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CPAN(3)		       Perl Programmers Reference Guide		       CPAN(3)

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

SYNOPSIS
       Interactive mode:

	 perl -MCPAN -e shell

       --or--

	 cpan

       Basic commands:

	 # Modules:

	 cpan> install Acme::Meta			# in the shell

	 CPAN::Shell->install("Acme::Meta");		# in perl

	 # Distributions:

	 cpan> install NWCLARK/Acme-Meta-0.02.tar.gz	# in the shell

	 CPAN::Shell->
	   install("NWCLARK/Acme-Meta-0.02.tar.gz");	# in perl

	 # module objects:

	 $mo = CPAN::Shell->expandany($mod);
	 $mo = CPAN::Shell->expand("Module",$mod);	# same thing

	 # distribution objects:

	 $do = CPAN::Shell->expand("Module",$mod)->distribution;
	 $do = CPAN::Shell->expandany($distro);		# same thing
	 $do = CPAN::Shell->expand("Distribution",
				   $distro);		# same thing

DESCRIPTION
       The CPAN module automates or at least simplifies the make and install
       of perl modules and extensions. It includes some primitive searching
       capabilities and knows how to use Net::FTP or LWP or some external
       download clients to fetch the distributions from the net.

       These 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. 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.

       CPAN::shell([$prompt, $command]) Starting Interactive Mode

       The interactive mode is entered by running

	   perl -MCPAN -e shell

       or

	   cpan

       which puts you into a readline interface. If "Term::ReadKey" and either
       "Term::ReadLine::Perl" or "Term::ReadLine::Gnu" are installed it
       supports both history and command completion.

       Once you are on the command line, type "h" to get a one page help
       screen and the rest should be self-explanatory.

       The function call "shell" takes two optional arguments, one is the
       prompt, the second is the default initial command line (the latter only
       works if a real ReadLine interface module is installed).

       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 exactly
	 matching 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 regular 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, the result is
	 displayed with the rather verbose method "as_string", but if we find
	 more than one, we display each object with the terse method
	 "as_glimpse".

       "get", "make", "test", "install", "clean" modules or distributions
	 These commands take any number of arguments and investigate what is
	 necessary to perform the action. If the argument is a distribution
	 file name (recognized by embedded slashes), it is processed. If it is
	 a module, CPAN determines the distribution file in which this module
	 is included and processes that, following any dependencies named in
	 the module's META.yml or Makefile.PL (this behavior is controlled by
	 the configuration parameter "prerequisites_policy".)

	 "get" downloads a distribution file and untars or unzips it, "make"
	 builds it, "test" runs the test suite, and "install" installs it.

	 Any "make" or "test" are run unconditionally. An

	   install <distribution_file>

	 also is run unconditionally. But for

	   install <module>

	 CPAN checks if an install is actually needed for it and prints module
	 up to date in the case that the distribution file containing the
	 module doesn't need to be updated.

	 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. It does not repeat a test run if the test has been
	 run successfully before. Same for install runs.

	 The "force" pragma may precede another command (currently: "get",
	 "make", "test", or "install") and executes the command from scratch
	 and tries to continue in case of some errors. See the section below
	 on the "force" and the "fforce" pragma.

	 The "notest" pragma may be used to skip the test part in the build
	 process.

	 Example:

	     cpan> notest install Tk

	 A "clean" command results in a

	   make clean

	 being executed within the distribution file's working directory.

       "readme", "perldoc", "look" module or distribution
	 "readme" displays the README file of the associated distribution.
	 "Look" gets and untars (if not yet done) the distribution file,
	 changes to the appropriate directory and opens a subshell process in
	 that directory. "perldoc" displays the pod documentation of the
	 module in html or plain text format.

       "ls" author
       "ls" globbing_expression
	 The first form lists all distribution files in and below an author's
	 CPAN directory as they are stored in the CHECKUMS files distributed
	 on CPAN. The listing goes recursive into all subdirectories.

	 The second form allows to limit or expand the output with shell
	 globbing as in the following examples:

	       ls JV/make*
	       ls GSAR/*make*
	       ls */*make*

	 The last example is very slow and outputs extra progress indicators
	 that break the alignment of the result.

	 Note that globbing only lists directories explicitly asked for, for
	 example FOO/* will not list FOO/bar/Acme-Sthg-n.nn.tar.gz. This may
	 be regarded as a bug and may be changed in future versions.

       "failed"
	 The "failed" command reports all distributions that failed on one of
	 "make", "test" or "install" for some reason in the currently running
	 shell session.

       Persistence between sessions
	 If the "YAML" or the "YAML::Syck" module is installed a record of the
	 internal state of all modules is written to disk after each step.
	 The files contain a signature of the currently running perl version
	 for later perusal.

	 If the configurations variable "build_dir_reuse" is set to a true
	 value, then CPAN.pm reads the collected YAML files. If the stored
	 signature matches the currently running perl the stored state is
	 loaded into memory such that effectively persistence between sessions
	 is established.

       The "force" and the "fforce" pragma
	 To speed things up in complex installation scenarios, CPAN.pm keeps
	 track of what it has already done and refuses to do some things a
	 second time. A "get", a "make", and an "install" are not repeated.  A
	 "test" is only repeated if the previous test was unsuccessful. The
	 diagnostic message when CPAN.pm refuses to do something a second time
	 is one of Has already been "unwrapped|made|tested successfully" or
	 something similar. Another situation where CPAN refuses to act is an
	 "install" if the according "test" was not successful.

	 In all these cases, the user can override the goatish behaviour by
	 prepending the command with the word force, for example:

	   cpan> force get Foo
	   cpan> force make AUTHOR/Bar-3.14.tar.gz
	   cpan> force test Baz
	   cpan> force install Acme::Meta

	 Each forced command is executed with the according part of its memory
	 erased.

	 The "fforce" pragma is a variant that emulates a "force get" which
	 erases the entire memory followed by the action specified,
	 effectively restarting the whole get/make/test/install procedure from
	 scratch.

       Lockfile
	 Interactive sessions maintain a lockfile, per default
	 "~/.cpan/.lock".  Batch jobs can run without a lockfile and do not
	 disturb each other.

	 The shell offers to run in degraded mode when another process is
	 holding the lockfile. This is an experimental feature that is not yet
	 tested very well. This second shell then does not write the history
	 file, does not use the metadata file and has a different prompt.

       Signals
	 CPAN.pm installs signal handlers for SIGINT and SIGTERM. While you
	 are in the cpan-shell it is intended that you can press "^C" anytime
	 and return to the cpan-shell prompt. A SIGTERM will cause the cpan-
	 shell to clean up and leave the shell loop. You can emulate the
	 effect of a SIGTERM by sending two consecutive SIGINTs, which usually
	 means by pressing "^C" twice.

	 CPAN.pm ignores a SIGPIPE. If the user sets "inactivity_timeout", a
	 SIGALRM is used during the run of the "perl Makefile.PL" or "perl
	 Build.PL" subprocess.

       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.

       hosts

       Note: this feature is still in alpha state and may change in future
       versions of CPAN.pm

       This commands provides a statistical overview over recent download
       activities. The data for this is collected in the YAML file
       "FTPstats.yml" in your "cpan_home" directory. If no YAML module is
       configured or YAML not installed, then no stats are provided.

       mkmyconfig

       mkmyconfig() writes your own CPAN::MyConfig file into your ~/.cpan/
       directory so that you can save your own preferences instead of the
       system wide ones.

       recent ***EXPERIMENTAL COMMAND***

       The "recent" command downloads a list of recent uploads to CPAN and
       displays them slowly. While the command is running $SIG{INT} is defined
       to mean that the loop shall be left after having displayed the current
       item.

