Perl module version

Question

I have a couple of perl modules installed in the $HOME of my web server. The web server used to run perl 5.8.8 so they were installed under $HOME/perl/lib/perl5/5.8.8/...

During a server migration, the web hosting company changed perl to 5.10.1 but I did not know about this until my scripts started failing. I managed to do a quick dirty fix by copying the 5.8.8 tree to 5.10.1 and it seems to work OK now, but I want to avoid my scripts failing like this in future.

What is the best way of allowing my scripts to use the locally stored modules under the 5.8.8 folder even if the perl version gets upgraded again?

I can add a check for the expected perl version in my scripts and email myself if it changes, but it's too late by then as the script may have failed several times before I can fix the problem. Ideally I want to prevent the scripts failing at all.

wow, they upgraded you from a 7 year old version of perl to a 3.5 year old version? — ysth, Jan 13 '13 at 03:57

score 7 · Answer 1 · edited Jan 12 '13 at 20:19

7

Depending on the amount of flexibility you have when configuring your environment you may want to use Perlbrew.

to maintain an independent Perl installation at a specific version. This can avoid nasty surprises when the system-wide Perl installation changes.

edited Jan 12 '13 at 20:19

Constantinius

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answered Jan 12 '13 at 14:18

Seán Labastille

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Thanks I was just going to add that too, but you beat me. – Joel Berger Jan 12 '13 at 14:19

Joel Berger · Answer 2 · 2013-01-12T14:17:42.227

5

The thing you really should do is ensure that your needed modules are installed in the new installation. Especially for XS (C-level) modules there is no guarantee that they will run on a new version of Perl without recompiling since the core may have changed.

You should make a Makefile.PL or Build.PL which declares the dependencies of your scripts and you company should make it a policy to execute those scripts on server migration.

Finally, yes you can check $^V which is the running Perl. And if you do it inside a BEGIN block it will be executed during startup. In fact you can use local directories for your (pure perl) modules and then point to them using the lib module.

edited Jan 12 '13 at 14:17

answered Jan 12 '13 at 14:09

Joel Berger

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Thanks for the suggestions. Fortunately the modules in question are very small and not C, so I think I've got away with just copying the tree. For the time being, I've added a version number check into my upper level script that does not use the modules so that it can alert me and take other action rather than just letting the lower-level scripts fail. – appleton Jan 12 '13 at 18:36
If the check is in a `BEGIN` block before any `use` statements then it will still be able to take some action even before the `use`-es fail. – Joel Berger Jan 12 '13 at 19:16

score 2 · Answer 3 · answered Jan 12 '13 at 19:41

Why did you move the files at all? Just keep add to PERL5LIB instead.

PERL5LIB=$HOME/perl/lib/perl5/5.10.1:$HOME/perl/lib/perl5/5.8.8

I strongly recommend that you simply use perlbrew to install a build of Perl in your home directory instead of being at your host's mercy.

Perl module version

3 Answers3