The first time you use the Perl module CPAN, a script is executed in order to properly configure several options (like the location of tar, gzip and unzip files, the cache size for the build directory, etc).

If you want to modify these configuration options at a later time, you can do it in 2 ways:

- Manually, modifying the configuration files

You can either modify the user-specific file (usually ~/.cpan/CPAN/MyConfig.pm) or the system-wide configuration file (stored somewhere in the perl module directory tree, look for a directory named CPAN that holds a file named Config.pm)

- Automatically, using the CPAN module

To do this, execute the following:

perl -MCPAN -e shell

When you're in the cpan shell, execute:

cpan> o conf init ⇐ For the life of me I can never remember this!!

Thanks to Original Post at http://www.perlhowto.com/reconfigure_cpan_module_preferences