       Note: This command requires XML::LibXML installed.

       Note: This whole command currently is a bit klunky and will probably
       change in future versions of CPAN.pm but the general approach will
       likely stay.

       Note: See also smoke

       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. The 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 invoke CPAN's
       recompile on the second 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.

       report Bundle|Distribution|Module

       The "report" command temporarily turns on the "test_report" config
       variable, then runs the "force test" command with the given arguments.
       The "force" pragma is used to re-run the tests and repeat every step
       that might have failed before.

       smoke ***EXPERIMENTAL COMMAND***

       *** WARNING: this command downloads and executes software from CPAN to
       your computer of completely unknown status. You should never do this
       with your normal account and better have a dedicated well separated and
       secured machine to do this. ***

       The "smoke" command takes the list of recent uploads to CPAN as
       provided by the "recent" command and tests them all. While the command
       is running $SIG{INT} is defined to mean that the current item shall be
       skipped.

       Note: This whole command currently is a bit klunky and will probably
       change in future versions of CPAN.pm but the general approach will
       likely stay.

       Note: See also recent

       upgrade [Module|/Regex/]...

       The "upgrade" command first runs an "r" command with the given
       arguments and then installs the newest versions of all modules that
       were listed by that.

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

       Although it may be considered internal, the class hierarchy does matter
       for both users and programmer. CPAN.pm deals with above mentioned four
       classes, and all those classes share a set of methods. A classical
       single polymorphism 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
       module version number which will also be reflected in the distribution
       name when you run 'make dist'), so the really hottest and newest
       distribution is not always the default.	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. 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.

       Integrating local directories

       Note: this feature is still in alpha state and may change in future
       versions of CPAN.pm

       Distribution objects are normally distributions from the CPAN, but
       there is a slightly degenerate case for Distribution objects, too, of
       projects held on the local disk. These distribution objects have the
       same name as the local directory and end with a dot. A dot by itself is
       also allowed for the current directory at the time CPAN.pm was used.
       All actions such as "make", "test", and "install" are applied directly
       to that directory. This gives the command "cpan ." an interesting
       touch: while the normal mantra of installing a CPAN module without
       CPAN.pm is one of

	   perl Makefile.PL		    perl Build.PL
		  ( go and get prerequisites )
	   make				    ./Build
	   make test			    ./Build test
	   make install			    ./Build install

       the command "cpan ." does all of this at once. It figures out which of
       the two mantras is appropriate, fetches and installs all prerequisites,
       cares for them recursively and finally finishes the installation of the
       module in the current directory, be it a CPAN module or not.

       The typical usage case is for private modules or working copies of
       projects from remote repositories on the local disk.

CONFIGURATION
       When the CPAN module is used for the first time, a configuration dialog
       tries to determine a couple of site specific options. The result of the
       dialog is stored in a hash reference  $CPAN::Config in a file
       CPAN/Config.pm.

       The default values defined in the CPAN/Config.pm file can be overridden
       in a user specific file: CPAN/MyConfig.pm. Such a file is best placed
       in $HOME/.cpan/CPAN/MyConfig.pm, because $HOME/.cpan is added to the
       search path of the CPAN module before the use() or require()
       statements. The mkmyconfig command writes this file for you.

       The "o conf" command has various bells and whistles:

       completion support
	   If you have a ReadLine module installed, you can hit TAB at any
	   point of the commandline and "o conf" will offer you completion for
	   the built-in subcommands and/or config variable names.

       displaying some help: o conf help
	   Displays a short help

       displaying current values: o conf [KEY]
	   Displays the current value(s) for this config variable. Without KEY
	   displays all subcommands and config variables.

	   Example:

	     o conf shell

	   If KEY starts and ends with a slash the string in between is
	   interpreted as a regular expression and only keys matching this
	   regex are displayed

	   Example:

	     o conf /color/

       changing of scalar values: o conf KEY VALUE
	   Sets the config variable KEY to VALUE. The empty string can be
	   specified as usual in shells, with '' or ""

	   Example:

	     o conf wget /usr/bin/wget

       changing of list values: o conf KEY SHIFT|UNSHIFT|PUSH|POP|SPLICE|LIST
	   If a config variable name ends with "list", it is a list. "o conf
	   KEY shift" removes the first element of the list, "o conf KEY pop"
	   removes the last element of the list. "o conf KEYS unshift LIST"
	   prepends a list of values to the list, "o conf KEYS push LIST"
	   appends a list of valued to the list.

	   Likewise, "o conf KEY splice LIST" passes the LIST to the according
	   splice command.

	   Finally, any other list of arguments is taken as a new list value
	   for the KEY variable discarding the previous value.

	   Examples:

	     o conf urllist unshift http://cpan.dev.local/CPAN
	     o conf urllist splice 3 1
	     o conf urllist http://cpan1.local http://cpan2.local ftp://ftp.perl.org

       reverting to saved: o conf defaults
	   Reverts all config variables to the state in the saved config file.

       saving the config: o conf commit
	   Saves all config variables to the current config file
	   (CPAN/Config.pm or CPAN/MyConfig.pm that was loaded at start).

       The configuration dialog can be started any time later again by issuing
       the command " o conf init " in the CPAN shell. A subset of the
       configuration dialog can be run by issuing "o conf init WORD" where
       WORD is any valid config variable or a regular expression.

