> cat perl.pl
#!/usr/bin/perl

eval {
  $SIG{ALRM} = sub { die "Timed out\n"; };
  alarm(5);
  `perl -e 'while(1){sleep 1;}'`;
  alarm(0);
};
print "Died with: $@\n";

> ./perl.pl
Died with: Timed out

> ps
  PID TTY          TIME CMD
11551 pts/0    00:00:00 bash
11648 pts/0    00:00:00 perl
11651 pts/0    00:00:00 ps