --gdb & } else { # write out a little /tmp file that attaches to the # selected target server and then deletes itself. puts $file "set wtx-tool-name ddd" puts $file "target wtx $tgtsvr_selected" puts $file "tcl exec rm $startFileName" close $file exec ddd --gdb --command=$startFileName & } } |
| ###### # # Launch.tcl - Initialization # # The user's resource file sourced from the initial Launch.tcl # # Add DDD to the laucher setupDDD |
In order for DDD to automatically display the source of a previously loaded file, the entry point must be named either ‘vxworks_main’ or ‘main_vxworks’.
See GDB, for further configuration notes.
BASH support is rather new. As a programming language, BASH is not feature rich: there are no record structures or hash tables (yet), no pointers, package variable scoping or methods. So much of the data display and visualization features of DDD are disabled.
As with any scripting or interpreted language like Perl, stepping a machine-language instructions (commands Stepi/Nexti) doesn't exist.
Some BASH settings are essential for DDD to work correctly. These settings with their correct values are:
set annotate 1
set prompt set prompt bashdb$_Dbg_less$_Dbg_greater$_Dbg_space
DDD sets these values automatically when invoking BASH; if these values are changed, there may be some malfunctions.
Pay special attention when the prompt has extra angle brackets (a nested shell) or has any parenthesis (is in a subshell). Quitting may merely exit out of one of these nested (sub)shells rather than leave the program.
When used for debugging Pascal-like programs, DDD does not infer correct array subscripts and always starts to count with 1.
With some DBX versions (notably Solaris DBX), DDD strips C-style and C++-style comments from the DBX output in order to interpret it properly. This also affects the output of the debugged program when sent to the debugger console. Using the separate execution window avoids these problems.
In some DBX versions (notably DEC DBX and AIX DBX), there is no automatic data display. As an alternative, DDD uses the DBX ‘print’ command to access data values. This means that variable names are interpreted according to the current frame; variables outside the current frame cannot be displayed.
All DBX limitations (see DBX) apply to Ladebug as well.
There is no automatic data display in JDB. As a workaround, DDD uses the ‘dump’ command to access data values. This means that variable names are interpreted according to the current frame; variables outside the current frame cannot be displayed.
In JDB 1.1, the ‘dump’ and ‘print’ commands do not support expression evaluation. Hence, you cannot display arbitrary expressions.
Parsing of JDB output is quite CPU-intensive, due to the recognition of asynchronous prompts (any thread may output anything at any time, including prompts). Hence, a program producing much console output is likely to slow down DDD considerably. In such a case, have the program run with -debug in a separate window and attach JDB to it using the -passwd option.
GNU Make support is rather new. As a programming language, GNU Make is a bit of a stretch for DDD. There are no record structures or hash tables, no pointers. Well, actually this does exist, but the records, pointers and hash tables are fixed into the system. There are Makefile variables, “targets” (which sometimes refer to files), dependencies, and commands. There is sort of an “scope” that for variables too.
But much of the data display and visualization features of DDD
are disabled. However info locals does work and you can hover
over a variable and see its value.
As with any scripting or interpreted language like Perl, stepping a machine-language instructions (commands Stepi/Nexti) doesn't exist.
Pay special attention when the prompt has extra angle brackets—nested invocation of GNU MAKE. Quitting may merely exit out of one of these nested invocations rather than leave the program.
There is no automatic data display in Perl. As a workaround, DDD uses the ‘x’ command to access data values. This means that variable names are interpreted according to the current frame; variables outside the current frame cannot be displayed.
In short, make sure you use a newer version of pydb, one from
http://bashdb.sourceforge.net/pydb. Older versions that had
been supplied with DDD will no longer work.
History: Up to around 1999 there was parallel development that went on
between DDD's Python debugger pydb and the stock python debugger
pdb. These were not necessarily competing efforts, just
parallel. In fact the same person worked a little bit on both.
One feature that pydb supported that wasn't in pdb was GDB's
display command.
After 1999, maintaining pydb more or less fell into disuse and pdb
sort of inched ahead with bug fixes and redisigned interaces. Around
the beginning of 2006, new work was started to enhance pdb and to make
it more like GDB. Since DDD already understands a large set of
GDB commands, many of these enhancements were immediately
realizable by DDD. These things include command completion,
restarting the debugger, and using set/show/info commands.
With the blessing of the original author of pydb, the new effort
took over the name of the old one, Although it did not actually start
out from the pydb base but from pdb adding the old pydb
features.
There is no automatic data display in XDB. As a workaround, DDD uses the ‘p’ command to access data values. This means that variable names are interpreted according to the current frame; variables outside the current frame cannot be displayed.
DDD includes a number of hacks that make DDD run with LessTif, a free M*tif library without loss of functionality. Since a DDD binary may be dynamically bound and used with either an OSF/Motif or LessTif library, these lesstif hacks can be enabled and disabled at run time.
