#!/usr/bin/perl

use strict;
use warnings;
use 5.010;

use File::Basename;
my $pname; BEGIN { ($pname)=fileparse $0, qr/\.pl/i }

my $TIME = 10;

if (@ARGV) {  # Working as a generic external program
    sleep +(my $time=shift);
    say "Slept $time seconds";
} else {      # Example of timeout via alarm()
    my ($msg, $timeout) = ("died in SIG ALRM", int rand 2*$TIME);
    eval {
        local $SIG{ALRM} = sub {die $msg};
        warn "[$pname] Trying to collect output from external program.\n",
             "(Setting timeout to $timeout seconds.)\n";
        alarm($timeout);
        chomp(my $output = qx/perl $0 $TIME/);
        say "The output got from external program is: `$output'";
        alarm(0);
    };
    if ($@ and $@ ~~ /\Q$msg/) {
        warn "[$pname] Timed out!\n";
    }
}

__END__