how to determine whether a module is installed or not?

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

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Re: how to determine whether a module is installed or not? by tilly (Archbishop) on Dec 28, 2010 at 05:46 UTC
Something like this (untested and I am rusty): `eval {require Text::LevenshteinXS}; if ($@) { eval {require Text::Levenshtein}; else { require "Levenshtein.lib"; } }` [download]	[reply] [d/l]
Re^2: how to determine whether a module is installed or not? by Anonymous Monk on Dec 28, 2010 at 05:58 UTC
Thank you very much.	[reply]
Re: how to determine whether a module is installed or not? by GrandFather (Saint) on Dec 28, 2010 at 06:01 UTC
Something like: `if (eval {require 'Text/LevenshteinXS.pm'}) { Text::LevenshteinXS::import('distance'); } elsif (eval {require 'Text/Levenshtein.pm'}) { Text::Levenshtein::import('distance'); } else { *distance = \&myDistanceSub; }` [download] True laziness is hard work	[reply] [d/l]
Re^2: how to determine whether a module is installed or not? by slayedbylucifer (Scribe) on Dec 28, 2010 at 06:50 UTC
I found this on Google. this perl oneliner will list all the installed modules on your system (Linux). then you can grep for whatever module your are looking for. `perl -MFile::Find=find -MFile::Spec::Functions -Tlwe 'find { wanted => + sub { print canonpath $_ if /\.pm\z/ }, no_chdir => 1 }, @INC'` [download]	[reply] [d/l]
Re^3: how to determine whether a module is installed or not? by tilly (Archbishop) on Dec 28, 2010 at 07:29 UTC
That is an extremely inefficient solution.	[reply]
Re: how to determine whether a module is installed or not? by planetscape (Chancellor) on Dec 28, 2010 at 09:40 UTC
See also (in no particular order): whatinstalled.pl offsite whatdists.pl offsite Find installed Perl modules matching a regular expression Re: Listing all of the perl modules installed modlist.pl offsite Module Installation Verifier HTH, planetscape	[reply]
Re^2: how to determine whether a module is installed or not? by Marshall (Canon) on Dec 29, 2010 at 21:41 UTC
I really liked your list! This is ActiveState specific for their ppm utility, but for those who have ActiveState, it is handy: $prompt>ppm profile save [my_config_file] (with no file, ouput goes to stdout) $prompt>ppm profile restore my_config_file The save option makes an XML file with lines like this: <SOFTPKG NAME="Text-LevenshteinXS" VERSION="0.03"/> This file also contains the ppm repositories that I have configured - not everything is at the main ActiveState repository. So if I want to "clone" my installation on another computer or for some reason do a complete re-installation on my own computer, I use the "save" command to a file. Then uninstall Perl, wipe out my Perl directory, re-install ActiveState Perl and then run the "restore" option to get all the packages re-installed. I just walked a friend through this last week and he said that it worked fine. I think the OP wanted to know what is going on at run time on some other "unknown system", but if we are talking about utilities, I think this is a good one for AS users and I have recent experience that it does indeed "work as advertised".	[reply]
Re^3: how to determine whether a module is installed or not? by planetscape (Chancellor) on Dec 30, 2010 at 17:21 UTC
I think the OP wanted to know what is going on at run time on some other "unknown system" I think you are right, but I wasn't quite sure when I posted my reply, and thought it might prove useful to future searchers who come upon the thread. Thanks for your addition.++ HTH, planetscape	[reply]
Re: how to determine whether a module is installed or not? by samarzone (Pilgrim) on Dec 28, 2010 at 08:30 UTC
`eval`uating (as given in above solutions) is the correct solution at run time but if you want a list of installed modules for a quick reference in future, there is a perl script '`instmodsh`' which is shipped with Perl. (At least I have it installed with perl-5.8.8-18.el5 :) ). In my system it is installed at path `/usr/bin/instmodsh` so I can run it directly as a shell command. -- Regards - Samar	[reply] [d/l] [select]
Re: how to determine whether a module is installed or not? by k_manimuthu (Monk) on Dec 28, 2010 at 08:50 UTC
A command line option `perl -MModule::Name -e l` [download] If the "Module::Name" installed it doesn't show the error. Otherwise it shows the error.	[reply] [d/l]
Re: how to determine whether a module is installed or not? by ajguitarmaniac (Sexton) on Dec 28, 2010 at 14:26 UTC
Checking for similar posts before posting really paid off! I was just about to post the exact same question (but I was looking to find the availability of another module). Thank you monks!	[reply]
Re: how to determine whether a module is installed or not? by JavaFan (Canon) on Dec 28, 2010 at 16:36 UTC
`eval {require "Text::LevenshteinXS"; Text::LevenshteinXS->import; 1} o +r eval {require "Text::Levenshtein"; Text::Levenshtein->import; 1} or do {require "Levenshtein.lib"; Levenshtein->import};` [download]	[reply] [d/l]