PID after fork && exit

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

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Re: PID after fork && exit by edan (Curate) on May 12, 2003 at 16:12 UTC
`$$` will always give you the current process ID: `print "PID before fork: $$\n"; fork && exit; print "PID after fork: $$\n";` [download] Output: `PID before fork: 21314 PID after fork: 21315` [download] (Your mileage may vary) -- 3dan	[reply] [d/l] [select]
Re: PID after fork && exit by Fletch (Bishop) on May 12, 2003 at 16:07 UTC
Read `perldoc perlipc` and `perldoc perlvar` harder. `perl -le 'print "parent pid $$"; if( my $p = fork ) {print "parent got + child $p"; exit; } else { print "child pid $$"; exit }'` [download]	[reply] [d/l] [select]
Re: PID after fork && exit by smitz (Chaplain) on May 12, 2003 at 16:00 UTC
`fork` returns the child PID, or 0 for the parent, AFAIK Smitz	[reply] [d/l]
Re: PID after fork && exit by Abigail-II (Bishop) on May 12, 2003 at 20:23 UTC
That's very confusing what you write. If `fork` fails, `undef` is returned. If `fork` succeeds, different values are returned in the parent and the child. In the child, `fork` returns `0`, while in the parent, the process ID of child is returned. This is the only convenient time for the parent to get the process ID of the child. A parent can get the process ID of the child when it's reaping the child with some form of `wait` call, but then the child has already finished. Otherwise, the parents rests nothing else than walking the process list. Abigail	[reply] [d/l] [select]
Re: PID after fork && exit by neilwatson (Priest) on May 12, 2003 at 16:17 UTC
Thanks. Neil Watson watson-wilson.ca	[reply]