I get this warning when using cpan for the first time: $ cpan CPAN.pm requires configuration, but most of it can be done automatically. If you answer 'no' below, you will enter an interactive dialog for each configuration option instead. Would you like to configure as much as possible automatically? [yes] Use of uninitialized value $what in concatenation (.) or string at /usr/share/perl/5.20/App/Cpan.pm line 554, <STDIN> line 1. <install_help> Warning: You do not have write permission for Perl library directories. ...