Whether the lesstif hacks are included at run-time depends on the setting of the ‘lessTifVersion’ resource:
Indicates the LessTif version DDD is running against. For LessTif version x.y, the value is x multiplied by 1000 plus y—for instance, the value
79stands for LessTif 0.79 and the value1005stands for LessTif 1.5.If the value of this resource is less than 1000, indicating LessTif 0.99 or earlier, DDD enables version-specific hacks to make DDD work around LessTif bugs and deficiencies.
If DDD was compiled against LessTif, the default value is the value of the ‘LessTifVersion’ macro in <Xm/Xm.h>. If DDD was compiled against OSF/Motif, the default value is
1000, disabling all LessTif-specific hacks.
To set the ‘lessTifVersion’ resource at DDD invocation and to specify the version number of the LessTif library, you can also use the option --lesstif-version version.
The default value of the ‘lessTifVersion’ resource is derived from
the LessTif library DDD was compiled against (or 1000
when compiled against OSF/Motif). Hence, you normally don't need to
worry about the value of this resource. However, if you use a
dynamically linked DDD binary with a library other than the one
DDD was compiled against, you must specify the version number of
the library using this resource. (Unfortunately, DDD cannot
detect this at run-time.)
Here are a few scenarios to illustrate this scheme:
To find out the LessTif or OSF/Motif version DDD was compiled against, invoke DDD with the --configuration option.
In the DDD source, LessTif-specific hacks are controlled by the string ‘lesstif_version’.
Do you miss anything in this manual? Do you have any material that should be added? Please send any contributions to ddd@gnu.org.
If you have any contributions to be incorporated into DDD, please send them to ddd@gnu.org. For suggestions on what might be done, see the file ‘TODO’ in the DDD distribution.
See the DDD WWW page for frequently answered questions not covered in this manual.
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(): GDB Argument Commands3-D Lines: Plot AppearanceAbort: Program MenuAbort: QuittingAbout DDD: Help MenuAlign on Grid: Data MenuAll Signals: SignalsApply: Commands MenuAttach: Attaching to a ProcessAttach to Process: Attaching to a ProcessAttach to Process: File MenuAuto-align Displays on Nearest Grid Point: Aligning DisplaysAutomatic Display of Button Hints: Button tipsAutomatic Display of Variable Values: Value TipsBacktrace: Status MenuBash Console: View MenuBash Reference: Getting HelpBash Reference: Help MenuBreak: Setting BreakpointsBreak: Tool BarBreakpoints: Source MenuButton: GDB Simple CommandsCache Machine Code: Customizing Machine CodeCache source files: Customizing Source LookupChange Directory: Working DirectoryChange Directory: File MenuClear: Disabling BreakpointsClear: Deleting BreakpointsClear: Tool BarClear: Edit MenuClear Line: Commands MenuClear Undo Buffer: Customizing UndoClear Window: Commands MenuClose: File MenuClose data window when deleting last display: Deleting DisplaysCluster: ClusteringCluster Data Displays: Clusteringclustered: ClusteringColor: Printing the GraphCommand: GDB Simple CommandsCommand: Entering Plotting CommandsCommand History: Commands MenuCommand Tool: View MenuCommands: Commands MenuCommands: Menu BarComplete: Commands MenuCont: Command ToolContinue: Continuing Somewhere ElseContinue: Resuming ExecutionContinue: Program MenuContinue Automatically when Mouse Pointer is Frozen: Stopping X ProgramsContinue Until Here: Temporary BreakpointsContinue Without Signal: SignalsContinue Without Signal: Program MenuContour: Plot AppearanceCopy: Deleting DisplaysCopy: Edit MenuCtrl+A is: Customizing the Edit MenuCtrl+C is: Customizing the Edit MenuCut: Deleting DisplaysCut: Edit MenuData: Data MenuData: Menu BarData Scrolling: Scrolling DataData Window: View MenuDBX Console: View MenuDBX Reference: Getting HelpDBX Reference: Help MenuDBX Settings: Edit MenuDDD License: Help MenuDDD News: Help MenuDDD Reference: Getting HelpDDD Reference: Help MenuDDD Splash Screen: Splash ScreenDDD WWW Page: Getting HelpDDD WWW Page: Help MenuDebug DDD: Maintenance MenuDebugger Reference: Getting HelpDebugger