       Config Variables

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

	 applypatch	    path to external prg
	 auto_commit	    commit all changes to config variables to disk
	 build_cache	    size of cache for directories to build modules
	 build_dir	    locally accessible directory to build modules
	 build_dir_reuse    boolean if distros in build_dir are persistent
	 build_requires_install_policy
			    to install or not to install when a module is
			    only needed for building. yes|no|ask/yes|ask/no
	 bzip2		    path to external prg
	 cache_metadata	    use serializer to cache metadata
	 commands_quote	    prefered character to use for quoting external
			    commands when running them. Defaults to double
			    quote on Windows, single tick everywhere else;
			    can be set to space to disable quoting
	 check_sigs	    if signatures should be verified
	 colorize_debug	    Term::ANSIColor attributes for debugging output
	 colorize_output    boolean if Term::ANSIColor should colorize output
	 colorize_print	    Term::ANSIColor attributes for normal output
	 colorize_warn	    Term::ANSIColor attributes for warnings
	 commandnumber_in_prompt
			    boolean if you want to see current command number
	 cpan_home	    local directory reserved for this package
	 curl		    path to external prg
	 dontload_hash	    DEPRECATED
	 dontload_list	    arrayref: modules in the list will not be
			    loaded by the CPAN::has_inst() routine
	 ftp		    path to external prg
	 ftp_passive	    if set, the envariable FTP_PASSIVE is set for downloads
	 ftp_proxy	    proxy host for ftp requests
	 getcwd		    see below
	 gpg		    path to external prg
	 gzip		    location of external program gzip
	 histfile	    file to maintain history between sessions
	 histsize	    maximum number of lines to keep in histfile
	 http_proxy	    proxy host for http requests
	 inactivity_timeout breaks interactive Makefile.PLs or Build.PLs
			    after this many seconds inactivity. Set to 0 to
			    never break.
	 index_expire	    after this many days refetch index files
	 inhibit_startup_message
			    if true, does not print the startup message
	 keep_source_where  directory in which to keep the source (if we do)
	 load_module_verbosity
			    report loading of optional modules used by CPAN.pm
	 lynx		    path to external prg
	 make		    location of external make program
	 make_arg	    arguments that should always be passed to 'make'
	 make_install_make_command
			    the make command for running 'make install', for
			    example 'sudo make'
	 make_install_arg   same as make_arg for 'make install'
	 makepl_arg	    arguments passed to 'perl Makefile.PL'
	 mbuild_arg	    arguments passed to './Build'
	 mbuild_install_arg arguments passed to './Build install'
	 mbuild_install_build_command
			    command to use instead of './Build' when we are
			    in the install stage, for example 'sudo ./Build'
	 mbuildpl_arg	    arguments passed to 'perl Build.PL'
	 ncftp		    path to external prg
	 ncftpget	    path to external prg
	 no_proxy	    don't proxy to these hosts/domains (comma separated list)
	 pager		    location of external program more (or any pager)
	 password	    your password if you CPAN server wants one
	 patch		    path to external prg
	 prefer_installer   legal values are MB and EUMM: if a module comes
			    with both a Makefile.PL and a Build.PL, use the
			    former (EUMM) or the latter (MB); if the module
			    comes with only one of the two, that one will be
			    used in any case
	 prerequisites_policy
			    what to do if you are missing module prerequisites
			    ('follow' automatically, 'ask' me, or 'ignore')
	 prefs_dir	    local directory to store per-distro build options
	 proxy_user	    username for accessing an authenticating proxy
	 proxy_pass	    password for accessing an authenticating proxy
	 randomize_urllist  add some randomness to the sequence of the urllist
	 scan_cache	    controls scanning of cache ('atstart' or 'never')
	 shell		    your favorite shell
	 show_unparsable_versions
			    boolean if r command tells which modules are versionless
	 show_upload_date   boolean if commands should try to determine upload date
	 show_zero_versions boolean if r command tells for which modules $version==0
	 tar		    location of external program tar
	 tar_verbosity	    verbosity level for the tar command
	 term_is_latin	    deprecated: if true Unicode is translated to ISO-8859-1
			    (and nonsense for characters outside latin range)
	 term_ornaments	    boolean to turn ReadLine ornamenting on/off
	 test_report	    email test reports (if CPAN::Reporter is installed)
	 unzip		    location of external program unzip
	 urllist	    arrayref to nearby CPAN sites (or equivalent locations)
	 use_sqlite	    use CPAN::SQLite for metadata storage (fast and lean)
	 username	    your username if you CPAN server wants one
	 wait_list	    arrayref to a wait server to try (See CPAN::WAIT)
	 wget		    path to external prg
	 yaml_load_code	    enable YAML code deserialisation
	 yaml_module	    which module to use to read/write YAML files

       You can set and query each of these options interactively in the cpan
       shell with the "o conf" or the "o conf init" command as specified
       below.

       "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.

       interactive editing: o conf init [MATCH|LIST]
	 Runs an interactive configuration dialog for matching variables.
	 Without argument runs the dialog over all supported config variables.
	 To specify a MATCH the argument must be enclosed by slashes.

	 Examples:

	   o conf init ftp_passive ftp_proxy
	   o conf init /color/

	 Note: this method of setting config variables often provides more
	 explanation about the functioning of a variable than the manpage.

       CPAN::anycwd($path): Note on config variable getcwd

       CPAN.pm changes the current working directory often and needs to
       determine its own current working directory. Per default it uses
       Cwd::cwd but if this doesn't work on your system for some reason,
       alternatives can be configured according to the following table:

       cwd Calls Cwd::cwd

       getcwd
	   Calls Cwd::getcwd

       fastcwd
	   Calls Cwd::fastcwd

       backtickcwd
	   Calls the external command cwd.

       Note on the format of the urllist parameter

       urllist parameters are URLs according to RFC 1738. We do a little
       guessing if your URL is not compliant, but if you have problems with
       "file" URLs, please try the correct format. Either:

	   file://localhost/whatever/ftp/pub/CPAN/

       or

	   file:///home/ftp/pub/CPAN/

       The urllist parameter has CD-ROM support

       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 there is a local copy of the most recent version.

       Another peculiarity of urllist is that the site that we could
       successfully fetch the last file from automatically gets a preference
       token and is tried as the first site for the next request. So if you
       add a new site at runtime it may happen that the previously preferred
       site will be tried another time. This means that if you want to
       disallow a site for the next transfer, it must be explicitly removed
       from urllist.

       Maintaining the urllist parameter

       If you have YAML.pm (or some other YAML module configured in
       "yaml_module") installed, CPAN.pm collects a few statistical data about
       recent downloads. You can view the statistics with the "hosts" command
       or inspect them directly by looking into the "FTPstats.yml" file in
       your "cpan_home" directory.

       To get some interesting statistics it is recommended to set the
       "randomize_urllist" parameter that introduces some amount of randomness
       into the URL selection.

       The "requires" and "build_requires" dependency declarations

       Since CPAN.pm version 1.88_51 modules declared as "build_requires" by a
       distribution are treated differently depending on the config variable
       "build_requires_install_policy". By setting
       "build_requires_install_policy" to "no" such a module is not being
       installed. It is only built and tested and then kept in the list of
       tested but uninstalled modules. As such it is available during the
       build of the dependent module by integrating the path to the
       "blib/arch" and "blib/lib" directories in the environment variable
       PERL5LIB. If "build_requires_install_policy" is set ti "yes", then both
       modules declared as "requires" and those declared as "build_requires"
       are treated alike. By setting to "ask/yes" or "ask/no", CPAN.pm asks
       the user and sets the default accordingly.

       Configuration for individual distributions (Distroprefs)

       (Note: This feature has been introduced in CPAN.pm 1.8854 and is still
       considered beta quality)

       Distributions on the CPAN usually behave according to what we call the
       CPAN mantra. Or since the event of Module::Build we should talk about
       two mantras:

	   perl Makefile.PL	perl Build.PL
	   make			./Build
	   make test		./Build test
	   make install		./Build install

       But some modules cannot be built with this mantra. They try to get some
       extra data from the user via the environment, extra arguments or
       interactively thus disturbing the installation of large bundles like
       Phalanx100 or modules with many dependencies like Plagger.

       The distroprefs system of "CPAN.pm" addresses this problem by allowing
       the user to specify extra informations and recipes in YAML files to
       either

       ·   pass additional arguments to one of the four commands,

       ·   set environment variables

       ·   instantiate an Expect object that reads from the console, waits for
	   some regular expressions and enters some answers

       ·   temporarily override assorted "CPAN.pm" configuration variables

       ·   specify dependencies that the original maintainer forgot to specify

       ·   disable the installation of an object altogether

       See the YAML and Data::Dumper files that come with the "CPAN.pm"
       distribution in the "distroprefs/" directory for examples.

       Filenames

       The YAML files themselves must have the ".yml" extension, all other
       files are ignored (for two exceptions see Fallback Data::Dumper and
       Storable below). The containing directory can be specified in "CPAN.pm"
       in the "prefs_dir" config variable. Try "o conf init prefs_dir" in the
       CPAN shell to set and activate the distroprefs system.

