I've found this question, but even when is close to what I need, is useless
Basically, I have an app that needs to do something when another process (of known name) is launched and/or terminated, but i don't have the PID, so i can't set a kqueue to look for it.
I could do a while for "ps aux | grep processtolook | grep -v grep" command, but that's my last resort.
Any ideas?
Look at this answer: Determine Process Info Programmatically in Darwin/OSX. The libproc.h header file has proc_listpids which will get you all the pids. You can then get the pid information in a loop and using proc_pidinfo and check the name. Looking at the top source as suggested there might also be worthwhile. (The current verson is here http://www.opensource.apple.com/source/top/top-67/.)
Unfortunately, this is an undocumented interface and subject to change at any time. Also, it isn't the quickest thing, since you have to loop over all the processes in the system. In general, this isn't a great way to do this.
A better way might be to write a new processtolook that simply invoked the old one which you can move or rename. It could then notify you of the process start and stop. Is that a possibility?