in reply to How do I know if a package is on my server?

And how would I go about seeing if the package/module *is* on the server using some script?

Easy - try to use the module, if that fails, it is not there. At least it is not found in any path included in perl's built-in array @INC.

So how do these things work?

What kind of "hosting server" do you have? what kind of access? Is it a server with shell access (i.e. ssh) or a plain web server?

Perl comes with many modules included, two of them are Config and Module::CoreList. The latter can be used to list all core modules: 

# command line
$ perl -lE 'use Module::CoreList; say for Module::CoreList->find_modul
+es'
# CGI
#!/usr/bin/perl
use Module::CoreList;
use 5.10.0;
say "Content-type: text/html\n";
say <<EOH;
<html><head><title>CoreList</title></head>
<body><h1>Perl Core Modules:</h1>
<pre>
EOH
say for Module::CoreList->find_modules;
say "</pre></body></html>";

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The Config module exports the hash %Config which holds all information about how perl was built, including paths for module inclusion search (which, again, show up in @INC). The relevant keys are

In a sane setup, the core modules root is $Config{privlib}. All vendor provided modules of the platform live in vendorlib, the modules specific for the site are in sitelib.

You can prepend an arbitrary directory to @INC using the lib module 

use lib '/path/to/my/modules';

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which ensures that modules are first looked for in there.

This bunch of information should be enough to enable you to answer the rest of your questions by yourself.

perl -le'print map{pack c,($-++?1:13)+ord}split//,ESEL'

In Section Seekers of Perl Wisdom