I really dislike having to install perl modules locally. But sometimes that’s the set of cards I get dealt. And in all honesty, once it’s properly set up in an account, it’s easy to add on any others at a later date. So. I generally start with a local perl directory, in $HOME/perl, to keep things tidy. Otherwise I wind up with a more generic bin and lib sitting out there, and there’s lots that use bin & lib that have nothing to do with perl.

I add env variables:

if [ -d $HOME/perl/lib/perl5 ]; then
        PERL5LIB=${PERL5LIB:+$PERL5LIB:}$HOME/perl/lib/perl5
fi
MANPATH=${MANPATH:+$MANPATH:}$HOME/perl/share/man
export MANPATH PERL5LIB

(or if you prefer csh style — which I do, but I haven’t bothered to switch these bash shells around yet — I may, if I get irritated enough)

setenv PERL5LIB      $PERL5LIB:$HOME/perl/lib/perl5
setenv MANPATH     $MANPATH:$HOME/perl/share    

You can use printenv in most shells to double check the settings and make sure they “stuck”.

There really doesn’t seem to be any one place that combines all the info I use for a local install. I usually start out with this one which is almost complete but it leaves out salient details such as exactly how to start up cpan (which I always forget, it has such forgettable syntax) and doesn’t really contain tips for troubleshooting (there’s always troubleshooting).

However, it provides a perfect MyConfig.pm file to get started with, so I copy that into the ~/.cpan/CPAN/MyConfig.pm and follow the instructions it has in the comment section at the top. After the localizing alterations, I can run perl -c MyConfig.pm in order to make sure I haven’t done something boneheaded.

Now I’m ready to rock and roll. Get into cpan via perl -MCPAN -e 'shell' and now I can start installing. The help file I listed before suggests checking the changes I make to MyConfig.pm via a make on Text::Autoformat. I don’t really bother anymore but it’s a handy way to check that the variables are all correct.

Let’s say I want to install Flickr’s API. So I go with install Flickr::API. It will ask me some questions. What I have found out about CPAN is that most of the time (as in 99% of the time), the default is a perfectly good way to go when it asks questions. Quite often when I install something, it will suggest other things that should be installed or updated, etc. I just go with the flow on all that.

When I nibble around this article you’ll see more tips and such on unprivileged perl installs. Obviously installing your entire local copy of perl isn’t the way to go for the most part (and neither am I actually trying to install Bugzilla, at least not in this little essay), and they discuss a slightly different way of setting up the MyConfig.pm file, but there’s other goodies such as force install which I can try if I get nasty messages after attempting a plain install. Also what frequently helps me is to try installing the noted dependency packages on their own. Take the Flickr::API — it also wants XML:: Parser::Lite::Tree:: XPath and will inform me of that while installing the Flickr stuff. And sometimes it will take care of it, and sometimes it won’t; doing a separate install on that often works.

The last bugaboo I generally wind up dealing with, especially since I mostly write perl for cgi scripts is the transition from running on the command line to calling it from a web page. All the previously mentioned steps get the perl working on the command line, but then it can still turn into a big ol’ Internal Server Error mess when I try to go online.

The problem is, of course, that the http client isn’t accessing my pretty MANPATH and PERL5LIB paths for the extra info. This is where tweaking the @INC array helps: I can be all perl hacky and do something like BEGIN{unshift @INC, "$HOME/perl/lib/perl5"} (note that $HOME itself won’t actually work here, I use it for shorthand notation — replace this with the full value of $HOME in this case). But I just discovered this tidbit when googling and trying the use "$HOME/perl/lib/perl5"; worked like a charm! I’ve posted this previously only at another location: the flickr slideshow. Because www.sclrr.org is on a different server than is www.io.com/~sclrr, I had to re-install the perl libraries, and find a different solution to the path problem.