Classnotes | UNIX01 | RecentChanges | Preferences One of Perl's programming strengths is in the fact that you can call on and snap in new functionality through the use of objects called "Modules".
A Perl Module is slightly like a library in another application, except more atomic than standard libraries are. A piece of Perl code and be both a stand alone script and a module for snapping into another external application.
Perl Modules can usually be installed rather easily using the Comprehensive Perl Archive Network, CPAN (http://cpan.org/), and there are Modules for just about every need you could ever have.
A modules is added to a Perl script with the "use" command. For example, if in my script I wanted to use the POSIX module, I would add the following at the beginning
use POSIX;
You can also specify specific functions or procedures from a module by including those functions in single-quotes. For example, if all I wanted from POSIX was the "strftime" function, my syntax would be
use POSIX 'strftime';
Sometimes, a specific module will have a sub-module (or several layers of sub-modules). These can be specified using the "::" deliminator. For example, if I wanted the File module's Copy submodule, I would have
use File::Copy;
Occassionally, you may have need for a Perl script to run using a certain version of Perl. Sometimes multiple versions of Perl exist on a given system for maximum compatibility. Passing a version number to "use" will allow you to specify the version needed.
