How can I check if a Perl module is installed on m

Question

I tried to check if XML::Simple is installed in my system or not.

perl -e 'while (<@INC>) { while (<$_/*.pm>) { print "$_\n"; } }'

The above one-liner was used for listing all modules installed in my system. However, it is not listing XML modules.

However, the following executes fine.

perl -e "use XML::Simple "

What might be the issue?

Answer 1

If you want to quickly check if a module is installed (at least on Unix systems, with Bash as shell), add this to your .bashrc file:

alias modver="perl -e\"eval qq{use \\\$ARGV[0];\\\\\\\$v=\\\\\\\$\\\${ARGV[0]}::VERSION;};\ print\\\$@?qq{No module found\\n}:\\\$v?qq{Version \\\$v\\n}:qq{Found.\\n};\"\$1"

Then you can:

=> modver XML::Simple
No module found

=> modver DBI
Version 1.607

Answer 2

You can check for a module's installation path by:

perldoc -l XML::Simple

The problem with your one-liner is that, it is not recursively traversing directories/sub-directories. Hence, you get only pragmatic module names as output.

Answer 3

Quick and dirty:

$ perl -MXML::Simple -e 1

Answer 4

$ perl -MXML::Simple -le 'print $INC{"XML/Simple.pm"}'

From the perlvar entry on %INC:

• %INC

The hash %INC contains entries for each filename included via the do, require, or use operators. The key is the filename you specified (with module names converted to pathnames), and the value is the location of the file found. The require operator uses this hash to determine whether a particular file has already been included.

If the file was loaded via a hook (e.g. a subroutine reference, see require for a description of these hooks), this hook is by default inserted into %INC in place of a filename. Note, however, that the hook may have set the %INC entry by itself to provide some more specific info.