Reference: Help MenuDebugger Settings: Edit MenuDebugger Type: Debugger InvocationDefine Command: Commands MenuDelete: Editing Breakpoint PropertiesDelete: Deleting BreakpointsDelete: Edit MenuDelete: Deleting SessionsDelete Breakpoint: Deleting BreakpointsDetach Process: Attaching to a ProcessDetach Process: File MenuDetect Aliases: Shared StructuresDetect Aliases: Data MenuDetermine Automatically from Arguments: Debugger InvocationDisable: Editing Breakpoint PropertiesDisable: Disabling BreakpointsDisable Breakpoint: Disabling BreakpointsDisp *: Dereferencing PointersDisplay: Creating Single DisplaysDisplay: Display BasicsDisplay: Tool BarDisplay (): Data MenuDisplay *: Dereferencing PointersDisplay *(): Dereferencing PointersDisplay Arguments: Displaying Local VariablesDisplay Arguments: Data MenuDisplay Line Numbers: Source MenuDisplay Local Variables: Displaying Local VariablesDisplay Local Variables: Data MenuDisplay Machine Code: Source MenuDisplay Source Line Numbers: Customizing Source AppearanceDisplay Two-Dimensional Arrays as Tables: Arrays as TablesDisplays: Data MenuDo Nothing: Maintenance MenuDown: Selecting a frameDown: Command ToolDown: Status MenuDump Core: Maintenance MenuDump Core Now: Maintenance MenuEdit: Editing Source CodeEdit: Command ToolEdit: Edit MenuEdit: Menu BarEdit <<: GDB Simple CommandsEdit >>: GDB Simple CommandsEdit >>: Breakpoint CommandsEdit Buttons: Defining ButtonsEdit Buttons: Commands MenuEdit Menu: Display ShortcutsEdit Source: Editing Source CodeEdit Source: Source MenuEdit Sources: Editing Source CodeEdit Themes: Editing ThemesEnable: Editing Breakpoint PropertiesEnable: Disabling BreakpointsEnable Breakpoint: Disabling BreakpointsEnable supported buttons only: Defining ButtonsEnd: GDB Simple CommandsEnd: Breakpoint CommandsExecute: GDB Simple CommandsExecution Window: Customizing the Execution WindowExecution Window: View MenuExit: File MenuExit: QuittingFile: File MenuFile: Menu BarFile Name: Printing the GraphFind <<: Textual SearchFind << (): Source MenuFind >>: Textual SearchFind >>: Tool BarFind >> (): Source MenuFind Backward: Commands MenuFind Case Sensitive: Source MenuFind Forward: Commands MenuFind Words Only: Textual SearchFind Words Only: Source MenuFinish: Resuming ExecutionFinish: Command ToolFinish: Program MenuGDB Console: View MenuGDB Reference: Getting HelpGDB Reference: Help MenuGDB Settings: Edit MenuGet Core File: Customizing SessionsGNU Make Console: View MenuGreen background: Using Data ThemesHelp: Getting HelpHelp: Help MenuHelp: Menu BarHide: Showing and Hiding DetailsHide: Tool BarIconify all windows at once: IconsIgnore Count: Breakpoint Ignore CountsInclude Core Dump: Saving SessionsIntel x86 flab gits and registers: Using Data ThemesInterrupt: InterruptingInterrupt: Command ToolInterrupt: Program MenuJDB Console: View MenuJDB Reference: Getting HelpJDB Reference: Help MenuJDB Settings: Edit MenuKill: Killing the ProgramKill: Command ToolKill: Program MenuLadebug Console: View MenuLadebug Reference: Getting HelpLadebug Reference: Help MenuLadebug Settings: Edit MenuLandscape: Printing PlotsLayout Graph: Automatic LayoutLayout Graph: Data MenuLeft to right: PlacementList Processes: Attaching to a ProcessLookup: Editing Breakpoint PropertiesLookup: Looking up DefinitionsLookup: Tool BarLookup (): Source MenuMachine Code Indentation: Customizing Machine CodeMachine Code Window: View MenuMaintenance: Maintenance MenuMaintenance: Menu BarMake: RecompilingMake: Command ToolMake: File MenuMemory: Examining MemoryMemory: Data MenuNew Display: Display ShortcutsNew Game: Maintenance MenuNext: Resuming ExecutionNext: Command ToolNext: Commands MenuNext: Program MenuNext Instruction: Machine Code ExecutionNext Instruction: Program MenuNexti: Machine Code ExecutionNexti: Command ToolOn item: Help MenuOpen: Opening Source FilesOpen: Opening Core DumpsOpen: Opening ProgramsOpen Class: Opening ProgramsOpen Class: File MenuOpen Core Dump: File MenuOpen Program: Attaching to a ProcessOpen Program: Opening ProgramsOpen Program: File MenuOpen Recent: Opening ProgramsOpen Recent: File MenuOpen Session: File MenuOpen Session: Resuming SessionsOpen Source: Opening Source FilesOpen