Elegantly get list of children processes

Question

I would like to get a list of all the processes whose parent is $pid. This is the simplest way I've come up with:

pstree -p $pid | tr "\n" " " |sed "s/[^0-9]/ /g" |sed "s/\s\s*/ /g"

Is there any command, or any simpler way to get the list of children processes?

Thanks!

Answer 1

Yes, using the -P option of pgrep,

i.e pgrep -P 1234 will get you a list of child process ids.

Answer 2

pids of all child processes of a given parent process <pid> id is present in /proc/<pid>/task/<tid>/children entry.

This file contains the pids of first-level child processes. Do it recursively for whole process tree.

head over to https://lwn.net/Articles/475688/ for more information.