memory usage script

#!/usr/bin/env perl
use strict;
use warnings;
use Devel::MemUsed;
use Term::ReadLine;

my $term = Term::ReadLine->new('Memory Shell');

while ( defined (my $line = $term->readline('perl> ')) ) { 
    last unless $line;

    my $pid = fork();
    if ($pid) {
        # parent
        wait();
    } elsif (defined $pid) {
        my $memused  = Devel::MemUsed->new;
        eval $line;
        print "$memused\n";
        exit();
    } else {
        die "fork error : $!";
    }   
}