Source: File MenuOrientation: Printing the GraphOther: Display ShortcutsOverview: Help MenuPaper Size: Printing PlotsPaper Size: Printing the GraphPass: SignalsPaste: Deleting DisplaysPaste: Edit MenuPerl Console: View MenuPerl Reference: Getting HelpPerl Reference: Help MenuPerl Settings: Edit MenuPlacement: ClusteringPlacement: PlacementPlot: Gnuplot InvocationPlot: Plot AppearancePlot: Tool BarPlot Window: Gnuplot InvocationPortrait: Printing PlotsPreferences: Edit MenuPrevious: Commands MenuPrint: Printing ValuesPrint: SignalsPrint: Editing all WatchpointsPrint: Editing Watchpoint PropertiesPrint: Tool BarPrint (): Data MenuPrint Command: Printing the GraphPrint Graph: Printing the GraphPrint Graph: File MenuPrint Plot: Printing PlotsProgram: Program MenuProgram: Menu BarPYDB Console: View MenuPYDB Reference: Getting HelpPYDB Reference: Help MenuPYDB Settings: Edit MenuQuit Search: Commands MenuRecord: GDB Simple CommandsRecord: Breakpoint CommandsRed Background: Applying Data Themes to Several ValuesRed Background: Using Data ThemesRedo: Undoing Program ExecutionRedo: Looking up Previous LocationsRedo: Undo and RedoRedo: Command ToolRedo: Edit MenuRefer to Program Sources: Customizing Source LookupRefresh: Data MenuRefresh Displays: Repeated ValuesRefresh Displays: Refreshing the Data WindowRegisters: RegistersRegisters: Status MenuReload Source: Editing Source CodeReload Source: Source MenuRemove Menu: Maintenance MenuReset: SignalsRestart: File MenuRotate: Tool BarRotate Graph: Rotating the GraphRotate Graph: Data MenuRun: Starting Program ExecutionRun: Command ToolRun: Program MenuRun Again: Starting Program ExecutionRun Again: Program MenuRun in Execution Window: Using the Execution WindowRun in Execution Window: Program MenuSave Data As: Exporting Plot DataSave Options: SignalsSave Options: Edit MenuSave Session As: SignalsSave Session As: File MenuSave Session As: Saving SessionsScale: Plot AppearanceSearch path for source files: Source PathSelect All: Edit MenuSelected Only: Printing PlotsSelected Only: Printing the GraphSend: SignalsSet: AssignmentSet: Tool BarSet Execution Position: Continuing Somewhere ElseSet Temporary Breakpoint: Temporary BreakpointsSet Value: AssignmentShow: Showing and Hiding DetailsShow: Tool BarShow All: Showing and Hiding DetailsShow Just: Showing and Hiding DetailsShow More: Showing and Hiding DetailsShow Position and Breakpoints: Customizing GlyphsSignals: SignalsSignals: Status MenuSmall Titles: Using Data ThemesSmall Values: Using Data ThemesSource: Source MenuSource: Menu BarSource indentation: Customizing Source AppearanceSource Window: View MenuStatus: Status MenuStatus: Menu BarStatus Displays: Displaying Program StatusStatus Displays: Data MenuStep: Resuming ExecutionStep: Command ToolStep: Program MenuStep Instruction: Machine Code ExecutionStep Instruction: Program MenuStepi: Machine Code ExecutionStepi: Command ToolStop: SignalsSuppress Values: Using Data ThemesSuppress Values: Deleting DisplaysSuppress X warnings: X WarningsTab Width: Customizing Source AppearanceTemp: Editing Breakpoint PropertiesTheme: Using Data ThemesThemes: Editing ThemesThreads: ThreadsThreads: Status MenuThreshold for repeated print elements: Repeated ValuesTic Tac Toe: Maintenance MenuTiny Values: Using Data ThemesTip of the Day: Help MenuTool Bar Appearance: Window LayoutTool Buttons Location: Disabling the Command ToolTop to bottom: PlacementUncluster: ClusteringUncompress: Help HelpersUndisp: Deleting DisplaysUndisp: Tool BarUndisplay: Display BasicsUndo: Deleting DisplaysUndo: Showing and Hiding DetailsUndo: Undoing Program ExecutionUndo: Selecting a frameUndo: Looking up Previous LocationsUndo: Undo and RedoUndo: Command ToolUndo: Edit MenuUndo Buffer Size: Customizing UndoUniconify When Ready: Program StopUntil: Resuming ExecutionUntil: Command ToolUntil: Program MenuUnwatch: Tool BarUp: Selecting a frameUp: Command ToolUp: Status MenuView: Plot AppearanceView: View MenuView: Menu BarWarn if Multiple DDD Instances are Running: Multiple InstancesWatch: Editing Watchpoint PropertiesWatch: Setting WatchpointsWatch: Tool BarWatchpoints: Data MenuWeb Browser: Help HelpersWhat Now?: Getting HelpWhat