Recipe 12.23 Program: Finding Versions and Descriptions of Installed Modules

Perl comes with many modules included standard. Even more can be found on CPAN. The following program prints out the names, versions, and descriptions of all modules installed on your system. It uses standard modules like File::Find and includes several techniques described in this chapter.

To run it, type:

% pmdesc

It prints a list of modules and their descriptions:

FileHandle (2.00) - supply object methods for filehandles
IO::File (1.06021) - supply object methods for filehandles
IO::Select (1.10) - OO interface to the select system call
IO::Socket (1.1603) - Object interface to socket communications
...

With the -v flag, pmdesc provides the names of the directories the files are in:

% pmdesc -v

<<<Modules from /usr/lib/perl5/i686-linux/5.00404>>>

FileHandle (2.00) - supply object methods for filehandles
    ...

The -w flag warns if a module doesn't come with a pod description, and -s sorts the module list within each directory.

The program is given in Example 12-3.

Example 12-3. pmdesc

  #!/usr/bin/perl -w
  # pmdesc - describe pm files
  # tchrist@perl.com
  
  use strict;
  use File::Find      qw(find);
  use Getopt::Std     qw(getopts);
  use Carp;
  
  use vars (
      q!$opt_v!,              # give debug info
      q!$opt_w!,              # warn about missing descs on modules
      q!$opt_a!,              # include relative paths
      q!$opt_s!,              # sort output within each directory
  );
  
  $| = 1;
  
  getopts("wvas")             or die "bad usage";
  
  @ARGV = @INC unless @ARGV;
  
  # Globals.  wish I didn't really have to do this.
  use vars (
      q!$Start_Dir!,          # The top directory find was called with
      q!%Future!,             # topdirs find will handle later
  );
  
  my $Module;
  
  # install an output filter to sort my module list, if wanted.
  if ($opt_s) {
      if (open(ME, "-|")) {
          $/ = "";
          while (<ME>) {
              chomp;
              print join("\n", sort split /\n/), "\n";
          }
          exit;
      }
  }
  
  MAIN: {
      my %visited;
      my ($dev,$ino);
  
      @Future{@ARGV} = (1) x @ARGV;
  
      foreach $Start_Dir (@ARGV) {
          delete $Future{$Start_Dir};
  
          print "\n << Modules from $Start_Dir>>\n\n"
              if $opt_v;
  
          next unless ($dev,$ino) = stat($Start_Dir);
          next if $visited{$dev,$ino}++;
          next unless $opt_a || $Start_Dir =~ m!^/!;
  
          find(\&wanted, $Start_Dir);
      }
      exit;
  }
  
  # calculate module name from file and directory
  sub modname {
      local $_ = $File::Find::name;
  
      if (index($_, $Start_Dir . "/") =  = 0) {
          substr($_, 0, 1+length($Start_Dir)) = "";
      }
  
      s { /              }    {::}gx;
      s { \.p(m|od)$     }    {  }x;
  
      return $_;
  }
  
  # decide if this is a module we want
  sub wanted {
      if ( $Future{$File::Find::name} ) {
          warn "\t(Skipping $File::Find::name, qui venit in futuro.)\n"
              if 0 and $opt_v;
          $File::Find::prune = 1;
          return;
      }
      return unless /\.pm$/ && -f;
      $Module = &modname;
      # skip obnoxious modules
      if ($Module =~ /^CPAN(\Z|::)/) {
          warn("$Module -- skipping because it misbehaves\n");
          return;
      }
  
      my    $file = $_;
  
      unless (open(POD, "<", $file)) {
          warn "\tcannot open $file: $!";
              # if $opt_w;
          return 0;
      }
  
      $: = " -:";
  
      local $/ = "";
      local $_;
      while (<POD>) {
          if (/=head\d\s+NAME/) {
              chomp($_ = <POD>);
              s/^.*?-\s+//s;
              s/\n/ /g;
              #write;
              my $v;
              if (defined ($v = getversion($Module))) {
                  print "$Module ($v) ";
              } else {
                  print "$Module ";
              }
              print "- $_\n";
              return 1;
          }
      }
  
      warn "\t(MISSING DESC FOR $File::Find::name)\n"
          if $opt_w;
  
      return 0;
  }
  
  # run Perl to load the module and print its verson number, redirecting
  # errors to /dev/null
  sub getversion {
      my $mod = shift;
  
      my $vers = `$^X -m$mod -e 'print \$${mod}::VERSION' 2>/dev/null`;
      $vers =~ s/^\s*(.*?)\s*$/$1/; # remove stray whitespace
      return ($vers || undef);
  }
  
  format = ^<<<<<<<<<<<<<<<<<~~^<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
  $Module,        $_
  .

This can also be accomplished through the backend programmer interface in the CPANPLUS module, if you have it installed. This program displays information on all available modules (the -X option is to silence any warnings about invalid paths or version numbers):

#!/usr/bin/perl -X

use CPANPLUS::Backend;
use Data::Dumper;

$cp = CPANPLUS::Backend->new;
$installed = $cp->installed->rv;          # fetch list of installed mods

foreach my $module (sort keys %$installed) {
  # get the module's information
  $info = $cp->details(modules => [$module])->rv->{$module};
  # display the fields we care about
  printf("%-35.35s %44.44s\n", $module, $info->{Description});
}

When run, it outputs a table like this:

Algorithm::Cluster                  Perl extension for the C clustering library
Algorithm::NaiveBayes                                                None given
AnyDBM_File                            Uses first available *_File module above
Apache                                       Interface to the Apache server API
Apache::AuthDBI                                                      None given
Apache::Connection                           Inteface to Apache conn_rec struct