If you configure apcupsd to run with pthreads (--with-pthreads on the ./configure line), apcupsd will run considerably faster, otherwise said, it will consume less of your CPU, and it will use approximately one third of the memory. For example, Carl Erhorn reports that on his Solaris system, "With the old 3-process version, we averaged about 4.8MB of total memory used. With the new single process, we use only about 1.7MB! That's also a very good improvement."
On master machines, we modify /etc/rc.d/init.d/halt to re-invoke apcupsd with the --killpower option (actually the script apccontrol is called). This causes the UPS to send the codes to the UPS to make it power off.
On slave machines, these modifications should not be made to the /etc/rc.d/init.d/halt script since the slave has no connection to the UPS.
To eliminate the problem, on all your slave machines, either restore the original halt file, or simply delete all the lines containing ***apcupsd***, which were inserted by the apcupsd installation process.
man MAKEDEV
or
find / -name MAKEDEV it is often located in /dev/MAKEDEV