#!/usr/bin/perl
use strict;

sub sys_alarm {
  my $cmd_result;
  my $cmd = shift( @_ );
  my $timeout = shift( @_ );
  eval {
    local $SIG{ALRM} = sub {die "alarm"};
    alarm $timeout;
    $cmd_result = `$cmd`;
    alarm 0;
  };
  if ($@) {
    print STDERR "Command \"$cmd\" timed out.\n";
    return undef;
  } else {
    return $cmd_result;
  }
}


my $x =  sys_alarm("sleep 10; echo foo", 5);
print "Output: " . $x  . "\n\n";