How do I get a list of installed CPAN modules?

perldoc -q installed

claims that cpan -l will do the trick, however it's not working for me. The other option:

cpan -a

does spit out a nice list of installed packages and has the nice side effect of writing them to a file.

$ for M in `perldoc -t perllocal|grep Module |sed -e 's/^.*" //'`; do V=`perldoc -t perllocal|awk "/$M/{y=1;next}y" |grep VERSION |head -n 1`; printf "%30s %s\n" "$M" "$V"; done |sort
              Class::Inspector     *   "VERSION: 1.28"
                    Crypt::CBC     *   "VERSION: 2.33"
               Crypt::Rijndael     *   "VERSION: 1.11"
                    Data::Dump     *   "VERSION: 1.22"
                   DBD::Oracle     *   "VERSION: 1.68"
                           DBI     *   "VERSION: 1.630"
                   Digest::SHA     *   "VERSION: 5.92"
           ExtUtils::MakeMaker     *   "VERSION: 6.84"
                       install     *   "VERSION: 6.84"
               IO::SessionData     *   "VERSION: 1.03"
               IO::Socket::SSL     *   "VERSION: 2.016"
                          JSON     *   "VERSION: 2.90"
                  MIME::Base64     *   "VERSION: 3.14"
                  MIME::Base64     *   "VERSION: 3.14"
                   Mozilla::CA     *   "VERSION: 20141217"
                   Net::SSLeay     *   "VERSION: 1.68"
                        parent     *   "VERSION: 0.228"
                  REST::Client     *   "VERSION: 271"
                    SOAP::Lite     *   "VERSION: 1.08"
                  Task::Weaken     *   "VERSION: 1.04"
                 Term::ReadKey     *   "VERSION: 2.31"
                Test::Manifest     *   "VERSION: 1.23"
                  Test::Simple     *   "VERSION: 1.001002"
                  Text::CSV_XS     *   "VERSION: 1.16"
                     Try::Tiny     *   "VERSION: 0.22"
                   XML::LibXML     *   "VERSION: 2.0108"
         XML::NamespaceSupport     *   "VERSION: 1.11"
                XML::SAX::Base     *   "VERSION: 1.08"

This is answered in the Perl FAQ, the answer which can be quickly found with perldoc -q installed. In short, it comes down to using ExtUtils::Installed or using File::Find, variants of both of which have been covered previously in this thread.

You can also find the FAQ entry "How do I find which modules are installed on my system?" in perlfaq3. You can see a list of all FAQ answers by looking in perlfaq

perldoc perllocal

Edit: There's a (little) more info about it in the CPAN FAQ