       Every YAML file may contain arbitrary documents according to the YAML
       specification and every single document is treated as an entity that
       can specify the treatment of a single distribution.

       The names of the files can be picked freely, "CPAN.pm" always reads all
       files (in alphabetical order) and takes the key "match" (see below in
       Language Specs) as a hashref containing match criteria that determine
       if the current distribution matches the YAML document or not.

       Fallback Data::Dumper and Storable

       If neither your configured "yaml_module" nor YAML.pm is installed
       CPAN.pm falls back to using Data::Dumper and Storable and looks for
       files with the extensions ".dd" or ".st" in the "prefs_dir" directory.
       These files are expected to contain one or more hashrefs.  For
       Data::Dumper generated files, this is expected to be done with by
       defining $VAR1, $VAR2, etc. The YAML shell would produce these with the
       command

	   ysh < somefile.yml > somefile.dd

       For Storable files the rule is that they must be constructed such that
       "Storable::retrieve(file)" returns an array reference and the array
       elements represent one distropref object each. The conversion from YAML
       would look like so:

	   perl -MYAML=LoadFile -MStorable=nstore -e '
	       @y=LoadFile(shift);
	       nstore(\@y, shift)' somefile.yml somefile.st

       In bootstrapping situations it is usually sufficient to translate only
       a few YAML files to Data::Dumper for the crucial modules like
       "YAML::Syck", "YAML.pm" and "Expect.pm". If you prefer Storable over
       Data::Dumper, remember to pull out a Storable version that writes an
       older format than all the other Storable versions that will need to
       read them.

       Blueprint

       The following example contains all supported keywords and structures
       with the exception of "eexpect" which can be used instead of "expect".

	 ---
	 comment: "Demo"
	 match:
	   module: "Dancing::Queen"
	   distribution: "^CHACHACHA/Dancing-"
	   perl: "/usr/local/cariba-perl/bin/perl"
	   perlconfig:
	     archname: "freebsd"
	 disabled: 1
	 cpanconfig:
	   make: gmake
	 pl:
	   args:
	     - "--somearg=specialcase"

	   env: {}

	   expect:
	     - "Which is your favorite fruit"
	     - "apple\n"

	 make:
	   args:
	     - all
	     - extra-all

	   env: {}

	   expect: []

	   commendline: "echo SKIPPING make"

	 test:
	   args: []

	   env: {}

	   expect: []

	 install:
	   args: []

	   env:
	     WANT_TO_INSTALL: YES

	   expect:
	     - "Do you really want to install"
	     - "y\n"

	 patches:
	   - "ABCDE/Fedcba-3.14-ABCDE-01.patch"

	 depends:
	   configure_requires:
	     LWP: 5.8
	   build_requires:
	     Test::Exception: 0.25
	   requires:
	     Spiffy: 0.30

       Language Specs

       Every YAML document represents a single hash reference. The valid keys
       in this hash are as follows:

       comment [scalar]
	   A comment

       cpanconfig [hash]
	   Temporarily override assorted "CPAN.pm" configuration variables.

	   Supported are: "build_requires_install_policy", "check_sigs",
	   "make", "make_install_make_command", "prefer_installer",
	   "test_report". Please report as a bug when you need another one
	   supported.

       depends [hash] *** EXPERIMENTAL FEATURE ***
	   All three types, namely "configure_requires", "build_requires", and
	   "requires" are supported in the way specified in the META.yml
	   specification. The current implementation merges the specified
	   dependencies with those declared by the package maintainer. In a
	   future implementation this may be changed to override the original
	   declaration.

       disabled [boolean]
	   Specifies that this distribution shall not be processed at all.

       goto [string]
	   The canonical name of a delegate distribution that shall be
	   installed instead. Useful when a new version, although it tests OK
	   itself, breaks something else or a developer release or a fork is
	   already uploaded that is better than the last released version.

       install [hash]
	   Processing instructions for the "make install" or "./Build install"
	   phase of the CPAN mantra. See below under Processiong Instructions.

       make [hash]
	   Processing instructions for the "make" or "./Build" phase of the
	   CPAN mantra. See below under Processiong Instructions.

       match [hash]
	   A hashref with one or more of the keys "distribution", "modules",
	   "perl", and "perlconfig" that specify if a document is targeted at
	   a specific CPAN distribution or installation.

	   The corresponding values are interpreted as regular expressions.
	   The "distribution" related one will be matched against the
	   canonical distribution name, e.g. "AUTHOR/Foo-Bar-3.14.tar.gz".

	   The "module" related one will be matched against all modules
	   contained in the distribution until one module matches.

	   The "perl" related one will be matched against $^X (but with the
	   absolute path).

	   The value associated with "perlconfig" is itself a hashref that is
	   matched against corresponding values in the %Config::Config hash
	   living in the " Config.pm " module.

	   If more than one restriction of "module", "distribution", and
	   "perl" is specified, the results of the separately computed match
	   values must all match. If this is the case then the hashref
	   represented by the YAML document is returned as the preference
	   structure for the current distribution.

       patches [array]
	   An array of patches on CPAN or on the local disk to be applied in
	   order via the external patch program. If the value for the "-p"
	   parameter is 0 or 1 is determined by reading the patch beforehand.

	   Note: if the "applypatch" program is installed and "CPAN::Config"
	   knows about it and a patch is written by the "makepatch" program,
	   then "CPAN.pm" lets "applypatch" apply the patch. Both "makepatch"
	   and "applypatch" are available from CPAN in the "JV/makepatch-*"
	   distribution.

       pl [hash]
	   Processing instructions for the "perl Makefile.PL" or "perl
	   Build.PL" phase of the CPAN mantra. See below under Processiong
	   Instructions.

       test [hash]
	   Processing instructions for the "make test" or "./Build test" phase
	   of the CPAN mantra. See below under Processiong Instructions.

       Processing Instructions

       args [array]
	   Arguments to be added to the command line

       commandline
	   A full commandline that will be executed as it stands by a system
	   call. During the execution the environment variable PERL will is
	   set to $^X (but with an absolute path). If "commandline" is
	   specified, the content of "args" is not used.

       eexpect [hash]
	   Extended "expect". This is a hash reference with four allowed keys,
	   "mode", "timeout", "reuse", and "talk".

	   "mode" may have the values "deterministic" for the case where all
	   questions come in the order written down and "anyorder" for the
	   case where the questions may come in any order. The default mode is
	   "deterministic".

	   "timeout" denotes a timeout in seconds. Floating point timeouts are
	   OK. In the case of a "mode=deterministic" the timeout denotes the
	   timeout per question, in the case of "mode=anyorder" it denotes the
	   timeout per byte received from the stream or questions.

	   "talk" is a reference to an array that contains alternating
	   questions and answers. Questions are regular expressions and
	   answers are literal strings. The Expect module will then watch the
	   stream coming from the execution of the external program ("perl
	   Makefile.PL", "perl Build.PL", "make", etc.).

	   In the case of "mode=deterministic" the CPAN.pm will inject the
	   according answer as soon as the stream matches the regular
	   expression.

