I have been debugging the fb_inet_server trying to find a problem in Firebird 2.1.2 Classic for PowerPC. That takes a little bit of setting up, but I will try and explain that in another blog post. Part of one of the things that I wanted to check was what malloc was doing. However by default any "error" messages get sent to standard out, however you can set the environment variable MallocLogFile to capture messages to a specified file. But setting that in my normal environment is going to work because the fb_inet_server is actually launched by the LaunchDaemon and is then also forked. So we need to set the environment variable in the LaunchDaemon script directly.
You need to edit the xml script that "launches" the fb_inet_server. This file can be found in /Library/LaunchDaemons and is called org.firebird.gds.plist
First of all unload the current launch definition
launchctl unload /Library/LaunchDaemons/org.firebird.gds.plist
Then edit the file as follows
launchctl load /Library/LaunchDaemons/org.firebird.gds.plist