List the Modules in Your System

Here is some pretty good code piece to check it:

#!/usr/bin/perl
use strict;
use ExtUtils::Installed;

my $inst=ExtUtils::Installed->new();

my @modules = $inst->modules();

foreach(@modules){
        my $ver = $inst->version($_) || "???";
        printf("%-12s -- %s\n",$_,$ver);
}

exit;