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Re^2: Child process inter communication

by tybalt89 (Monsignor)
on Jun 14, 2017 at 21:04 UTC ( #1192835=note: print w/replies, xml ) Need Help??

in reply to Re: Child process inter communication
in thread Child process inter communication

Here's my second guess, using named pipes (fifos);

#!/usr/bin/perl # use strict; use warnings; use IO::Select; use POSIX qw(mkfifo); my $childcount = 3; my $hasterminal = 1; my %who; my $fifodir = '/tmp'; for my $me (1 .. $childcount) { if( my $pid = fork ) # parent { $who{$pid} = $me; } elsif( defined $pid ) # child { my $mypath = "$fifodir/$$.fifo"; mkfifo( $mypath, 0700 ) or die "$! on making mypath"; open my $fifo, '+<', $mypath or die "$! opening $mypath"; my $sel = IO::Select->new($fifo); $me == $hasterminal and $sel->add(*STDIN); while(1) { for my $handle ($sel->can_read) { defined( my $command = <$handle> ) or exit; print "$$ got $command"; if( $command =~ /^(\d+)\s+(.*\n)/ ) { my $otherpath = "$fifodir/$1.fifo"; if( -p $otherpath and open my $otherchild, '>', $otherpath ) { print $otherchild $2; close $otherchild; } else { warn "child $1 does not have a fifo\n"; } } } } } else { die "fork failed with $!"; } } use Data::Dump 'pp'; pp \%who; my $pid = wait; # on first exit, kill rest print "$who{$pid} exited\n"; kill 15, keys %who; unlink map "$fifodir/$_.fifo", keys %who; print "$who{$pid} exited\n" while ($pid = wait) > 0;

Enter a pid followed by white space and a message, it will forward the message to that pid.

Example - enter:

25910 somemessage

to get

25908 got 25910 somemessage 25910 got somemessage

Of course, using your actual pids.

Replies are listed 'Best First'.
Re^3: Child process inter communication
by marioroy (Prior) on Jun 15, 2017 at 19:21 UTC

    That is cool tybalt89. I understand it now after reading this line. Ah, it's the first child who is listening on STDIN ;-)

    $me == $hasterminal and $sel->add(*STDIN);

    Regards, Mario

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