my $start = time;
sub exec_time { return time - $start }
my $yawn;
eval {
    local $SIG{ALRM} = sub { die "alarm\n" };
    alarm 5;
    $yawn = `sleep 3600 ; echo "yawn"`;
    alarm 0;
};
printf "Time: %d\n", exec_time();
print $@ ? 'Timed out.' : 'Finished.';
print "\n";
print "yawn? $yawn\n";
__END__
Time: 5
Timed out.
yawn?