CPANM is a handy little tool for quickly getting modules installed. It is a simplified version of CPAN. I like CPANM for quick tasks and it has become one of my main go to tools. I use CPAN, or manually building when I need to do unusual things or CPANM fails.

See the following for all the fun

• http://search.cpan.org/~miyagawa/App-cpanminus-1.7001/bin/cpanm
  

For CentOS 6 and other similar RedHat/Yum systems

• yum install perl-devel
  
• yum install perl-CPAN
  
• curl -L http://cpanmin.us | perl - --sudo App::cpanminus
  
• Wait a few minutes as a lot is going on
  

Example of use

• sudo /usr/local/bin/cpanm CGI
  

To make /usr/local/bin one of your search directories (do this at your own risk)

• Edit ~root/.bash_profile (root is the typical CPANM user unless you install CPANM as a local user)
  
• Append the following to the end of the file or anywhere you like
  
• # Add local bin (mostly for CPANM)
  PATH=$PATH:/usr/local/bin
  

During routine maintenance I noticed that CPAN was failing operate properly and giving me an error I had not seen before. (updated 2014-02-25 with related errors seen on another system)

• Undefined subroutine &Compress::Zlib::gzopen called at /usr/lib/perl5/5.8.8/CPAN.pm line 5721
• Use of uninitialized value in concatenation (.) or string at /usr/lib64/perl5/5.8.8/x86_64-linux-thread-multi/Scalar/Util.pm line 30.

(Update: The error was also seen on CentoS 5.5 while installing IO::Socket::SSL via CPAN and the fix below resolved this problem)

This may have happened when I installed awstats on my CentOS5 VPS. It grabbed a yum for Compress::Zlib. I suspect something odd happened and and now CPAN fails. I lack the time right now to track this down for sure and this is a production system so doing a full YUM update is something I need to avoid for a bit.

The fix is to manually bring things into compliance. Using the YUM to obtain the perl-Package-Name would probably be a good Idea but they do not appear to be quite right. The following is what I ended up doing although the path to get here felt like 2 steps forward 1 back. All files were retrieved manually from www.cpan.org via wget (use CPAN search and use the package name as the term) and then the standard Perl mantra; perl Makefile.PL, make, make test, make install. The order of installs is important! I determined the order by examining the warnings from perl Makefile.PL and make test.

• Scalar::Util — required because IO:Compress failed test due to XS not being in my Scalar package
• Compress::Raw::Bzip2
• Compress::Raw::Zlib — per Compress::Zlib makefile operation
• IO::Compress - as of 2014-02 this includes Base and Gzip, prior to that you may need to download those separate: IO::Compress::Base and IO::Compress::Gzip (Note: This takes a long time for tests).

• Compress::Zlib — the faulty package
  

After this was done all was good and CPAN now works!