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App::cpanminus - get, unpack, build and install modules from CPAN


cpanm Module
cpanm MIYAGAWA/Plack-1.0000.tar.gz
cpanm ~/mydists/MyCompany-Framework-1.0.tar.gz
cpanm --interactive Task::Kensho

Run cpanm -h for more options.


cpanminus is a script to get, unpack, build and install modules from CPAN.

Its catch? Deps-free, zero-conf, standalone but maintainable and extensible with plugins and shell scripting friendly. In the runtime it only requires 10MB of RAM.


If you have git,

git clone git://
cd cpanminus
perl Makefile.PL
make install


cd ~/bin
chmod +x cpanm
# edit shebang if you don't have /usr/bin/env


perl 5.8 or later (Actually I believe it works with pre 5.8 too but haven't tested).

LWP or 'wget' to get files over HTTP.

'tar' executable (if GNU tar, version 1.22 or later) or Archive::Tar to unpack files.

C compiler, if you want to build XS modules.

And optionally:

make, if you want to more reliably install MakeMaker based modules

Module::Build (core in 5.10) if you want to install MakeMaker based modules without 'make'


WARNING: plugin API is not stable so this feature is turned off by default for now. To enable plugins you have to be savvy enough to look at the build.log or read the source code to see how :)

cpanminus core is a tiny 600 lines of code (with some embedded utilities and documents) but can be extended by writing plugins. Plugins are flat perl script that should be placed inside ~/.cpanm/plugins. See plugins/ directory in the git repository for the list of available and sample plugins.


Another CPAN installer?

OK, the first motivation was this: CPAN shell gets OOM (or swaps heavily and gets really slow) on Slicehost/linode's most affordable plan with only 256MB RAM. Should I pay more to install perl modules from CPAN? I don't think so.

But why a new client?

First of all, I don't have an intention to dis CPAN or CPANPLUS developers. Don't get me wrong. They're great tools and I've been using it for literally years (Oh, you know how many modules I have on CPAN, right?) I really respect their efforts of maintaining the most important tools in the CPAN toolchain ecosystem.

However, I've learned that for less experienced users (mostly from outside the Perl community), or even really experienced Perl developers who knows how to shoot in their feet, setting up the CPAN toolchain could often feel really yak shaving, especially when all they want to do is just install some modules and start writing some perl code.

In particular, here are the few issues I've been observing:

Too many questions. No sane defaults. Normal user doesn't (and shouldn't have to) know what's the right answer for the question Parameters for the 'perl Build.PL' command? []

Very noisy output by default.

Fetches and rebuilds indexes like every day and takes like a minute

... and hogs 200MB of memory and thrashes/OOMs on my 256MB VPS

And cpanminus is designed to be very quiet (but logs all output to ~/.cpanm/build.log), pick whatever the sanest defaults as possible without asking any questions to just work.

Note that most of these problems with existing tools are rare, or are just overstated and might be already fixed issues, or can be configured to work nicer. For instance the latest dev release has a much better FirstTime experience than previously.

And I know there's a reason for them to have many options and questions, since they're meant to work everywhere for everybody.

And yes, of course I should have contributed back to CPAN/CPANPLUS instead of writing a new client, but is nearly impossible to maintain (that's why CPANPLUS was born, right?) and CPANPLUS is a huge beast for me to start working on.

Are you on drugs?

Yeah, I think my brain has been damaged since I looked at PyPI, gemcutter, pip and rip. They're quite nice and I really wanted something as nice for CPAN which I love.

How does this thing work?

So, imagine you don't have CPAN or CPANPLUS. What you're going to do is to search the module on the CPAN search site, download a tarball, unpack it and then run perl Makefile.PL (or perl Build.PL). If the module has dependencies you probably have to recurively resolve those dependencies by hand before doing so. And then run the unit tests and make install (or ./Build install).

This script just automates that.

Zero-conf? How does this module get/parse/update the CPAN index?

It scrapes the site Yes, it's horrible and fragile. I hope (and have already talked to) QA/toolchain people for building a queriable CPAN DB website so I can stop scraping.

Fetched files are unpacked in ~/.cpanm but you can configure with PERL_CPANM_HOME environment variable.

Where does this install modules to?

It installs to wherever ExtUtils::MakeMaker and Module::Build are configured to (i.e. via PERL_MM_OPT and MODULEBUILDRC). So if you use local::lib then it installs to your local perl5 directory. Otherwise it installs to siteperl directory.

cpanminus at a boot time checks whether you configured local::lib setup, or have the permission to install modules to the sitelib directory, and warns you otherwise so that you need to run cpanm command as root, or run with --sudo option to auto sudo when running the install command.

Does this really work?

I tested installing MojoMojo, Task::Kensho, KiokuDB, Catalyst, Jifty and Plack using cpanminus and the installations including dependencies were mostly successful. So multiplies of half of CPAN behave really nicely and appear to work.

However, there are some distributions that will miserably fail, because of the nasty edge cases (funky archive formats, naughty tarball that extracts to the current directory, META.yml that is outdated and cannot be resurrected, Bundle:: modules, circular dependencies etc.) while CPAN and CPANPLUS can possibly handle them.

Well in other words, cpanminus is aimed to work against 99% of modules on CPAN for 99% of people. It may not be perfect, but it should just work in most cases.

That sounds fantastic. Should I switch to this from CPAN(PLUS)?

If you've got CPAN or CPANPLUS working then you may keep using CPAN or CPANPLUS in the longer term, but I just hope this can be a quite handy alternative to them for people in other situations. And apparently, many people love (at least the idea of) this software :)


Copyright 2010- Tatsuhiko Miyagawa

Parse::CPAN::Meta, included in this script, is Copyright 2006-2009 Adam Kennedy


Same as Perl.


Patches contributed by: Goro Fuji, Kazuhiro Osawa, Tokuhiro Matsuno, Kenichi Ishigaki, Ian Wells, Pedro Melo, Masayoshi Sekimura and Matt S Trout.

Feedbacks sent by: Jesse Vincent, David Golden, Chris Williams, Adam Kennedy, J. Shirley, Chris Prather, Jesse Luehrs, Marcus Ramberg, Shawn M Moore, chocolateboy, Ingy dot Net, Chirs Nehren, Jonathan Rockway and Leon Brocard.



This software is provided "as-is," without any express or implied warranty. In no event shall the author be held liable for any damages arising from the use of the software.