How do I get a list of installed CPAN modules?

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

Try the following command

instmodsh

With l you will List all installed modules.

From man page:

A shell to examine installed modules.
A little interface to ExtUtils::Installed to examine installed modules, validate your packlists and even create a tarball from an installed module.

I like to use the CPAN 'r' command for this. You can get into the CPAN shell with the old style:

sudo perl -MCPAN -e shell

or, on most newer systems, there is a 'cpan' command, so this command will get you to the shell:

sudo cpan

(You typically have to use 'sudo' to run it as root, or use 'su -' to become root before you run it, unless you have cpan set up to let you run it as a normal user, but install as root. If you don't have root on this machine, you can still use the CPAN shell to find out this information, but you won't be able to install modules, and you may have to go through a bit of setup the first time you run it.)

Then, once you're in the cpan shell, you can use the 'r' command to report all installed modules and their versions. So, at the "cpan>" prompt, type 'r'. This will list all installed modules and their versions. Use '?' to get some more help.

Here's a really hacky way to do it in *nix, you'll get some stuff you don't really care about (ie: warnings::register etc), but it should give you a list of every .pm file that's accessible via perl.

for my $path (@INC) {
    my @list = `ls -R $path/**/*.pm`;
    for (@list) {
        s/$path\///g;
        s/\//::/g;
        s/\.pm$//g;
        print;
    }
}

Here's a Perl one-liner that will print out a list of installed modules:

perl -MExtUtils::Installed -MData::Dumper -e  'my ($inst) = ExtUtils::Installed->new(); print Dumper($inst->modules());'

Just make sure you have Data::Dumper installed.