Here is the bare bones way to do it. You didn't say exactly what your problem was in the code.

#!/usr/bin/perl
use warnings;
use strict;


my %pids;

my @to_be_processed = (1..20);

my $cmd = 'echo';

foreach my $p (@to_be_processed){ 
   $pids{$p}{'pid'} = open($pids{$p}{'fh'}, "$cmd $p 2>&1 |");
}

foreach my $key(keys %pids){ 
  my $fh = $pids{$key}{'fh'};
  while (<$fh>){
    print $_;
    #stuff data here into a return hash
   }
}



foreach my $key(keys %pids){
   waitpid($pids{$key}, 1);
}

print "done\n";
[download]

# setup 2 way communication (pipe?)

Use IO::Pipe ;-) There are a few good examples on google. I have an easy to understand example at: Using Select and pipes to communicate with threads. It is using threads instead of fork, but the IO::Pipe concepts are clear and should be the same.

I'd go with IO::Select and IO::Handle (maybe IO::Pipe as well), these modules are core. The following may serve as inspiration.

use IO::Handle;
use IO::Select;

my %pids;    # kid job description keyed on pid
my $kids_fh; # pipe filehandles foreach kid keyed on fileno

my $rset = IO::Select->new;
local $| = 1;

local $SIG{CHLD} = sub {
    my $waitedpid = wait;
    print "process $waitedpid ($pids{$waitedpid}) finished" if $waited
+pid > 0;
};

# spawn childeren

for my $cmd( @cmds ) {
    ;
    my ($rh,$wh);
    for ($rh,$wh) {
        $_ = IO::Handle->new;
        $_->autoflush;
    }
    pipe($rh,$wh);

    if ((my $pid = fork) == 0) {
        # child code
    } else {
        # parent
        $rset->add($rh);
        $pids{$pid} = $cmd;
        $kids_fh{fileno($rh)} = $pid;
    }
}

# now interact with kids

while(1) {
    last unless $rset->handles;
    foreach my $rh (sort { fileno $a <=> fileno $b } $rset->can_read) 
+{
        my $response = do { local $/; <$rh> };
        ...
        ...
        $rset->remove($rh);
    }
}
[download]

foreach my $rh (sort { fileno $a <=> fileno $b } $rset->can_read) {

Why sort the ready handles by fileno?

---

With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday'

Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.

"Science is about questioning the status quo. Questioning authority".

In the absence of evidence, opinion is indistinguishable from prejudice.

Good catch, thank you. Well, er... first come, first serve. Children always have an eye on each others privileges. ;-)

Seriously, it's an artifact from cut&paste. In the code I took that from, processing had preferably to be in the same order as the spawned children. Not a technical requirement.

perl -le'print map{pack c,($-++?1:13)+ord}split//,ESEL'

So I'm falling back on the oldschool Fork and process method.