Switching to the system Perl using perlbrew

Question

First, some background.

perlbrew is a tool to assist with the installation of Perl into a non-standard directory (usually under your home directory).

It also helps you control which Perl installation is used when executing perl in an interactive shell. Switching between installations is done using perlbrew use and perlbrew switch. perlbrew use only affects the current shell, while perlbrew switch is more permanent.

$ perl -V:version             |  $ perl -V:version
version='5.20.0';             |  version='5.20.0';
                              |
$ perlbrew use 5.18.2t        |  $ perlbrew switch 5.18.2t
                              |
$ perl -V:version             |  $ perl -V:version
version='5.18.2';             |  version='5.18.2';
                              |
$ bash -ic 'perl -V:version'  |  $ bash -ic 'perl -V:version'
version='5.20.0';             |  version='5.18.2';

perlbrew off is used to revert to using the system Perl, but it's temporary like perlbrew use. Is there a way to revert to the system Perl with the permanency of perlbrew switch?

Answer 1

To have perlbrew manage an installation of perl that wasn't installed by perlbrew, pick a name ("system" in my example) and create a link to its bin directory as follows:

cd "${PERLBREW_ROOT:-$HOME/perl5/perlbrew}"
mkdir perls/system
ln -s /usr/bin perls/system/bin

It will now appear in perlbrew list

$ perlbrew list
  ...
  system (5.10.1)
  5.18.2t
* 5.20.0t
  ...

And you'll be able to use perlbrew use and perlbrew switch.

$ perl -V:version
version='5.20.0';

$ perlbrew switch system

$ perl -V:version
version='5.10.1';

$ bash -ic 'perl -V:version'
version='5.10.1';

This works best with installations that have the same installbin, installvendorbin (if applicable) and installsitebin directories, as returned by

perl -V:'install.*bin'

---

By the way, a similar approach can be used to create aliases for perlbrew installs. For example,

 ln -s 5.26.1 perls/5.26           # Point to the latest release of a version.
 ln -s 5.26.1 perls/project_name   # Point to the install used by a project.