eval {

        local $SIG{'ALRM'} = sub { die "timed out\n" };

        alarm(10);
        system("sleep 30; echo 'I made it'") && die "system call failed\n";
        alarm(0);

};
if ($@) {
        if ($@ eq "timed out\n") {
                print "I timed out\n";  
        }
        else {
                print "something else went boom\n";
        }
}
else {
        print "I didn't time out\n";
}



##</code><code>##

-- first.pl -- 
#!/usr/bin/perl

use strict;

my $pid;
eval {

        local $SIG{'ALRM'} = sub { die "timed out\n" };

        alarm(10);

        $pid = fork;
        if ($pid == 0) {
                exec("./second.pl");
        }
        else {
                wait;
        }

        alarm(0);

};
if ($@) {
        if ($@ eq "timed out\n") {
                kill(15,$pid);
                print "I timed out\n";  
        }
        else {
                print "something else went boom\n";
        }
}
else {
        print "I didn't time out\n";
}

-- second.pl -- 
#!/usr/bin/perl

while(1) {
        print "alive\n";
        sleep(1);
}

##</code><code>##

darkstar:~>./first.pl 
alive
alive
alive
alive
alive
alive
alive
alive
alive
alive
I timed out
darkstar:~>