I was looking for a way to search CPAN from the command line in the same way that going to search.cpan.org does. This script will take a word to search for and find everything on CPAN that has that word in it. To use the script, just do

perl script.pl /undefined/
[download]

It'll find all all modules with undefined in its name. Note that it is case insensitive.

#!/usr/bin/perl 

use strict;
use warnings;
use CPAN;
use Module::CoreList;

my $d = shift @ARGV;
my @d = Module::CoreList->find_modules(qr/^$d$/);
my(@matches) =  grep(($_ eq $d), @d);   
if (@matches) {
     for $d (CPAN::Shell->expand("Module", "$d")) {
     print 
     "\n\tmodule: ",
     $d->id, "\n",
     "\tauthor: ",
     $d->cpan_userid, "\n",     
     "\tcurrent version: ", 
     $d->cpan_version, "\n",
     "\tinstalled version: ", 
     $d->inst_version, "\n";
     }
}
else {
     for $d (CPAN::Shell->expand("Module", $d)) {
     print 
     "\n\tmodule: ",
     $d->id, "\n",
     "\tauthor: ",
     $d->cpan_userid, "\n",
     "\tThe current version is: ",
     $d->cpan_version, "\n",
     "\tinstalled version: ",
     $d->inst_version, "\n";
     }
}
[download]

It'll also take a module name like CGI and find eveything on CPAN that has CGI in its name.

perl script.pl /CGI/
[download]