The CPAN module has all sorts of code to do stuff like this. The man page has some very interesting examples, including one that I think you can modify to suit your needs: 
# list all modules on my disk that have newer versions on CPAN
  for $mod (CPAN::Shell->expand("Module","/./")) {
    next unless $mod->inst_file;    
    next if $mod->uptodate;

    printf "Module %s is installed as %s, could be updated to %s\n",
      $mod->id, $mod->inst_version, $mod->cpan_version;  
  }

[download]
$mod->inst_version is set to the installed version of your module and $mod->cpan_version is the latest available version. The expand function as done above will pull everything from CPAN.

In reply to Re: What modules are installed ? by Fastolfe
in thread What modules are installed ? by cajun

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