	   In the case of "mode=anyorder" CPAN.pm will answer a question as
	   soon as the timeout is reached for the next byte in the input
	   stream. In this mode you can use the "reuse" parameter to decide
	   what shall happen with a question-answer pair after it has been
	   used. In the default case (reuse=0) it is removed from the array,
	   so it cannot be used again accidentally. In this case, if you want
	   to answer the question "Do you really want to do that" several
	   times, then it must be included in the array at least as often as
	   you want this answer to be given. Setting the parameter "reuse" to
	   1 makes this repetition unnecessary.

       env [hash]
	   Environment variables to be set during the command

       expect [array]
	   "expect: <array>" is a short notation for

	     eexpect:
	       mode: deterministic
	       timeout: 15
	       talk: <array>

       Schema verification with "Kwalify"

       If you have the "Kwalify" module installed (which is part of the
       Bundle::CPANxxl), then all your distroprefs files are checked for
       syntactical correctness.

       Example Distroprefs Files

       "CPAN.pm" comes with a collection of example YAML files. Note that
       these are really just examples and should not be used without care
       because they cannot fit everybody's purpose. After all the authors of
       the packages that ask questions had a need to ask, so you should watch
       their questions and adjust the examples to your environment and your
       needs. You have beend warned:-)

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(...)").  Before calling low-level
       commands it makes sense to initialize components of CPAN you need,
       e.g.:

	 CPAN::HandleConfig->load;
	 CPAN::Shell::setup_output;
	 CPAN::Index->reload;

       High-level commands do such initializations automatically.

       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") also return 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.

       expandany(@things)
	 Like expand, but returns objects of the appropriate type, i.e.
	 CPAN::Bundle objects for bundles, CPAN::Module objects for modules
	 and CPAN::Distribution objects for distributions. Note: it does not
	 expand to CPAN::Author objects.

       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 $mod (qw(Net::FTP Digest::SHA Data::Dumper)) {
		 CPAN::Shell->install($mod);
	     }

	     # 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";
	     }

	     # find out which distribution on CPAN contains a module:
	     print CPAN::Shell->expand("Module","Apache::Constants")->cpan_file

	 Or if you want to write a cronjob to watch The CPAN, you could list
	 all modules that need updating. First a quick and dirty way:

	     perl -e 'use CPAN; CPAN::Shell->r;'

	 If you don't want to get any output in the case that all modules are
	 up to date, you can parse the output of above command for the regular
	 expression //modules are up to date// and decide to mail the output
	 only if it doesn't match. Ick?

	 If you prefer to do it more in a programmer style in one single
	 process, maybe something like this suits you better:

	   # list all modules on my disk that have newer versions on CPAN
	   for $mod (CPAN::Shell->expand("Module","/./")) {
	     next unless $mod->inst_file;
	     next if $mod->uptodate;
	     printf "Module %s is installed as %s, could be updated to %s from CPAN\n",
		 $mod->id, $mod->inst_version, $mod->cpan_version;
	   }

	 If that gives you too much output every day, you maybe only want to
	 watch for three modules. You can write

	   for $mod (CPAN::Shell->expand("Module","/Apache|LWP|CGI/")) {

	 as the first line instead. Or you can combine some of the above
	 tricks:

	   # watch only for a new mod_perl module
	   $mod = CPAN::Shell->expand("Module","mod_perl");
	   exit if $mod->uptodate;
	   # new mod_perl arrived, let me know all update recommendations
	   CPAN::Shell->r;

       Methods in the other Classes

       CPAN::Author::as_glimpse()
	   Returns a one-line description of the author

       CPAN::Author::as_string()
	   Returns a multi-line description of the author

       CPAN::Author::email()
	   Returns the author's email address

       CPAN::Author::fullname()
	   Returns the author's name

       CPAN::Author::name()
	   An alias for fullname

       CPAN::Bundle::as_glimpse()
	   Returns a one-line description of the bundle

       CPAN::Bundle::as_string()
	   Returns a multi-line description of the bundle

       CPAN::Bundle::clean()
	   Recursively runs the "clean" method on all items contained in the
	   bundle.

       CPAN::Bundle::contains()
	   Returns a list of objects' IDs contained in a bundle. The
	   associated objects may be bundles, modules or distributions.

       CPAN::Bundle::force($method,@args)
	   Forces CPAN to perform a task that it normally would have refused
	   to do. Force takes as arguments a method name to be called and any
	   number of additional arguments that should be passed to the called
	   method.  The internals of the object get the needed changes so that
	   CPAN.pm does not refuse to take the action. The "force" is passed
	   recursively to all contained objects. See also the section above on
	   the "force" and the "fforce" pragma.

       CPAN::Bundle::get()
	   Recursively runs the "get" method on all items contained in the
	   bundle

       CPAN::Bundle::inst_file()
	   Returns the highest installed version of the bundle in either @INC
	   or "$CPAN::Config-"{cpan_home}>. Note that this is different from
	   CPAN::Module::inst_file.

       CPAN::Bundle::inst_version()
	   Like CPAN::Bundle::inst_file, but returns the $VERSION

       CPAN::Bundle::uptodate()
	   Returns 1 if the bundle itself and all its members are uptodate.

       CPAN::Bundle::install()
	   Recursively runs the "install" method on all items contained in the
	   bundle

       CPAN::Bundle::make()
	   Recursively runs the "make" method on all items contained in the
	   bundle

       CPAN::Bundle::readme()
	   Recursively runs the "readme" method on all items contained in the
	   bundle

       CPAN::Bundle::test()
	   Recursively runs the "test" method on all items contained in the
	   bundle

       CPAN::Distribution::as_glimpse()
	   Returns a one-line description of the distribution

       CPAN::Distribution::as_string()
	   Returns a multi-line description of the distribution

       CPAN::Distribution::author
	   Returns the CPAN::Author object of the maintainer who uploaded this
	   distribution

       CPAN::Distribution::pretty_id()
	   Returns a string of the form "AUTHORID/TARBALL", where AUTHORID is
	   the author's PAUSE ID and TARBALL is the distribution filename.

       CPAN::Distribution::base_id()
	   Returns the distribution filename without any archive suffix.  E.g
	   "Foo-Bar-0.01"

       CPAN::Distribution::clean()
	   Changes to the directory where the distribution has been unpacked
	   and runs "make clean" there.

       CPAN::Distribution::containsmods()
	   Returns a list of IDs of modules contained in a distribution file.
	   Only works for distributions listed in the
	   02packages.details.txt.gz file. This typically means that only the
	   most recent version of a distribution is covered.

       CPAN::Distribution::cvs_import()
	   Changes to the directory where the distribution has been unpacked
	   and runs something like

	       cvs -d $cvs_root import -m $cvs_log $cvs_dir $userid v$version

	   there.

       CPAN::Distribution::dir()
	   Returns the directory into which this distribution has been
	   unpacked.

       CPAN::Distribution::force($method,@args)
	   Forces CPAN to perform a task that it normally would have refused
	   to do. Force takes as arguments a method name to be called and any
	   number of additional arguments that should be passed to the called
	   method.  The internals of the object get the needed changes so that
	   CPAN.pm does not refuse to take the action. See also the section
	   above on the "force" and the "fforce" pragma.

       CPAN::Distribution::get()
	   Downloads the distribution from CPAN and unpacks it. Does nothing
	   if the distribution has already been downloaded and unpacked within
	   the current session.

