how-to check that perl modules are installed

      use strict ; use warnings ; 

      use 5.10.0 ; 

      use ExtUtils::Installed;

      #  quick and dirty check for prerequisites perl modules:

      #  courtesy of:http://stackoverflow.com/a/9340304/65706

      #  if you have a calling bash script call by :

      #  perl "/path/to/isg_pub_preq_cheker.pl"

      #  export ret=$?

      #  test $ret -ne 0 && doExit 1 "[FATAL] perl modules not found!!!"

      # check that all the required modules are installed

      my ( $ret , $msg ) = doCheckRequiredModules();

      unless ( $ret == 0 ) {

         print "$msg" ; 

         # give some time for the user to react

         print "printing all installed modules :" ; 

         my $c = 9 ; 

         for ( my $i=0;$i<=$c;$i++){

            print ( ( $c-$i) . '.') ;  

            sleep 1 ; 

         }

         print "\n" ; 

         doListAllInstalledModules();  

         print "\n" ; 

      }

      exit(0);

      sub doListAllInstalledModules {

         my $instmod = ExtUtils::Installed->new();

          foreach my $module ($instmod->modules()) {

            my $version = $instmod->version($module) || "???"; 

             print "found module:$module -- v$version\n"; 

            }

      }

      #eof sub

      sub doCheckRequiredModules {

         my @modules = qw(

            Test::More

            Test::Deep

            CPAN::SQLite

            File::Copy::Recursive

            HTML::TreeBuilder

            HTML::TreeBuilder::XPath

            HTML::TableExtract

            HTML::ElementTable

            Spreadsheet::XLSX

            IO::HTML

            Regexp::Common

            Test::More

            Spiffy

            Filter::Util::Call

            Algorithm::Diff

            Text::Diff

            Test::Base

            Test::CPAN::Meta::YAML

            Test::YAML::Valid  

            Test::YAML::Meta

            Test::YAML

            YAML::Any

            Data::Printer

            LWP

            Text::Template

            HTML::Template

            Module::Signature

            Taint

            ExtUtils::Installed

         );

         for(@modules) {

             eval "use $_";

             if ($@) {

               my $msg = "\n\n\n [FATAL] did not found the following perl module: $_ " ; 

               $msg .= "\n you must install it in the shell by running the following commands:" ; 

               # if the user knows already the difference between the running the cmd 

               # with sudo or he / she probably knows already how-to install perl modules

               $msg .= "\n" . 'as a start configure the cpan to install dependancies first' . "\n" ; 

               $msg .= "\n" . 'perl -MCPAN -e \'my $c = "CPAN::HandleConfig"; $c->load(doit => 1, autoconfig => 1); $c->edit(prerequisites_policy => "follow"); $c->edit(build_requires_install_policy => "yes"); $c->commit\'' . "\n" ; 

               $msg .= "\n" . 'than install by :' . "\n" ; 

               $msg .= "\n sudo perl -MCPAN -e 'install $_'\n\n\n" ; 

               $msg .= "\n if you seem to be stuck in circular reference kind of loop try even :\n" ; 

               $msg .= "\n sudo perl -MCPAN -e 'CPAN::Shell->force(qw( install $_));'\n" ; 

               $msg .= "\n sudo perl -MCPAN -e 'CPAN::Shell->force(qw( install $_));'\n" ; 

               $msg .= "\n You may end-up now with Ctrl + C \n\n\n" ; 

               return ( 1, "$msg")  if $@;

             } else {

                 say "[INFO ] == ok == check for prerequisite perl module : $_";

             }

         }

         #eof foreach module

         return ( 0 , "all required modules found" ) ;   

      }

      #eof sub