#!/usr/bin/perl
use strict;
use warnings;
use Data::Dumper;

my @return;
eval {
    local $SIG{ALRM} = sub { die "alarm\n" }; # NB: \n required
    alarm 5;
    @return = `./test.pl`;
    alarm 0;
};

if( $@ ) {   # CASE: Command timed out
    die unless $@ eq "alarm\n";   # propagate unexpected errors
}
else {       # CASE: Did *not* timeout
}

print Data::Dumper->Dump([\@return],['return']);