#!/usr/bin/perl

## Init the detached codes:
sub DETACH_INIT {
  my ( $x ) = @_ ;
  $| = 1 ;  ## Flush STDOUT or will lock some threads on Win32.
  $SIG{CHLD} = \&REAPER ; ## Who will lead with childs on real fork.

  ## Run $x times the detached codes:
  my $wpid = 0 ;
  for my $i (1..$x) {
    next if $wpid ; ## Next until the wait() is on.
    &SPAWN($i) ;
  }

  ## Wait for the childs.
  sub REAPER{
    $wpid = wait ;
    $SIG{CHLD} = \&REAPER ;
  }

  ## Make the fork, start the detached code, than continue main code.
  ## When the detached code return, make an exit of the forked process or thread.
  sub SPAWN {
    my ( $id ) = @_ ;
    my $pid ; 
    if (!defined($pid = fork)) { print "cannot fork: $!\n" ; return ;}
    elsif ($pid) { return ;}
    exit &DETACHED_CODE($id) ;
  }
}

## Code to be runned detached:
sub DETACHED_CODE {
  my ( $id ) = @_ ;
  
  for(0..10) {
    print "$id>> $_\n" ;  
    sleep(1);
  }
}

  ## Tell to start 2 detached codes:
  &DETACH_INIT(2) ;

  ## Some main code to continue:
  for(0..10) {
    print "main>> $_\n" ;
    sleep(1);
  }


##</code><code>##

my $cmd = "$^X foo.pl arg1" ; ## $^X is the path to perl(.exe) interpreter.
open (CMDLOG,"| $cmd") ; close (CMDLOG) ;

##</code><code>##

open (CMDLOG,"| $cmd") ;
## Now you can continue your main (caller) script...

##</code><code>##

use IPC::Open3 ;
my $cmd = "$^X foo.pl arg1" ;
open3(LOGREAD , LOGERROR, LOGWRITE, "$cmd");
my @log = (<LOGREAD> , <LOGERROR>) ;
close(LOGREAD , LOGERROR, LOGWRITE) ;
print "@log\n" ;

##</code><code>##

open (CMDLOG1,"| $cmd1") ;
open (CMDLOG2,"| $cmd2") ;
open (CMDLOG3,"| $cmd3") ;