This book discusses many Perl modules that may not be included with your system. This appendix contains instructions for installing modules from CPAN. It also discusses how to use perldoc to access documentation.
CPAN is the Comprehensive Perl Archive Network, found at http://www.cpan.org/ and at numerous mirrors around the world (see http://www.cpan.org/SITES.html). From CPAN you can download source code and binary distributions of Perl, plus all of the modules we mentioned in this book and many other scripts and modules.
You can browse the very long list of modules at http://www.cpan.org/modules/00modlist.long.html. If you know the name of a module you wish to download, then you can generally find it via the first word of the module’s name. For example, you can download Digest::MD5 from http://www.cpan.org/modules/by-module/Digest/. The filename within that directory is Digest-MD5-2.09.tar.gz (note that the version number, 2.09, will likely change by the time you read this book).
All Perl modules distributed on CPAN follow a consistent install process, but some modules are easier to install than others. Some have dependencies on other modules, and some include C source code that must be compiled and often linked to other libraries on your system.
You may have difficulty compiling the modules that contain C code. Most commercial distributions of Unix do not include an ANSI C compiler. You can generally obtain a prebuilt binary of the ...