perl -MCPAN -e shell;
Batch mode:
use CPAN;
autobundle, clean, install, make, recompile, test
Modules are fetched from one or more of the mirrored CPAN (Comprehensive Perl Archive Network) sites and unpacked in a dedicated directory.
The CPAN module also supports the concept of named and versioned 'bundles' of modules. Bundles simplify the handling of sets of related modules. See BUNDLES below.
The package contains a session manager and a cache manager. There is no status retained between sessions. The session manager keeps track of what has been fetched, built and installed in the current session. The cache manager keeps track of the disk space occupied by the make processes and deletes excess space according to a simple FIFO mechanism.
All methods provided are accessible in a programmer style and in an interactive shell style.
perl -MCPAN -e shell
which puts you into a readline interface. You will have most fun if you install Term::ReadKey and Term::ReadLine to enjoy both history and completion.
Once you are on the command line, type 'h' and the rest should be self-explanatory.
The most common uses of the interactive modes are
Arguments you pass to these commands are either strings matching exact the identification string of an object or regular expressions that are then matched case-insensitively against various attributes of the objects. The parser recognizes a regualar expression only if you enclose it between two slashes.
The principle is that the number of found objects influences how an item is displayed. If the search finds one item, we display the result of object->as_string, but if we find more than one, we display each as object->as_glimpse. E.g.
    cpan> a ANDK
    Author id = ANDK
        EMAIL        a.koenig@franz.ww.TU-Berlin.DE
        FULLNAME     Andreas König
    cpan> a /andk/
    Author id = ANDK
        EMAIL        a.koenig@franz.ww.TU-Berlin.DE
        FULLNAME     Andreas König
    cpan> a /and.*rt/
    Author          ANDYD (Andy Dougherty)
    Author          MERLYN (Randal L. Schwartz)
Any make, test, and readme are run unconditionally. A
install <distribution_file>
also is run unconditionally. But for
install <module>
CPAN checks if an install is actually needed for it and prints Foo up to date in case the module doesn&39;t need to be updated.
CPAN also keeps track of what it has done within the current session and doesn&39;t try to build a package a second time regardless if it succeeded or not. The force command takes as first argument the method to invoke (currently: make, test, or install) and executes the command from scratch.
Example:
    cpan> install OpenGL
    OpenGL is up to date.
    cpan> force install OpenGL
    Running make
    OpenGL-0.4/
    OpenGL-0.4/COPYRIGHT
    [...]
Look gets and untars (if not yet done) the distribution file, changes to the
appropriate directory and opens a subshell process in that directory.
$CPAN::Config->{cpan_home}/Bundle directory. The file contains a list of all modules that are both available from 
CPAN and currently installed within 
@INC. The name of the bundle file is based on the current date and a counter.
recompile() is a very special command in that it takes no argument and runs the make/test/install cycle with brute force over all installed dynamically loadable extensions (aka 
XS modules) with 'force' in effect. Primary purpose of this command is to finish a network installation. Imagine, you have a common source tree for two different architectures. You decide to do a completely independent fresh installation. You start on one architecture with the help of a Bundle file produced earlier. 
CPAN installs the whole Bundle for you, but when you try to repeat the job on the second architecture, 
CPAN responds with a
 "Foo up to date" message for all modules. So you will be glad to run recompile in the second
architecture and you&39;re done.
Another popular use for recompile is to act as a rescue in case your perl breaks binary compatibility. If one of the modules that CPAN uses is in turn depending on binary compatibility (so you cannot run CPAN commands), then you should try the CPAN::Nox module for recovery.
Namespace Class
   words containing a "/" (slash)      Distribution
    words starting with Bundle::          Bundle
          everything else            Module or Author
Modules know their associated Distribution objects. They always refer to the most recent official release. Developers may mark their releases as unstable development versions (by inserting an underbar into the visible version number), so not always is the default distribution for a given module the really hottest and newest. If a module Foo circulates on CPAN in both version 1.23 and 1.23_90, CPAN.pm offers a convenient way to install version 1.23 by saying
install Foo
This would install the complete distribution file (say BAR/Foo-1.23.tar.gz) with all accompanying material in there. But if you would like to install version 1.23_90, you need to know where the distribution file resides on CPAN relative to the authors/id/ directory. If the author is BAR, this might be BAR/Foo-1.23_90.tar.gz, so he would have to say
install BAR/Foo-1.23_90.tar.gz
The first example will be driven by an object of the class CPAN::Module, the second by an object of class Distribution.
