How to get the PID of an invoked process

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

From inside my perl script I want to invoke an external program using system("blah"); is there a way to get the PID of the invoked process without resorting to `ps -ef` and then parsing this? Thanks in advance.

Comment on How to get the PID of an invoked process

Replies are listed 'Best First'.
Re: How to get the PID of an invoked process by LD2 (Curate) on Jul 21, 2001 at 01:31 UTC
You may want to use Super Search first - there is a good chance that someone in the past has discussed something similar :) Check out this node: Process ID of a Launched Program	[reply]
Re: How to get the PID of an invoked process by IraTarball (Monk) on Jul 21, 2001 at 01:43 UTC
If you need the PID you might want to look at `fork` and `exec`. `fork` will return the childs pid, you can then have the child `exec` the system call. As I understand it, this is what `system()` does at it's core. Check out `perldoc -f fork` and `perldoc -f exec` for examples and details. I wrote the following that seems to work, no error checking though. `use strict; use warnings; $SIG{CHLD} = '"IGNORE"'; my $child = fork(); if ($child) { print "I'm the parent, I think I'll wait for the child $child...\n +"; waitpid($child, 0); } else { exec ("ls"); }` [download] Good Luck, Ira. "So... What do all these little arrows mean?" ~unknown	[reply] [d/l] [select]
(redmist) Re: How to get the PID of an invoked process by redmist (Deacon) on Jul 21, 2001 at 01:33 UTC
From perldoc perlvar. `$PROCESS_ID $PID $$ The process number of the Perl running this script. You should conside +r this variable read-only, although it will be altered across fork() +calls. (Mnemonic: same as shells.)` [download] redmist Silicon Cowboy	[reply] [d/l]
Re: How to get the PID of an invoked process by Anonymous Monk on Jul 21, 2001 at 02:15 UTC
Thanks to all! I'm happily fork'ing/exec'ing away now...	[reply]

Back to Seekers of Perl Wisdom