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CPAN(3)								       CPAN(3)


NAME    [Toc]    [Back]

     CPAN - query, download and	build perl modules from	CPAN sites

SYNOPSIS    [Toc]    [Back]

     Interactive mode:

       perl -MCPAN -e shell;

     Batch mode:

       use CPAN;

       autobundle, clean, install, make, recompile, test

DESCRIPTION    [Toc]    [Back]

     The CPAN module is	designed to automate the make and install of perl
     modules and extensions. It	includes some searching	capabilities and knows
     how to use	Net::FTP or LWP	(or lynx or an external	ftp client) to fetch
     the raw data from the net.

     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.

     Interactive Mode    [Toc]    [Back]

     The interactive mode is entered by	running

	 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 selfexplanatory.







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CPAN(3)								       CPAN(3)



     The most common uses of the interactive modes are

     Searching for authors, bundles, distribution files	and modules
       There are corresponding one-letter commands a, b, d, and	m for each of
       the four	categories and another,	i for any of the mentioned four. Each
       of the four entities is implemented as a	class with slightly differing
       methods for displaying an object.

       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 Kvnig

	   cpan> a /andk/
	   Author id = ANDK
	       EMAIL	    a.koenig@franz.ww.TU-Berlin.DE
	       FULLNAME	    Andreas Kvnig

	   cpan> a /and.*rt/
	   Author	   ANDYD (Andy Dougherty)
	   Author	   MERLYN (Randal L. Schwartz)


     make, test, install, clean	 modules or distributions
       These commands do indeed	exist just as written above. Each of them
       takes any number	of arguments and investigates for each what it might
       be. Is it a distribution	file (recognized by embedded slashes), this
       file is being processed.	Is it a	module,	CPAN determines	the
       distribution file where this module is included and processes that.

       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't need to be updated.




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CPAN(3)								       CPAN(3)



       CPAN also keeps track of	what it	has done within	the current session
       and doesn'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
	   [...]


     readme, look module or distribution
       These two commands take only one	argument, be it	a module or a
       distribution file. readme displays the README of	the associated
       distribution file. 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::Shell

     The commands that are available in	the shell interface are	methods	in the
     package CPAN::Shell. If you enter the shell command, all your input is
     split by the Text::ParseWords::shellwords() routine which acts like most
     shells do.	The first word is being	interpreted as the method to be	called
     and the rest of the words are treated as arguments	to this	method.
     Continuation lines	are supported if a line	ends with a literal backslash.

     autobundle

     autobundle	writes a bundle	file into the $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

     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



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CPAN(3)								       CPAN(3)



     architecture and you'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.

     The four CPAN::* Classes: Author, Bundle, Module, Distribution

     Although it may be	considered internal, the class hierarchie does matter
     for both users and	programmer. CPAN.pm deals with above mentioned four
     classes, and all those classes share a set	of methods. It is a classical
     single polymorphism that is in effect.  A metaclass object	registers all
     objects of	all kinds and indexes them with	a string. The strings
     referencing objects have a	separated namespace (well, not completely
     separated):

	      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/Foo1.23.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 you 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 CPAN::Distribution.

     Programmer's interface

     If	you do not enter the shell, the	available shell	commands are both
     available as methods (CPAN::Shell->install(...)) and as functions in the
     calling package (install(...)).






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CPAN(3)								       CPAN(3)



     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.

     expand($type,@things)
       The IDs of all objects available	within a program are strings that can
       be expanded to the corresponding	real objects with the 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.

     Programming Examples
       This enables the	programmer to do operations that combine
       functionalities that are	available in the shell.

	   # 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;
	       # MakeMaker convention for undefined $VERSION:
	       next unless $mod->inst_version eq "undef";
	       print "No VERSION in ", $mod->id, "\n";
	   }


     Methods in	the four

     Cache Manager    [Toc]    [Back]

     Currently the cache manager only keeps track of the build directory
     ($CPAN::Config->{build_dir}). It is a simple FIFO mechanism that deletes
     complete directories below	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,



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CPAN(3)								       CPAN(3)



     then your sources will be deleted with the	same fifo mechanism.

     Bundles    [Toc]    [Back]

     A bundle is just a	perl module in the namespace Bundle:: that does	not
     define any	functions or methods. It usually only contains documentation.

     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.

