Observe a Process of Unknown PID (no UI)

Question

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?

do you know the name of the process/program of which you want the pid? — phoxis, May 18 '11 at 14:03
Generic process or an Application? If an app, see NSRunningApplication — bbum, May 18 '11 at 15:10

score 2 · Accepted Answer · edited May 23 '17 at 12:19

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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?

edited May 23 '17 at 12:19

Community

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answered May 18 '11 at 14:30

andrewdski

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+1 for last paragraph. That's the real solution: replacing the program to be watched with a wrapper that notifies your program. – R.. GitHub STOP HELPING ICE May 18 '11 at 14:38
No, is not a posibility since is a System invoked process (is invoked by OSX when a keystroke is met) and I shouldn't mess with User's systems configurations right? Anyway, I choose your answer because is what I was doing without NSTask :) – Diego Torres May 19 '11 at 05:37

phoxis · Answer 2 · 2011-05-18T14:14:22.153

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If the target process/program name which you want the PID is "processtolook" then you can use pidof command to get the PID of that running program.

pidof processtolook

have a look at the pidof manual. This is a part of sysvinit-tools package.

EDIT1: Have a look at this code i found: http://programming-in-linux.blogspot.com/2008/03/get-process-id-by-name-in-c.html

This might help you get you the outline.

edited May 18 '11 at 14:14

answered May 18 '11 at 14:06

phoxis

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Is the same as using "ps aux | grep processtolook | grep -v grep" conceptually, and i need to know of it during runtime, so it would be a while of "pidof processtolook" which is what i want to avoid. Besides, is not part of Mac OSX – Diego Torres May 18 '11 at 14:11
Have a look at the EDIT1, i have provided a link i found. – phoxis May 18 '11 at 14:14

score 0 · Answer 3 · answered May 18 '11 at 14:22

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On BSD you can use kvm_openfiles and kvm_getprocs to implement what you want. I don't know if it's available on OSX. If you have a pgrep program, look how it's implemented (src/bin/pkill.c).

answered May 18 '11 at 14:22

Mel

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Observe a Process of Unknown PID (no UI)

3 Answers3