There are three methods to install perl modules: CPAN, CPANMINUS and CPANPLUS.
CPAN (cpan) is the original, basic method for installing perl modules. It comes with Perl, so you already have it and it has the most features. However it has a lot of configuration options that you need to customize when its first run.
CPANMINUS (cpanm) is a zero-configuration module installer that does the right thing for most users most of the time. It doesn’t come with Perl, but it’s easy to install. It integrates easily with local::lib.
CPANPLUS (cpanp) is a CPAN API that Perl programs can use, but it does have a shell that can be used to query, download and install modules. There are apparently no advantages to using this over CPANMINUS.
Aside: Unlike the bash shell, history and command completion will not work by default.
To enable them you need to install the perl modules:
Term::ReadKey and either of
Term::ReadLine::Gnu as shown below (using cpanm):
$ cpanm Term::ReadKey $ cpanm Term::ReadLine::Perl
Start it using either of the two following commands:
perl -MCPAN -e shell which starts the CPAN shell, or just type
$ cpan cpan> h <-- Shows help cpan> m Module::Name <-- This will search for a module by module name cpan> install Acme::Time::Baby <-- This will install a module
This is how to upgrade your cpan:
cpan> install Bundle::CPAN <-- Update your CPAN cpan> reload cpan
The first time you invoke cpan it will need to setup its configuration. Below is a transcript of a typical initial use where it sets up configuration:
~/$ perl -MCPAN -e shell Configuration will be written to: /shared/homes/xxxxxx/.cpan/CPAN/MyConfig.pm CPAN.pm requires configuration, but most of it can be done automatically. If you answer 'no' below, you will enter an interactive dialog for each configuration option instead. Would you like to configure as much as possible automatically? [yes] Warning: You do not have write permission for Perl library directories. To install modules, you need to configure a local Perl library directory or escalate your privileges. CPAN can help you by bootstrapping the local::lib module or by configuring itself to use 'sudo' (if available). You may also resolve this problem manually if you need to customize your setup. What approach do you want? (Choose 'local::lib', 'sudo' or 'manual') [local::lib] New urllist http://www.mirrorservice.org/sites/cpan.perl.org/CPAN/ http://ftp.sunet.se/pub/lang/perl/CPAN/ http://mirrors.xservers.ro/CPAN/ Autoconfiguration complete. PERL_MB_OPT="--install_base \"/shared/homes/xxxxxx/perl5\""; export PERL_MB_OPT; PERL_MM_OPT="INSTALL_BASE=/shared/homes/xxxxxx/perl5"; export PERL_MM_OPT; Would you like me to append that to /shared/homes/xxxxxx/.bashrc now? [yes] commit: wrote '/shared/homes/xxxxxx/.cpan/CPAN/MyConfig.pm' You can re-run configuration any time with 'o conf init' in the CPAN shell Terminal does not support AddHistory. cpan shell -- CPAN exploration and modules installation (v1.960001) Enter 'h' for help. cpan>
Note: This will have set some variables to be exported in .bashrc
You can view this configuration with ‘o conf’. Here is an example from my own directory.
cpan> o conf $CPAN::Config options from /shared/homes/xxxxxx/.cpan/CPAN/MyConfig.pm: commit [Commit changes to disk] defaults [Reload defaults from disk] auto_commit  build_dir [/shared/homes/xxxxxx/.cpan/build] ... lots more .... wget [/bin/wget] yaml_load_code  yaml_module [YAML] cpan>
Here is how to reconfigure specific variables:
o conf make_arg -I/shared/homes/xxxxxx/perl5 o conf make_install_arg -I/shared/homes/xxxxxx/perl5 o conf commit
I find it easier to just manually edit my .cpan/CPAN/MyConfig.pm
$ curl -L https://cpanmin.us | perl - App::cpanminus % Total % Received % Xferd Average Speed Time Time Time Current Dload Upload Total Spent Left Speed 100 314 0 314 0 0 788 0 --:--:-- --:--:-- --:--:-- 788 100 294k 100 294k 0 0 120k 0 0:00:02 0:00:02 --:--:-- 162k Working on App::cpanminus Fetching http://www.cpan.org/authors/id/M/MI/MIYAGAWA/App-cpanminus-1.7024.tar.gz ... OK Configuring App-cpanminus-1.7024 ... OK Building and testing App-cpanminus-1.7024 ... OK Successfully installed App-cpanminus-1.7024 1 distribution installed $
cpanminus at a boot time checks whether you have configured local::lib, or have the permission to install modules to the site_perl directory. If neither, it automatically sets up local::lib compatible installation path in a perl5 directory under your home directory.
This should have aleady been done when you installed perlbrew:
$ perlbrew install-cpanm $
You should be using the cpanm under perlbrew:
$ which cpanm ~/perl5/perlbrew/bin/cpanm
Switch to your installed perl e.g. 5.20.1
$ perlbrew switch perl-5.20.1
Now you can install cpan modules using cpanm.
Where Perl searches for Modules
This is a nice post on stackoverflow.com which explains how Perl finds Perl modules:
How is Perl’s @INC constructed
Search on Google for: “How is Perl’s @INC constructed? (aka What are all the ways of affecting where Perl modules are searched for?)”