Now?: Help MenuWhen DDD Crashes: Maintenance MenuWindow Layout: Window LayoutWriting into executable and core files: PatchingXDB Console: View MenuXDB Reference: Getting HelpXDB Reference: Help MenuXDB Settings: Edit MenuAlt+1: View MenuAlt+2: View MenuAlt+3: View MenuAlt+4: Source MenuAlt+4: View MenuAlt+8: View MenuAlt+9: View MenuAlt+A: Data MenuAlt+G: Data MenuAlt+I: Source MenuAlt+L: Data MenuAlt+N: Source MenuAlt+R: Data MenuAlt+U: Data MenuAlt+W: Source MenuAlt+Y: Data MenuCtrl+,: Source MenuCtrl+-: Data MenuCtrl+.: Source MenuCtrl+/: Source MenuCtrl+=: Data MenuCtrl+\: Program MenuCtrl+\: QuittingCtrl+A: Edit MenuCtrl+B: Command HistoryCtrl+B: Commands MenuCtrl+C: InterruptingCtrl+C: Customizing the Edit MenuCtrl+C: Program MenuCtrl+C: Edit MenuCtrl+C: QuittingCtrl+D: QuittingCtrl+Down: Selecting a frameCtrl+Down: Status MenuCtrl+F: Command HistoryCtrl+F: Commands MenuCtrl+F1: Getting HelpCtrl+Ins: Edit MenuCtrl+L: Data MenuCtrl+M: File MenuCtrl+N: File MenuCtrl+O: File MenuCtrl+Q: File MenuCtrl+Q: QuittingCtrl+Q: InvocationCtrl+S: File MenuCtrl+Shift+A: Customizing the Edit MenuCtrl+Shift+A: Edit MenuCtrl+U: Commands MenuCtrl+U: Edit MenuCtrl+Up: Selecting a frameCtrl+Up: Status MenuCtrl+V: Edit MenuCtrl+W: File MenuCtrl+X: Edit MenuCtrl+Y: Edit MenuCtrl+Z: Edit MenuDown: Command HistoryDown: Moving DisplaysDown: Selecting DisplaysDown: Commands MenuESC: Command HistoryESC: InterruptingESC: Customizing the Edit MenuEsc: Commands MenuEsc: Program MenuESC: QuittingF1: Getting HelpF12: Maintenance MenuF2: Program MenuF3: Program MenuF4: Program MenuF5: Program MenuF6: Program MenuF7: Program MenuF8: Program MenuF9: Program MenuHome: Customizing the Edit MenuLeft: Moving DisplaysLeft: Selecting DisplaysReturn: Command HistoryReturn: Commands MenuRight: Moving DisplaysRight: Selecting DisplaysShift: Selecting DisplaysShift+Ctrl+L: Source MenuShift+Ctrl+U: Commands MenuShift+Ctrl+V: Source MenuShift+Del: Edit MenuShift+F5: Program MenuShift+F6: Program MenuShift+F9: Program MenuShift+Ins: Edit MenuTAB: Tool BarTab: Commands MenuUp: Command HistoryUp: Moving DisplaysUp: Selecting DisplaysUp: Commands Menucont: Undoing Program Executioncont: Customizing Grab Checkingcontuntil: GDB Argument Commandsdirectory: Source Pathdown: Selecting a framefile: Remote Programgcore: Customizing Sessionsgd: Commands with Other Debuggersgraph apply theme: Applying Data Themes to Several Valuesgraph disable display: Showing and Hiding Detailsgraph display: Displaying Program Statusgraph display: Creating Single Displaysgraph enable display: Showing and Hiding Detailsgraph plot: Plotting Arraysgraph refresh: Refreshing the Data Windowgraph toggle theme: Applying Data Themes to Several Valuesgraph unapply theme: Applying Data Themes to Several Valuesgunzip: Help Helpersgzip: Help Helpershbreak: Hardware-Assisted Breakpointshelp: Getting Helpkill: Customizing Grab Checkingmwm: Gnuplot Invocationprint: Printing Valuesquit: Customizing Grab Checkingquit: Quittingremsh: Remote Debuggerreplot: Entering Plotting Commandsrsh: Remote Debuggerrun: Starting Program Executionset environment: Environmentset output: Entering Plotting Commandsset term: Entering Plotting Commandstarget remote: Remote Programthbreak: Hardware-Assisted Breakpointstty: Debugger Communicationunset environment: Environmentup: Selecting a framezcat: Help HelpersactiveButtonColorKey: Customizing the Tool Baralign2dArrays: Arrays as TablesappDefaultsVersion: Customizing DiagnosticsarrayOrientation: Rotating DisplaysautoCloseDataWindow: Display ResourcesautoDebugger: Debugger InvocationautoRaiseMenu: Auto-Raise MenusautoRaiseMenuDelay: Auto-Raise MenusautoRaiseTool: Customizing Tool Positionbash: GNU Make Initializationbash: Bash InitializationbashDisplayShortcuts: Display ShortcutsbashInitCommands: Bash InitializationblockTTYInput: Debugger Communicationbreak_at: ImagesbufferGDBOutput: Debugger CommunicationbumpDisplays: Display ResourcesbuttonCaptionGeometry: Customizing the Tool BarbuttonCaptions: Customizing the Tool BarbuttonColorKey: Customizing the Tool BarbuttonDocs: Button tipsbuttonImageGeometry: Customizing the Tool BarbuttonImages: Customizing the Tool BarbuttonTips: Button