       CPAN::Distribution::install()
	   Changes to the directory where the distribution has been unpacked
	   and runs the external command "make install" there. If "make" has
	   not yet been run, it will be run first. A "make test" will be
	   issued in any case and if this fails, the install will be canceled.
	   The cancellation can be avoided by letting "force" run the
	   "install" for you.

	   This install method has only the power to install the distribution
	   if there are no dependencies in the way. To install an object and
	   all of its dependencies, use CPAN::Shell->install.

	   Note that install() gives no meaningful return value. See
	   uptodate().

       CPAN::Distribution::install_tested()
	   Install all the distributions that have been tested sucessfully but
	   not yet installed. See also "is_tested".

       CPAN::Distribution::isa_perl()
	   Returns 1 if this distribution file seems to be a perl
	   distribution.  Normally this is derived from the file name only,
	   but the index from CPAN can contain a hint to achieve a return
	   value of true for other filenames too.

       CPAN::Distribution::is_tested()
	   List all the distributions that have been tested sucessfully but
	   not yet installed. See also "install_tested".

       CPAN::Distribution::look()
	   Changes to the directory where the distribution has been unpacked
	   and opens a subshell there. Exiting the subshell returns.

       CPAN::Distribution::make()
	   First runs the "get" method to make sure the distribution is
	   downloaded and unpacked. Changes to the directory where the
	   distribution has been unpacked and runs the external commands "perl
	   Makefile.PL" or "perl Build.PL" and "make" there.

       CPAN::Distribution::perldoc()
	   Downloads the pod documentation of the file associated with a
	   distribution (in html format) and runs it through the external
	   command lynx specified in "$CPAN::Config-"{lynx}>. If lynx isn't
	   available, it converts it to plain text with external command
	   html2text and runs it through the pager specified in
	   "$CPAN::Config-"{pager}>

       CPAN::Distribution::prefs()
	   Returns the hash reference from the first matching YAML file that
	   the user has deposited in the "prefs_dir/" directory. The first
	   succeeding match wins. The files in the "prefs_dir/" are processed
	   alphabetically and the canonical distroname (e.g.
	   AUTHOR/Foo-Bar-3.14.tar.gz) is matched against the regular
	   expressions stored in the $root->{match}{distribution} attribute
	   value.  Additionally all module names contained in a distribution
	   are matched agains the regular expressions in the
	   $root->{match}{module} attribute value. The two match values are
	   ANDed together. Each of the two attributes are optional.

       CPAN::Distribution::prereq_pm()
	   Returns the hash reference that has been announced by a
	   distribution as the the "requires" and "build_requires" elements.
	   These can be declared either by the "META.yml" (if authoritative)
	   or can be deposited after the run of "Build.PL" in the file
	   "./_build/prereqs" or after the run of "Makfile.PL" written as the
	   "PREREQ_PM" hash in a comment in the produced "Makefile". Note:
	   this method only works after an attempt has been made to "make" the
	   distribution. Returns undef otherwise.

       CPAN::Distribution::readme()
	   Downloads the README file associated with a distribution and runs
	   it through the pager specified in "$CPAN::Config-"{pager}>.

       CPAN::Distribution::reports()
	   Downloads report data for this distribution from
	   cpantesters.perl.org and displays a subset of them.

       CPAN::Distribution::read_yaml()
	   Returns the content of the META.yml of this distro as a hashref.
	   Note: works only after an attempt has been made to "make" the
	   distribution.  Returns undef otherwise. Also returns undef if the
	   content of META.yml is not authoritative. (The rules about what
	   exactly makes the content authoritative are still in flux.)

       CPAN::Distribution::test()
	   Changes to the directory where the distribution has been unpacked
	   and runs "make test" there.

       CPAN::Distribution::uptodate()
	   Returns 1 if all the modules contained in the distribution are
	   uptodate. Relies on containsmods.

       CPAN::Index::force_reload()
	   Forces a reload of all indices.

       CPAN::Index::reload()
	   Reloads all indices if they have not been read for more than
	   "$CPAN::Config-"{index_expire}> days.

       CPAN::InfoObj::dump()
	   CPAN::Author, CPAN::Bundle, CPAN::Module, and CPAN::Distribution
	   inherit this method. It prints the data structure associated with
	   an object. Useful for debugging. Note: the data structure is
	   considered internal and thus subject to change without notice.

       CPAN::Module::as_glimpse()
	   Returns a one-line description of the module in four columns: The
	   first column contains the word "Module", the second column consists
	   of one character: an equals sign if this module is already
	   installed and uptodate, a less-than sign if this module is
	   installed but can be upgraded, and a space if the module is not
	   installed. The third column is the name of the module and the
	   fourth column gives maintainer or distribution information.

       CPAN::Module::as_string()
	   Returns a multi-line description of the module

       CPAN::Module::clean()
	   Runs a clean on the distribution associated with this module.

       CPAN::Module::cpan_file()
	   Returns the filename on CPAN that is associated with the module.

       CPAN::Module::cpan_version()
	   Returns the latest version of this module available on CPAN.

       CPAN::Module::cvs_import()
	   Runs a cvs_import on the distribution associated with this module.

       CPAN::Module::description()
	   Returns a 44 character description of this module. Only available
	   for modules listed in The Module List
	   (CPAN/modules/00modlist.long.html or 00modlist.long.txt.gz)

       CPAN::Module::distribution()
	   Returns the CPAN::Distribution object that contains the current
	   version of this module.

       CPAN::Module::dslip_status()
	   Returns a hash reference. The keys of the hash are the letters "D",
	   "S", "L", "I", and <P>, for development status, support level,
	   language, interface and public licence respectively. The data for
	   the DSLIP status are collected by pause.perl.org when authors
	   register their namespaces. The values of the 5 hash elements are
	   one-character words whose meaning is described in the table below.
	   There are also 5 hash elements "DV", "SV", "LV", "IV", and <PV>
	   that carry a more verbose value of the 5 status variables.

	   Where the 'DSLIP' characters have the following meanings:

	     D - Development Stage  (Note: *NO IMPLIED TIMESCALES*):
	       i   - Idea, listed to gain consensus or as a placeholder
	       c   - under construction but pre-alpha (not yet released)
	       a/b - Alpha/Beta testing
	       R   - Released
	       M   - Mature (no rigorous definition)
	       S   - Standard, supplied with Perl 5

	     S - Support Level:
	       m   - Mailing-list
	       d   - Developer
	       u   - Usenet newsgroup comp.lang.perl.modules
	       n   - None known, try comp.lang.perl.modules
	       a   - abandoned; volunteers welcome to take over maintainance

	     L - Language Used:
	       p   - Perl-only, no compiler needed, should be platform independent
	       c   - C and perl, a C compiler will be needed
	       h   - Hybrid, written in perl with optional C code, no compiler needed
	       +   - C++ and perl, a C++ compiler will be needed
	       o   - perl and another language other than C or C++

	     I - Interface Style
	       f   - plain Functions, no references used
	       h   - hybrid, object and function interfaces available
	       n   - no interface at all (huh?)
	       r   - some use of unblessed References or ties
	       O   - Object oriented using blessed references and/or inheritance

	     P - Public License
	       p   - Standard-Perl: user may choose between GPL and Artistic
	       g   - GPL: GNU General Public License
	       l   - LGPL: "GNU Lesser General Public License" (previously known as
		     "GNU Library General Public License")
	       b   - BSD: The BSD License
	       a   - Artistic license alone
	       2   - Artistic license 2.0 or later
	       o   - open source: appoved by www.opensource.org
	       d   - allows distribution without restrictions
	       r   - restricted distribtion
	       n   - no license at all

       CPAN::Module::force($method,@args)
	   Forces CPAN to perform a task that it normally would have refused
	   to do. Force takes as arguments a method name to be called and any
	   number of additional arguments that should be passed to the called
	   method.  The internals of the object get the needed changes so that
	   CPAN.pm does not refuse to take the action. See also the section
	   above on the "force" and the "fforce" pragma.