CPAN::Shell->install(...)) and as functions in the calling package (install(...)).
There's currently only one class that has a stable interface, CPAN::Shell. All commands that are available in the 
CPAN shell are methods of the class CPAN::Shell. Each of the commands that produce listings of modules (
r, autobundle, u) returns a list of the IDs of all modules within the list.
CPAN::Shell->expand("Module",@things) method. Expand returns a list of CPAN::Module objects according to the @things arguments given. In scalar context it only returns the first element of the
list.
    # install everything that is outdated on my disk:
    perl -MCPAN -e 'CPAN::Shell->install(CPAN::Shell->r)'
    # install my favorite programs if necessary:
    for $mod (qw(Net::FTP MD5 Data::Dumper)){
        my $obj = CPAN::Shell->expand('Module',$mod);
        $obj->install;
    }
    # list all modules on my disk that have no VERSION number
    for $mod (CPAN::Shell->expand("Module","/./")){
        next unless $mod->inst_file;
        next if $mod->inst_version;
        print "No VERSION in ", $mod->id, "\n";
    }
build_dir as soon as the size of all directories there gets bigger than $CPAN::Config->{build_cache} (in 
MB). The contents of this cache may be used for later re-installations that you intend to do manually, but will never be trusted by 
CPAN itself. This is due to the fact that the user might use these directories for building modules on different architectures.
There is another directory ($CPAN::Config->{keep_source_where}) where the original distribution files are kept. This directory is not covered by the cache manager and must be controlled by the user. If you choose to have the same directory as build_dir and as keep_source_where directory, then your sources will be deleted with the same fifo mechanism.
It starts like a perl module with a package declaration and a $VERSION variable. After that the pod section looks like any other pod with the only difference, that one special pod section exists starting with (verbatim):
=head1 CONTENTS
In this pod section each line obeys the format
Module_Name [Version_String] [- optional text]
The only required part is the first field, the name of a module (eg. Foo::Bar, ie. not the name of the distribution file). The rest of the line is optional. The comment part is delimited by a dash just as in the man page header.
The distribution of a bundle should follow the same convention as other distributions.
Bundles are treated specially in the 
CPAN package. If you say 'install Bundle::Tkkit' (assuming such a bundle exists), 
CPAN will install all the modules in the 
CONTENTS section of the pod. You can install your own Bundles locally by placing a conformant Bundle file somewhere into your @INC path. The autobundle() command which is available in the shell interface does that for you by including all currently installed modules in a snapshot bundle file.
There is a meaningless Bundle::Demo available on CPAN. Try to install it, it usually does no harm, just demonstrates what the Bundle interface looks like.
ftp:.
If you have neither Net::FTP nor LWP, there is a fallback mechanism implemented for an external ftp command or for an external lynx command.
This module presumes that all packages on CPAN
    perl -MExtUtils::MakeMaker -le \
        'print MM->parse_version($ARGV[0])' filename
If you are author of a package and wonder if your $VERSION can be parsed, please try the above method.
In interactive mode you can try ``o debug'' which will list options for debugging the various parts of the package. The output may not be very useful for you as it's just a byproduct of my own testing, but if you have an idea which part of the package may have a bug, it's sometimes worth to give it a try and send me more specific output. You should know that ``o debug'' has built-in completion support.
use() or require() statements.
Currently the following keys in the hash reference $CPAN::Config are defined:
  build_cache        size of cache for directories to build modules
  build_dir          locally accessible directory to build modules
  index_expire       after how many days refetch index files
  cpan_home          local directory reserved for this package
  gzip               location of external program gzip
  inactivity_timeout breaks interactive Makefile.PLs after that
                     many seconds inactivity. Set to 0 to never break.
  inhibit_startup_message
                     if true, does not print the startup message
  keep_source        keep the source in a local directory?
  keep_source_where  where keep the source (if we do)
  make               location of external program make
  make_arg           arguments that should always be passed to 'make'
  make_install_arg   same as make_arg for 'make install'
  makepl_arg         arguments passed to 'perl Makefile.PL'
  pager              location of external program more (or any pager)
  tar                location of external program tar
  unzip              location of external program unzip
  urllist            arrayref to nearby CPAN sites (or equivalent locations)
You can set and query each of these options interactively in the cpan shell
with the command set defined within the o conf command:
Future development should be directed towards a better intergration of the other parts.
perl(1), CPAN::Nox(3)