tipscacheGlyphImages: Customizing GlyphscacheMachineCode: Customizing Machine CodecacheSourceFiles: Customizing Source LookupcheckConfiguration: Customizing DiagnosticscheckGrabDelay: Customizing Grab CheckingcheckGrabs: Customizing Grab CheckingcheckOptions: Multiple InstancesCLASSPATH: Source Pathclear_at: ImagesclusterDisplays: Display ResourcescommandToolBar: Disabling the Command ToolcommonToolBar: Window LayoutconsoleButtons: Customizing ButtonsconsoleHasFocus: Typing in the Source WindowcontInterruptDelay: Debugger CommunicationcutCopyPasteBindings: Customizing the Edit MenudataButtons: Customizing ButtonsdataFont: Customizing FontsdataFontSize: Customizing FontsdbxDisplayShortcuts: Display ShortcutsdbxInitCommands: DBX InitializationdbxSettings: DBX Initializationddd: ImagesDDD: EnvironmentDDD_NO_SIGNAL_HANDLERS: Debugging <acronym>DDD</acronym>DDD_SESSION: ResourcesDDD_SESSIONS: Customizing SessionsDDD_STATE: ResourcesdddinitVersion: Customizing DiagnosticsdebugCoreDumps: Customizing Diagnosticsdebugger: Debugger InvocationdebuggerCommand: Debugger InvocationdecorateTool: Customizing Tool DecorationdefaultFont: Customizing FontsdefaultFontSize: Customizing Fontsdelete: ImagesdeleteAliasDisplays: Shared StructuresdetectAliases: Shared Structuresdisable: Imagesdisassemble: Customizing Machine Codedisplay: ImagesDISPLAY: Remote HostDISPLAY: X OptionsdisplayGlyphs: Customizing GlyphsdisplayLineNumbers: Customizing Source AppearancedisplayPlacement: PlacementdisplayTimeout: Debugger Communicationdispref: Imagesdrag_arrow: Imagesdrag_cond: Imagesdrag_stop: Imagesdrag_temp: ImagesdumpCore: Customizing DiagnosticseditCommand: Customizing EditingEDITOR: Customizing Editingenable: ImagesexpandRepeatedValues: Repeated ValuesfilterFiles: Customizing File Filteringfind_backward: Imagesfind_forward: ImagesfindCaseSensitive: Customizing SearchingfindWordsOnly: Customizing SearchingfixedWidthFont: Customizing FontsfixedWidthFontSize: Customizing FontsflatDialogButtons: Customizing the Tool BarflatToolbarButtons: Customizing the Tool BarfontSelectCommand: Customizing FontsgdbDisplayShortcuts: Display ShortcutsgdbInitCommands: GDB InitializationgdbSettings: GDB InitializationgetCoreCommand: Customizing SessionsglobalTabCompletion: Command CompletionglyphUpdateDelay: Customizing GlyphsgrabAction: Customizing Grab CheckinggrabActionDelay: Customizing Grab Checkinggrey_arrow: Imagesgrey_cond: Imagesgrey_stop: Imagesgrey_temp: ImagesgroupIconify: Iconshide: ImageshideInactiveDisplays: Display ResourcesindentCode: Customizing Machine CodeindentScript: Customizing Source AppearanceindentSource: Customizing Source AppearanceinitSymbols: Finding a Place to StartjdbDisplayShortcuts: Display ShortcutsjdbInitCommands: JDB InitializationjdbSettings: JDB InitializationlabelDelimiter: Customizing ButtonslessTifVersion: LessTiflineBufferedConsole: Input/OutputlineNumberWidth: Customizing Source AppearancelinesAboveCursor: Customizing Source ScrollinglinesBelowCursor: Customizing Source ScrollinglistCoreCommand: Customizing Remote DebugginglistDirCommand: Customizing Remote DebugginglistExecCommand: Customizing Remote DebugginglistSourceCommand: Customizing Remote Debugginglookup: Imagesmaintenance: Customizing DiagnosticsmakeInitCommands: GNU Make Initializationmaketemp: ImagesmaxDisassemble: Customizing Machine CodemaxGlyphs: Customizing GlyphsmaxUndoDepth: Customizing UndomaxUndoSize: Customizing Undonew_break: Imagesnew_display: Imagesnew_watch: ImagesopenDataWindow: Toggling WindowsopenDebuggerConsole: Toggling WindowsopenSelection: Opening the SelectionopenSourceWindow: Toggling WindowsPAGER: Customizing DiagnosticsPAGER: EnvironmentpannedGraphEditor: Scrolling DatapaperSize: Printing the GraphperlDisplayShortcuts: Display ShortcutsperlInitCommands: Perl InitializationperlSettings: Perl Initializationplain_arrow: Imagesplain_cond: Imagesplain_stop: Imagesplain_temp: Imagesplot2dSettings: Gnuplot Settingsplot3dSettings: Gnuplot SettingsplotCommand: Gnuplot InvocationplotInitCommands: Gnuplot SettingsplotTermType: Gnuplot InvocationplotWindowClass: Gnuplot InvocationplotWindowDelay: Gnuplot InvocationpopdownHistorySize: Text FieldspositionTimeout: Debugger Communicationprint: ImagesprintCommand: Printing the Graphproperties: ImagespsCommand: Customizing Attaching to ProcessespydbDisplayShortcuts: Display ShortcutspydbInitCommands: PYDB InitializationpydbSettings: PYDB InitializationquestionTimeout: Debugger Communicationrotate: ImagesrshCommand: Customizing Remote DebuggingrunInterruptDelay: Debugger CommunicationsaveHistoryOnExit: Command HistorysaveOptionsOnExit: Saving OptionsselectAllBindings: Customizing the Edit MenuseparateDataWindow: Window LayoutseparateExecWindow: Customizing the Execution WindowseparateSourceWindow: Window Layoutset: ImagesSHELL: Argumentsshow: ImagesshowBaseDisplayTitles: Display ResourcesshowConfiguration: Customizing DiagnosticsshowDependentDisplayTitles: Display ResourcesshowFonts: Customizing DiagnosticsshowInvocation: Customizing DiagnosticsshowLicense: Customizing DiagnosticsshowManual: Customizing DiagnosticsshowMemberNames: Rotating DisplaysshowNews: Customizing DiagnosticsshowVersion: Customizing Diagnosticssignal_arrow: ImagessortPopdownHistory: Text FieldssourceButtons: Customizing ButtonssourceEditing: In-Place EditingsourceInitCommands: GDB InitializationsplashScreen: Splash ScreensplashScreenColorKey: Splash ScreenstartupTipCount: Tip of the daystartupTips: Tip of the daystatusAtBottom: Window LayoutstickyTool: Customizing Tool PositionstopAndContinue: Debugger CommunicationstructOrientation: Rotating DisplayssuppressTheme: Display ResourcessuppressWarnings: Customizing DiagnosticssuppressWarnings: X WarningssynchronousDebugger: Debugger CommunicationtabWidth: Customizing Source AppearanceTERM: Customizing the Execution WindowTERM: EnvironmentTERMCAP: EnvironmenttermCommand: Customizing the Execution WindowterminateOnEOF: Debugger CommunicationtermType: Customizing the Execution Windowthemes: Display Resourcestip: Tip of the daytoolbarsAtBottom: Window LayouttoolButtons: Customizing ButtonstoolRightOffset: Customizing Tool PositiontoolTopOffset: Customizing Tool Positiontrace: Customizing DiagnosticstypedAliases: Shared StructuresuncompressCommand: Help Helpersundisplay: ImagesuniconifyWhenReady: Iconsunwatch: ImagesuseSourcePath: Customizing Source LookupuseTTYCommand: Debugger CommunicationvalueDocs: Value TipsvalueTips: Value TipsvariableWidthFont: Customizing FontsvariableWidthFontSize: Customizing FontsverifyButtons: Customizing ButtonsvslBaseDefs: VSL ResourcesvslDefs: VSL ResourcesvslLibrary: VSL ResourcesvslPath: VSL ResourceswarnIfLocked: Multiple Instanceswatch: ImagesWWWBROWSER: Help HelperswwwCommand: Help HelperswwwPage: Help HelpersxdbDisplayShortcuts: Display ShortcutsxdbInitCommands: XDB InitializationxdbSettings: XDB InitializationXEDITOR: Customizing Editing.emacs: Integrating <acronym>DDD</acronym>.gdbinit: Debugging <acronym>DDD</acronym>.gdbinit: Remote Program.gdbinit: GDB OptionsChangeLog: Contributorsdbx: OptionsDdd: Application DefaultsDdd: More CustomizationsDdd: Resourcesddd-3.3.12-html-manual.tar.gz: About this Manualddd-3.3.12-pics.tar.gz: About this Manualddd-3.3.12.tar.gz: About this Manualddd-version-html-manual.tar.gz: Getting <acronym>DDD</acronym>ddd-version-pics.tar.gz: Getting <acronym>DDD</acronym>ddd-version.tar.gz: Getting <acronym>DDD</acronym>emacs: Integrating <acronym>DDD</acronym>emacs: Customizing Editingemacs: Help Helpersemacsclient: Customizing Editingemacsserver: Customizing Editingfig2dev: Printing the Graphfile: Customizing Remote Debuggingfirefox: Help Helpersgdb: Optionsgdbserver: Remote Programgnuclient: Customizing Editinggnudoit: Help Helpersgnuplot: Plot Appearancegnuserv: Customizing Editinginit: Resourcesjava.prof: JDB Optionsjdb: Optionsladebug: Optionsless: Customizing Diagnosticslog: Logginglog: Entering Plotting Commandslog: Optionslynx: Help Helpersmake: Recompilingmdb: Optionsmore: Customizing Diagnosticsmozilla: Help Helpersnetscape: Help Helperson: Customizing Remote Debuggingperl: Optionsps: Customizing Attaching to Processespydb: Optionsremsh: Customizing Remote Debuggingrsh: Customizing Remote Debuggingsample: Sample Sessionsample.c: Sample Programsample.c: Sample Sessionsessions: Customizing Sessionsssh: Customizing Remote Debuggingstty: Input/Outputsuppress.vsl: Display ResourcesTODO: Contributorstransfig: Printing the Graphvi: Customizing Editingwdb: Optionsxdb: Optionsxemacs: Integrating <acronym>DDD</acronym>xemacs: Customizing Editingxemacs: Help Helpersxfig: Printing the Graphxfontsel: Customizing Fontsxmgr: Exporting Plot Dataxsm: Resuming Sessionsxterm: Customizing the Execution Windowxxgdb: Integrating <acronym>DDD</acronym>~: Resources~: Options[1] Within DDD (and this manual), Ladebug is considered a DBX variant. Hence, everything said for DBX also applies to Ladebug, unless stated otherwise.