       CPAN::Module::get()
	   Runs a get on the distribution associated with this module.

       CPAN::Module::inst_file()
	   Returns the filename of the module found in @INC. The first file
	   found is reported just like perl itself stops searching @INC when
	   it finds a module.

       CPAN::Module::available_file()
	   Returns the filename of the module found in PERL5LIB or @INC. The
	   first file found is reported. The advantage of this method over
	   "inst_file" is that modules that have been tested but not yet
	   installed are included because PERL5LIB keeps track of tested
	   modules.

       CPAN::Module::inst_version()
	   Returns the version number of the installed module in readable
	   format.

       CPAN::Module::available_version()
	   Returns the version number of the available module in readable
	   format.

       CPAN::Module::install()
	   Runs an "install" on the distribution associated with this module.

       CPAN::Module::look()
	   Changes to the directory where the distribution associated with
	   this module has been unpacked and opens a subshell there. Exiting
	   the subshell returns.

       CPAN::Module::make()
	   Runs a "make" on the distribution associated with this module.

       CPAN::Module::manpage_headline()
	   If module is installed, peeks into the module's manpage, reads the
	   headline and returns it. Moreover, if the module has been
	   downloaded within this session, does the equivalent on the
	   downloaded module even if it is not installed.

       CPAN::Module::perldoc()
	   Runs a "perldoc" on this module.

       CPAN::Module::readme()
	   Runs a "readme" on the distribution associated with this module.

       CPAN::Module::reports()
	   Calls the reports() method on the associated distribution object.

       CPAN::Module::test()
	   Runs a "test" on the distribution associated with this module.

       CPAN::Module::uptodate()
	   Returns 1 if the module is installed and up-to-date.

       CPAN::Module::userid()
	   Returns the author's ID of the module.

       Cache Manager

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

       Bundles

       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 being 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 (e.g.
       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
       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 non-UNIX systems or if your nearest CPAN site is
       associated with a 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.

UTILITIES
       Finding packages and VERSION

       This module presumes that all packages on CPAN

       · declare their $VERSION variable in an easy to parse manner. This
	 prerequisite can hardly be relaxed because it consumes 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

	     perl -MExtUtils::MakeMaker -le \
		 'print MM->parse_version(shift)' filename

	 If you are author of a package and wonder if your $VERSION can be
	 parsed, please try the above method.

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

       Debugging

       The debugging of this module is a bit complex, 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.

       For debugging the code of CPAN.pm itself in interactive mode some more
       or less useful debugging aid can be turned on for most packages within
       CPAN.pm with one of

       o debug package...
	 sets debug mode for packages.

       o debug -package...
	 unsets debug mode for packages.

       o debug all
	 turns debugging on for all packages.

       o debug number

       which sets the debugging packages directly. Note that "o debug 0" turns
       debugging off.

       What seems quite a successful strategy is the combination of "reload
       cpan" and the debugging switches. Add a new debug statement while
       running in the shell and then issue a "reload cpan" and see the new
       debugging messages immediately without losing the current context.

       "o debug" without an argument lists the valid package names and the
       current set of packages in debugging mode. "o debug" has built-in
       completion support.

       For debugging of CPAN data there is the "dump" command which takes the
       same arguments as make/test/install and outputs each object's
       Data::Dumper dump. If an argument looks like a perl variable and
       contains one of "$", "@" or "%", it is eval()ed and fed to Data::Dumper
       directly.

       Floppy, Zip, Offline Mode

       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. See also below the paragraph about CD-ROM support.

       Basic Utilities for Programmers

       has_inst($module)
	 Returns true if the module is installed. Used to load all modules
	 into the running CPAN.pm which are considered optional. The config
	 variable "dontload_list" can be used to intercept the "has_inst()"
	 call such that an optional module is not loaded despite being
	 available. For example the following command will prevent that
	 "YAML.pm" is being loaded:

	     cpan> o conf dontload_list push YAML

	 See the source for details.

       has_usable($module)
	 Returns true if the module is installed and is in a usable state.
	 Only useful for a handful of modules that are used internally. See
	 the source for details.

       instance($module)
	 The constructor for all the singletons used to represent modules,
	 distributions, authors and bundles. If the object already exists,
	 this method returns the object, otherwise it calls the constructor.

SECURITY
       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. But we try to make it easy to add security on demand:

       Cryptographically signed modules

       Since release 1.77 CPAN.pm has been able to verify cryptographically
       signed module distributions using Module::Signature.  The CPAN modules
       can be signed by their authors, thus giving more security.  The simple
       unsigned MD5 checksums that were used before by CPAN protect mainly
       against accidental file corruption.

       You will need to have Module::Signature installed, which in turn
       requires that you have at least one of Crypt::OpenPGP module or the
       command-line gpg tool installed.

       You will also need to be able to connect over the Internet to the
       public keyservers, like pgp.mit.edu, and their port 11731 (the HKP
       protocol).

       The configuration parameter check_sigs is there to turn signature
       checking on or off.

EXPORT
       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 one-
       liners.

ENVIRONMENT
       When the CPAN shell enters a subshell via the look command, it sets the
       environment CPAN_SHELL_LEVEL to 1 or increments it if it is already
       set.

       When CPAN runs, it sets the environment variable PERL5_CPAN_IS_RUNNING
       to the ID of the running process. It also sets
       PERL5_CPANPLUS_IS_RUNNING to prevent runaway processes which could
       happen with older versions of Module::Install.

       When running "perl Makefile.PL", the environment variable
       "PERL5_CPAN_IS_EXECUTING" is set to the full path of the "Makefile.PL"
       that is being executed. This prevents runaway processes with newer
       versions of Module::Install.

       When the config variable ftp_passive is set, all downloads will be run
       with the environment variable FTP_PASSIVE set to this value. This is in
       general a good idea as it influences both Net::FTP and LWP based
       connections. The same effect can be achieved by starting the cpan shell
       with this environment variable set. For Net::FTP alone, one can also
       always set passive mode by running libnetcfg.

POPULATE AN INSTALLATION WITH LOTS OF MODULES
       Populating a freshly installed perl with my favorite modules is pretty
       easy if you maintain a private bundle definition file. To get a useful
       blueprint of a bundle definition file, the command autobundle can be
       used on the CPAN shell command line. This command writes a bundle
       definition file for all modules that are installed for the currently
       running perl interpreter. It's recommended to run this command only
       once and from then on maintain the file manually under a private name,
       say Bundle/my_bundle.pm. With a clever bundle file you can then simply
       say

	   cpan> install Bundle::my_bundle

       then answer a few questions and then go out for a coffee.

