Perl and modules
================

You can now manage, as with other langages, your own repository for perl modules, using ``cpanminus``.

.. note::

    ``cpanminus`` and ``perlbrew`` are already installed on the base system.

Using CPANminus
---------------

If you want to use the base system Perl (``perl -V``), you only have to use ``cpanminus``. Configure it (to use ``~/perl5.32/``) by running this command:

.. code-block:: bash

    $ cpanm --local-lib=~/perl5.32 local::lib && eval $(perl -I ~/perl5.32/lib/perl5/ -Mlocal::lib)

If you have errors like ``/usr/bin/perl: symbol lookup error`` and/or ``undefined symbol``, you may have a version mismatch (existing or old installation in your *$HOME*). Change the destination directory (``~/perl5.32``), or erase the existing one.

You have to add, at the end of your ``~/.bashrc``, these lines:

.. code-block:: bash

    # PSMN11 / local cpanminus / force user's CPAN path
    export PERL_MB_OPT="--install_base \"${HOME}/perl5.32\""
    export PERL_MM_OPT="INSTALL_BASE=${HOME}/perl5.32"
    export PERL5OPT="-I${HOME}/perl5.32/lib/perl5 -I${HOME}/perl5.32/lib/perl5/site_perl"
    if [[ -d "${HOME}/perl5.32/lib/perl5" ]]; then
        export PERL5LIB="${HOME}/perl5.32/lib/perl5:${PERL5LIB}"
    fi

Then reload that file (``source ~/.bashrc``) or disconnect/reconnect for it to modify your environment.

Install Perl modules
~~~~~~~~~~~~~~~~~~~~

Every needed module can now be installed like this (ex: *YAML::Tiny*):

.. code-block:: bash

    $ cpanm YAML::Tiny

Your installed modules are located in ``${HOME}/perl5.32/lib/perl5``. See ``man cpanm`` for more.

Install your own Perl
---------------------

**For more advanced users**: You can build your own Perl. The simplest way is by using ``perlbrew``.

Initialize perlbrew
~~~~~~~~~~~~~~~~~~~

.. code-block:: bash

    $ perlbrew init

    perlbrew root (~/perl5/perlbrew) is initialized.

Then, as asked, add ``source ~/perl5/perlbrew/etc/bashrc`` at the end of your ``~/.profile``, then *source* your ``~/.profile`` (or disconnect-reconnect) for it to be loaded properly.

.. note:: You can change the default installation directory (``$HOME/perl5/perlbrew``) to a group storage (see :doc:`../filesystems/storages`), if needed. See ``$PERLBREW_ROOT`` in *perlbrew* man page.

Test it :

.. code-block:: bash

    $ perlbrew version
    /usr/bin/perlbrew  - App::perlbrew/0.91

.. warning:: If you ``self-install`` or ``upgrade`` *perlbrew*, there will be two versions : your own, and the one already installed on the system (which remain active).

Install a version of Perl
~~~~~~~~~~~~~~~~~~~~~~~~~

.. code-block:: bash

    $ perlbrew available
    # perl
    perl-5.35.8
    perl-5.34.0
    perl-5.32.1
    perl-5.30.3
    perl-5.28.3
    [...]

Installation might take a while :

.. code-block:: bash

    $ perlbrew install perl-5.35.8

    [a certain amount of successfull logs]

Install a local CPANminus
~~~~~~~~~~~~~~~~~~~~~~~~~

First, select your own Perl installation:

.. code-block:: bash

    $ perlbrew use 5.35.8

Install the cpanminus module with:

.. code-block:: bash

    $ curl -L https://cpanmin.us | perl - App::cpanminus

Verify with these two commands:

.. code-block:: bash

    $ perlbrew list-modules
    App::cpanminus


.. code-block:: bash

    $ which cpanm
    /home/mylogin/perl5/perlbrew/perls/perl-5.35.8/bin/cpanm

.. warning:: You have now two versions of ``cpanminus``, the one from your *perlbrew* installation, and the one from the system (which remain active).

Add modules to your CPANm
~~~~~~~~~~~~~~~~~~~~~~~~~

Same as above, using the ``cpanminus`` from your ``perlbrew`` installation (ex: *Log::Logger*):

.. code-block:: bash

    $ cpanm Log::Logger

Verify with:

.. code-block:: bash

    $ perlbrew list-modules
    App::cpanminus
    Log::Logger

.. warning:: Do not install too many Perl versions (for space reasons), and use ``perlbrew clean`` on a regular basis.

See `this tutorial <https://www.digitalocean.com/community/tutorials/how-to-install-perlbrew-and-manage-multiple-versions-of-perl-5-on-centos-7>`_ for more.