system command with a timeout. (Unix only)

my_system.pl

# my_system($command, $timeout = 10) [Unix]
sub my_system($;$) {
  use POSIX qw(:sys_wait_h);

  my $command = $_[0];
  my $timeout = $_[1] || 10;

  my $pid = fork();
  if (!defined($pid)) {
    return -1;  # failed to fork
  }
  if ($pid == 0) {
    setpgrp();
    exec($command);
    exit(255);  # failed to exec
  } else {
    while ($timeout > 0) {
      my $ret = waitpid($pid, POSIX::WNOHANG);
      if ($ret != 0) {
        # finished
        return $? / 256;
      }
      $timeout--;
      sleep(1);
    }
    # timeout
    kill(-9, getpgrp($pid));
    waitpid($pid, 0);
    return -2;
  }
}