What's the easiest way to install a missing Perl module?

On Unix:

usually you start cpan in your shell:

$ cpan

and type

install Chocolate::Belgian

or in short form:

cpan Chocolate::Belgian

On Windows:

If you're using ActivePerl on Windows, the PPM (Perl Package Manager) has much of the same functionality as CPAN.pm.

Example:

$ ppm
ppm> search net-smtp
ppm> install Net-SMTP-Multipart

see How do I install Perl modules? in the CPAN FAQ

Many distributions ship a lot of perl modules as packages.

• Debian/Ubuntu: apt-cache search 'perl$'
• Arch Linux: pacman -Ss '^perl-'
• Gentoo: category dev-perl

You should always prefer them as you benefit from automatic (security) updates and the ease of removal. This can be pretty tricky with the cpan tool itself.

For Gentoo there's a nice tool called g-cpan which builds/installs the module from CPAN and creates a Gentoo package (ebuild) for you.

Try App::cpanminus:

# cpanm Chocolate::Belgian

It's great for just getting stuff installed. It provides none of the more complex functionality of CPAN or CPANPLUS, so it's easy to use, provided you know which module you want to install. If you haven't already got cpanminus, just type:

# cpan App::cpanminus

to install it.

It is also possible to install it without using cpan at all. The basic bootstrap procedure is,

curl -L http://cpanmin.us | perl - --sudo App::cpanminus

For more information go to the App::cpanminus page and look at the section on installation.

I note some folks suggesting one run cpan under sudo. That used to be necessary to install into the system directory, but modern versions of the CPAN shell allow you to configure it to use sudo just for installing. This is much safer, since it means that tests don't run as root.

If you have an old CPAN shell, simply install the new cpan ("install CPAN") and when you reload the shell, it should prompt you to configure these new directives.

Nowadays, when I'm on a system with an old CPAN, the first thing I do is update the shell and set it up to do this so I can do most of my cpan work as a normal user.

Also, I'd strongly suggest that Windows users investigate strawberry Perl. This is a version of Perl that comes packaged with a pre-configured CPAN shell as well as a compiler. It also includes some hard-to-compile Perl modules with their external C library dependencies, notably XML::Parser. This means that you can do the same thing as every other Perl user when it comes to installing modules, and things tend to "just work" a lot more often.