If you’re running the standard distribution of Perl, on either a Unix or Win32 system, and you want to install a module, this section explains how to do it. If you are running the ActiveState Win32 port, you can follow the instructions covered in this section, unless you’re running on a system without a development toolkit; if this is the case, see the next section.

Before installing modules, you should understand at least a little about make. make is a command designed to automate compilations; it guarantees that programs are compiled with the correct options and are linked to the current version of program modules and libraries. But it’s not just for programmers—make is useful for any situation in which there are dependencies among a group of related files.

make uses a file known as a Makefile, which is a text file that describes the dependencies and contains instructions that tell make what to do. A Perl programmer who writes a module creates a file called Makefile.PL that comes with the module when you download it. Makefile.PL is a Perl script that uses another module, ExtUtils::MakeMaker (generally referred to as simply MakeMaker), to generate a Makefile specific to that module on your system.

Before you can actually install the module, you need to decide where it should go. Modules can be installed either globally, for everyone to use, or locally, for your own use. Most system administrators install popular software, including Perl modules, to be globally available. In that case, the modules are generally installed in a branch of the lib directory with the rest of the Perl libraries.

If you have root privileges or write access to the locations where Perl modules are installed on your system, you can proceed by moving the downloaded module file to the correct directory and running gunzip and tar to unpack it. Then cd to the module directory and check any README or INSTALL files, check the MANIFEST file to be sure everything is there. If all is well, you can run the following to complete the installation:

% perl Makefile.PL
% make
% make test
% make install

If you’re on a Win32 platform and are using Mingw32, do the following:

C:modulename-version> perl Makefile.PL
C:modulename-version> dmake
C:modulename-version> dmake test
C:modulename-version> dmake install

It’s possible that you’ll need to customize Makefile.PL before running it. If so, see the discussion of ExtUtils::MakeMaker in Chapter 8. Or, if you know the MakeMaker options that you’d like to add to Makefile.PL, you can add these options on the command line. A typical scenario would be on a system where you’ve installed a precompiled version of Perl, and the CC and LD options in Config.pm don’t match your programming environment; thus, Perl modules won’t build correctly. To solve this problem, you can do the following:

% perl Makefile.PL CC=gcc LD=gcc

If you are going to install the module locally (for example, if you don’t have permission to install globally or you want to test it locally before installing it for general use), you need to pass a PREFIX argument to Perl when you run Makefile.PL to generate the Makefile. This argument tells MakeMaker to use the directory following PREFIX as the base directory when installing the module.

For example, to install a module in the directory /home/mydir/Perl/Modules, the PREFIX argument would look like this:

% perl Makefile.PL PREFIX=/home/mydir/Perl/Modules

Then follow the remaining steps, as above:

% make
% make test
% make install

The module is now available, but when you write Perl code to use the module, there’s another detail to take care of. Since Perl looks in system-wide directories as specified in the special array @INC, it won’t find local modules unless you tell it where they are. Instead, you’ll receive an error message such as the following:

Can't locate <ModuleName>.pm in @INC.
BEGIN failed--compilation aborted.

Thus, if you installed the module in /home/mydir/Perl/Modules, you need to tell Perl to look in that location with the command use lib ' path ':

#!/usr/local/bin/perl -w
use lib '/home/mydir/Perl/Modules';
use ModuleName;