CODEWITHSUNDEEP
clinuxprocess
linuser
linuser

Reputation: 23

Get child list of parent process in C

I have a PID of process that may contain childs. How can I get the PID of all child processes? I make my own PTY handler, so when user run a shell in this handler he may run anymore programs ( directly from shell ), every ran program becomes a child of shell. So, when I press Ctrl+C I need to send signal to the most new process, so need to know PID of that last one.

Upvotes: 1

Views: 3334

Answers (1)

Basile Starynkevitch
Basile Starynkevitch

Reputation: 1

You should keep explicitly all the pids (result of fork(2)...) of your child processes (and remove a pid once you waited it successfully with wait(2) etc...)

It is up to you to choose the data structures to keep these pids.

Any other approach (e.g. using proc(5)... which is what ps and pstree are doing.) is not very portable and inefficient.

So the basic rule is that every time you call fork you should explicitly keep its result (and test for the 3 cases: 0 if in child process, >0 if in parent process, <0 on error) and use that at wait time.

Read Advanced Linux Programming; it has many pages relevant to that subject.

You might also be interested by process groups and sessions. See setpgrp(2), setsid(2), daemon(3), credentials(7) etc. Notice that with a negative or zero pid kill(2) can send a signal to a process group, and that you could also use killpg(2) for that purpose.

Upvotes: 1

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