     Prerequisites    [Toc]    [Back]

     If	you have a local mirror	of CPAN	and can	access all files with "file:"
     URLs, then	you only need a	perl better than perl5.003 to run this module.
     Otherwise Net::FTP	is strongly recommended. LWP may be required for nonUNIX
 systems or if	your nearest CPAN site is associated with an URL that
     is	not 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

     o declare their $VERSION variable in an easy to parse manner. This
       prerequisite can	hardly be relaxed because it consumes by far too much
       memory to load all packages into	the running program just to determine
       the $VERSION variable . Currently all programs that are dealing with
       version use something like this



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CPAN(3)								       CPAN(3)



	   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.

     o come as compressed or gzipped tarfiles or as zip	files and contain a
       Makefile.PL (well we try	to handle a bit	more, but without much
       enthusiasm).

     Debugging    [Toc]    [Back]

     The debugging of this module is pretty difficult, because we have
     interferences of the software producing the indices on CPAN, of the
     mirroring process on CPAN,	of packaging, of configuration,	of
     synchronicity, and	of bugs	within CPAN.pm.

     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.

     Floppy, Zip, and all that Jazz

     CPAN.pm works nicely without network too. If you maintain machines	that
     are not networked at all, you should consider working with	file:  URLs.
     Of	course,	you have to collect your modules somewhere first. So you might
     use CPAN.pm to put	together all you need on a networked machine. Then
     copy the $CPAN::Config->{keep_source_where} (but not
     $CPAN::Config->{build_dir}) directory on a	floppy.	This floppy is kind of
     a personal	CPAN. CPAN.pm on the non-networked machines works nicely with
     this floppy.

CONFIGURATION    [Toc]    [Back]

     When the CPAN module is installed a site wide configuration file is
     created as	CPAN/Config.pm.	The default values defined there can be
     overridden	in another configuration file: CPAN/MyConfig.pm. You can store
     this file in $HOME/.cpan/CPAN/MyConfig.pm if you want, because
     $HOME/.cpan is added to the search	path of	the CPAN module	before the
     use() or require()	statements.

     Currently the following keys in the hash reference	$CPAN::Config are
     defined:










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CPAN(3)								       CPAN(3)



       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:

     o conf <scalar option>
       prints the current value	of the scalar option

     o conf <scalar option> <value>
       Sets the	value of the scalar option to value

     o conf <list option>
       prints the current value	of the list option in MakeMaker's neatvalue
       format.

     o conf <list option> [shift|pop]
       shifts or pops the array	in the list option variable

     o conf <list option> [unshift|push|splice]	<list>
       works like the corresponding perl commands.

     CD-ROM support    [Toc]    [Back]

     The urllist parameter of the configuration	table contains a list of URLs
     that are to be used for downloading. If the list contains any file	URLs,
     CPAN always tries to get files from there first. This feature is disabled
     for index files. So the recommendation for	the owner of a CD-ROM with
     CPAN contents is: include your local, possibly outdated CD-ROM as a file
     URL at the	end of urllist,	e.g.

       o conf urllist push file://localhost/CDROM/CPAN

     CPAN.pm will then fetch the index files from one of the CPAN sites	that
     come at the beginning of urllist. It will later check for each module if



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CPAN(3)								       CPAN(3)



     there is a	local copy of the most recent version.

SECURITY    [Toc]    [Back]

     There's no	strong security	layer in CPAN.pm. CPAN.pm helps	you to install
     foreign, unmasked,	unsigned code on your machine. We compare to a
     checksum that comes from the net just as the distribution file itself. If
     somebody has managed to tamper with the distribution file,	they may have
     as	well tampered with the CHECKSUMS file. Future development will go
     towards strong authentification.

EXPORT    [Toc]    [Back]

     Most functions in package CPAN are	exported per default. The reason for
     this is that the primary use is intended for the cpan shell or for
     oneliners.

BUGS    [Toc]    [Back]

     we	should give coverage for _all_ of the CPAN and not just	the PAUSE
     part, right? In this discussion CPAN and PAUSE have become	equal -- but
     they are not. PAUSE is authors/ and modules/. CPAN	is PAUSE plus the
     clpa/, doc/, misc/, ports/, src/, scripts/.

     Future development	should be directed towards a better integration	of the
     other parts.

AUTHOR    [Toc]    [Back]

     Andreas Kvnig <a.koenig@mind.de>

SEE ALSO    [Toc]    [Back]

      
      
     perl(1), CPAN::Nox(3)


























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CPAN(3)								       CPAN(3)


								       PPPPaaaaggggeeee 11110000
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