#!/usr/bin/perl
use strict;
use warnings;
use IO::Pipe;
use POSIX qw(:sys_wait_h);

my $timeout = 5;
my @cmd=('perl', '-e', '$|=1; for(0..2){print qq(TEST $_\n); warn(qq(TTTT $_\n)); sleep(1); }');

my $output='';

# create pipe
my $pipe = IO::Pipe->new();

# split in two independent processes
my $pid = fork();

# fork failed!
die('Fork failed!') unless(defined($pid));

if($pid)
{
  # main process!
  $pipe->reader();
  $pipe->blocking(0);

  my $time=time()+$timeout;

  # wait timeout seconds
  while($time > time())
  {
    # is process running?
    if(waitpid($pid, WNOHANG) == 0)
    {

      # read all aviable
      if(my @data=<$pipe>)
      { $output.=join('',@data); }

      # do something else
      print "WAIT\n";
      select(undef,undef,undef,0.3);
      # ...
    }
    else
    {
      # exit while loop
      last();
    }
  }

  # process running?
  if(waitpid($pid, WNOHANG)==0)
  {
    print "TIMEOUT KILL PROCESS\n";
    # force exit (softly)
    kill(9, $pid);
    $output='';
  }
}
else
{
  # forked process!

  $pipe->writer();
  $pipe->autoflush(1);

  # reopen STDOUT and STDERR
  open(STDOUT, ">&", $pipe);
  open(STDERR, ">&STDOUT");
  close($pipe);

  # start programm with actual process id
  exec(@cmd);

  # error???
  die("EXEC Failed! ($!)");
}

if($output)
{
  print "OUTPUT:\n";
  print $output;
}
else
{
  print "NO OUTPUT!\n";
}