#!/usr/bin/perl
use warnings;
use strict;

my $script = 'ps auxww';

eval {

    # from http://www.rocketaware.com/perl/perlfunc/alarm.htm
    local $SIG{ALRM} = sub { die "alarm\n" };  # NB \n required
    alarm(5);                        # set time limit to 5 sec
    system($script);
    alarm(0);    # if $script finishes in <5sec reset alarm
};
die if $@ && $@ ne "alarm\n";    # propagate errors

if ($@) {
    print "Timeout!  [$@]\n";

    # do stuff if eval fails (eg timeout)
}