Ævar Arnfjörð Bjarmason

In May I decided to stop using Debian's perl 5.10.1 in favor of using a 5.13.1 built with perlbrew, and CPAN modules built with cpanminus. It's been great, here's how I did it.

Before switching over I ignored Debian's perl library packages, and installed everything with cpanm into /usr/local. But since I wanted to use the new post-5.10 features of Perl I thought I might as well replace all of it and use a newer perl.

What I did:

• Created a v-perlbrew user. All users on the server can use this centrally managed Perl and its modules
• Added this to everyone's .bashrc: test -f ~/perl5/perlbrew/etc/bashrc && source ~/perl5/perlbrew/etc/bashrc
• Made a list of CPAN modules that I need. When I upgrade the perlbrew perl I can just run grep -v ^# cpan-modules | cpanm to get all the required modules with the new perl.
• Ran around changing PATH in crontabs, Apache settings etc. so that everything that isn't internal to Debian itself uses perlbrew's perl instead of /usr/bin/perl.

Getting the PATHs right everywhere turned out to be the hardest part. A lot of things in Debian have a path like /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/X11R6/bin. I haven't found out how to change that, presumably some of them are hardcoded into executables like bash.

To get around that I have to hardcode the PATH to perlbrew in every crontab that uses perl. For a full list of these and other changes I've made the output of git --git-dir /etc/.git log -p --reverse -Sperlbrew available as a Gist.

The only caveat I've encountered is that there's one global perlbrew bashrc in ~/perl5/perlbrew/etc/bashrc. So if I can't use perlbrew switch to only switch some users onto a given perl. It would be neat if perlbrew supported having the current symlinks in a local ~/perl5 while the actual binaries and modules were in ~v-perlbrew/perl5.