[2] XDB will no longer be maintained in future DDD releases. Use a recent GDB version instead.
[3] Actual numbers and behavior on your system may vary.
[4] Re-invoke DDD with --gdb, if you do not see a ‘(gdb)’ prompt here (see Choosing an Inferior Debugger)
[5] Only if a core file is included.
[6] If a core file is not to be included in the session, DDD data displays are saved as deferred; that is, they will be restored as soon as program execution reaches the scope in which they were created. See Creating Single Displays, for details.
[7] Requires X11R6 or later.
[8] If you use a Ddd application-defaults file, you will not be able to maintain multiple DDD versions at the same time. This is why the suiting Ddd is normally compiled into the DDD executable.
[9] If you use DDD to debug Perl, Python or Bash scripts, then this section does not apply.
[10] With XDB and some DBX variants, the debugged program must be specified upon invocation and cannot be changed at run time.
[11] JDB,
pydb, Perl, and Bash do not support core dumps.
[12] JDB does not support breakpoint disabling.
[13] JDB does not support temporary breakpoints.
[14] GDB has no way to make a temporary breakpoint non-temporary again.
[15] JDB, Perl and some DBX variants do not support breakpoint ignore counts.
[16] JDB, pydb, and some DBX variants do
not support breakpoint commands.
[17] When glyphs are disabled (see Customizing Source), breakpoints cannot be dragged. Delete and set breakpoints instead.
[18] Watchpoints are available in GDB and some DBX variants only. In XDB, a similar feature is available via XDB assertions; see the XDB documentation for details.
[19] If <Ctrl+C> is not bound to ‘Copy’ (see Customizing the Edit Menu), you can also use <Ctrl+C> to interrupt the running program.
[20] If the debuggee runs in a separate execution window, the debuggee's TERM value is set according to the ‘termType’ resource; See Customizing the Execution Window, for details.
[21] The execution window is not available in JDB.
[22] JDB, pydb, Perl, and Bash do not support
attaching the debugger to running processes.
[23] JDB, pydb, Perl, and Bash do not support
altering the execution position.
[24] When glyphs are disabled (see Customizing Source), dragging the execution position is not possible. Set the execution position explicitly instead.
[25] Perl does not allow changing the current stack frame.
[26] Currently, threads are supported in GDB and JDB only.
[27] This requires that the full array size is known to the debugger.
[28] JDB 1.1 does not support changing variable values.
[29] The string ‘//’; can be changed via the ‘labelDelimiter’ resource. See Customizing Buttons, for details.
[30] The machine code window is available with GDB and some DBX variants only.
[31] The machine code window is available with GDB and some DBX variants only.
[32] If you use DDD commands within command definitions, or if you include debugger commands that resume execution, these commands will be realized transparently as auto-commands—that is, they won't be executed directly by the inferior debugger, but result in a command string being sent to DDD. This command string is then interpreted by DDD and sent back to the inferior debugger, possibly prefixed by some other commands such that DDD can update its state. See Commands with Other Debuggers, for a discussion.
[33] Since the inferior debugger is invoked through a virtual TTY, standard error is normally redirected to standard output, so DDD never receives standard error from the inferior debugger.
[34] This section was contributed by Gary Cliff from Computing Devices Canada Ltd., gary.cliff@cdott.com.