#!/usr/bin/perl
use strict;
use warnings;
use File::Temp ':POSIX';
use POSIX ':sys_wait_h';

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

my $tempfile = tmpnam();
my $output='';

die("ERROR create tempfile") unless($tempfile);

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

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

if($pid)
{
  # main process!

  my $time=time()+$timeout;
  # wait timeout seconds
  while($time > time())
  {
    # is process running?
    if(waitpid($pid, WNOHANG) == 0)
    {
      # wait 0.3 seconds
      select(undef,undef,undef,0.3);
      # or do something else
      # ...
    }
    else
    {
      # exit while loop
      last();
    }
  }

  # process running?
  if(waitpid($pid, WNOHANG)==0)
  {
    print "TIMEOUT KILL PROCESS\n";
    # force exit (softly)
    kill(9, $pid);
    $output='';
    unlink($tempfile);
  }
  else
  {
    # read written tempfile:
    if(open(my $fh, '<', $tempfile))
    {
      local $/=undef;
      $output=<$fh>;
      close($fh);
      if( !unlink($tempfile) )
      { warn("CAN'T REMOVE $tempfile ($!)\n"); }
    }
    else
    { warn("CAN'T OPEN $tempfile ($!)\n"); }
  }
}
else
{
  # forked process!

  # reopen STDOUT STDERR
  open(STDOUT, '>', $tempfile) or die("ERROR open $tempfile ($!)");
  open(STDERR, ">&STDOUT");

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

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

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