       Maintaining a bundle definition file means keeping track of two things:
       dependencies and interactivity. CPAN.pm sometimes fails on calculating
       dependencies because not all modules define all MakeMaker attributes
       correctly, so a bundle definition file should specify prerequisites as
       early as possible. On the other hand, it's a bit annoying that many
       distributions need some interactive configuring. So what I try to
       accomplish in my private bundle file is to have the packages that need
       to be configured early in the file and the gentle ones later, so I can
       go out after a few minutes and leave CPAN.pm untended.

WORKING WITH CPAN.pm BEHIND FIREWALLS
       Thanks to Graham Barr for contributing the following paragraphs about
       the interaction between perl, and various firewall configurations. For
       further information on firewalls, it is recommended to consult the
       documentation that comes with the ncftp program. If you are unable to
       go through the firewall with a simple Perl setup, it is very likely
       that you can configure ncftp so that it works for your firewall.

       Three basic types of firewalls

       Firewalls can be categorized into three basic types.

       http firewall
	   This is where the firewall machine runs a web server and to access
	   the outside world you must do it via the web server. If you set
	   environment variables like http_proxy or ftp_proxy to a values
	   beginning with http:// or in your web browser you have to set proxy
	   information then you know you are running an http firewall.

	   To access servers outside these types of firewalls with perl (even
	   for ftp) you will need to use LWP.

       ftp firewall
	   This where the firewall machine runs an ftp server. This kind of
	   firewall will only let you access ftp servers outside the firewall.
	   This is usually done by connecting to the firewall with ftp, then
	   entering a username like "user@outside.host.com"

	   To access servers outside these type of firewalls with perl you
	   will need to use Net::FTP.

       One way visibility
	   I say one way visibility as these firewalls try to make themselves
	   look invisible to the users inside the firewall. An FTP data
	   connection is normally created by sending the remote server your IP
	   address and then listening for the connection. But the remote
	   server will not be able to connect to you because of the firewall.
	   So for these types of firewall FTP connections need to be done in a
	   passive mode.

	   There are two that I can think off.

	   SOCKS
	       If you are using a SOCKS firewall you will need to compile perl
	       and link it with the SOCKS library, this is what is normally
	       called a 'socksified' perl. With this executable you will be
	       able to connect to servers outside the firewall as if it is not
	       there.

	   IP Masquerade
	       This is the firewall implemented in the Linux kernel, it allows
	       you to hide a complete network behind one IP address. With this
	       firewall no special compiling is needed as you can access hosts
	       directly.

	       For accessing ftp servers behind such firewalls you usually
	       need to set the environment variable "FTP_PASSIVE" or the
	       config variable ftp_passive to a true value.

       Configuring lynx or ncftp for going through a firewall

       If you can go through your firewall with e.g. lynx, presumably with a
       command such as

	   /usr/local/bin/lynx -pscott:tiger

       then you would configure CPAN.pm with the command

	   o conf lynx "/usr/local/bin/lynx -pscott:tiger"

       That's all. Similarly for ncftp or ftp, you would configure something
       like

	   o conf ncftp "/usr/bin/ncftp -f /home/scott/ncftplogin.cfg"

       Your mileage may vary...

FAQ
       1)  I installed a new version of module X but CPAN keeps saying, I have
	   the old version installed

	   Most probably you do have the old version installed. This can
	   happen if a module installs itself into a different directory in
	   the @INC path than it was previously installed. This is not really
	   a CPAN.pm problem, you would have the same problem when installing
	   the module manually. The easiest way to prevent this behaviour is
	   to add the argument "UNINST=1" to the "make install" call, and that
	   is why many people add this argument permanently by configuring

	     o conf make_install_arg UNINST=1

       2)  So why is UNINST=1 not the default?

	   Because there are people who have their precise expectations about
	   who may install where in the @INC path and who uses which @INC
	   array. In fine tuned environments "UNINST=1" can cause damage.

       3)  I want to clean up my mess, and install a new perl along with all
	   modules I have. How do I go about it?

	   Run the autobundle command for your old perl and optionally rename
	   the resulting bundle file (e.g. Bundle/mybundle.pm), install the
	   new perl with the Configure option prefix, e.g.

	       ./Configure -Dprefix=/usr/local/perl-5.6.78.9

	   Install the bundle file you produced in the first step with
	   something like

	       cpan> install Bundle::mybundle

	   and you're done.

       4)  When I install bundles or multiple modules with one command there
	   is too much output to keep track of.

	   You may want to configure something like

	     o conf make_arg "| tee -ai /root/.cpan/logs/make.out"
	     o conf make_install_arg "| tee -ai /root/.cpan/logs/make_install.out"

	   so that STDOUT is captured in a file for later inspection.

       5)  I am not root, how can I install a module in a personal directory?

	   First of all, you will want to use your own configuration, not the
	   one that your root user installed. If you do not have permission to
	   write in the cpan directory that root has configured, you will be
	   asked if you want to create your own config. Answering "yes" will
	   bring you into CPAN's configuration stage, using the system config
	   for all defaults except things that have to do with CPAN's work
	   directory, saving your choices to your MyConfig.pm file.

	   You can also manually initiate this process with the following
	   command:

	       % perl -MCPAN -e 'mkmyconfig'

	   or by running

	       mkmyconfig

	   from the CPAN shell.

	   You will most probably also want to configure something like this:

	     o conf makepl_arg "LIB=~/myperl/lib \
			       INSTALLMAN1DIR=~/myperl/man/man1 \
			       INSTALLMAN3DIR=~/myperl/man/man3 \
			       INSTALLSCRIPT=~/myperl/bin \
			       INSTALLBIN=~/myperl/bin"

	   and then (oh joy) the equivalent command for Module::Build. That
	   would be

	     o conf mbuildpl_arg "--lib=~/myperl/lib \
			       --installman1dir=~/myperl/man/man1 \
			       --installman3dir=~/myperl/man/man3 \
			       --installscript=~/myperl/bin \
			       --installbin=~/myperl/bin"

	   You can make this setting permanent like all "o conf" settings with
	   "o conf commit" or by setting "auto_commit" beforehand.

	   You will have to add ~/myperl/man to the MANPATH environment
	   variable and also tell your perl programs to look into
	   ~/myperl/lib, e.g. by including

	     use lib "$ENV{HOME}/myperl/lib";

	   or setting the PERL5LIB environment variable.

	   While we're speaking about $ENV{HOME}, it might be worth
	   mentioning, that for Windows we use the File::HomeDir module that
	   provides an equivalent to the concept of the home directory on
	   Unix.

	   Another thing you should bear in mind is that the UNINST parameter
	   can be dangerous when you are installing into a private area
	   because you might accidentally remove modules that other people
	   depend on that are not using the private area.

       6)  How to get a package, unwrap it, and make a change before building
	   it?

	   Have a look at the "look" (!) command.

       7)  I installed a Bundle and had a couple of fails. When I retried,
	   everything resolved nicely. Can this be fixed to work on first try?

	   The reason for this is that CPAN does not know the dependencies of
	   all modules when it starts out. To decide about the additional
	   items to install, it just uses data found in the META.yml file or
	   the generated Makefile. An undetected missing piece breaks the
	   process. But it may well be that your Bundle installs some
	   prerequisite later than some depending item and thus your second
	   try is able to resolve everything.  Please note, CPAN.pm does not
	   know the dependency tree in advance and cannot sort the queue of
	   things to install in a topologically correct order. It resolves
	   perfectly well IF all modules declare the prerequisites correctly
	   with the PREREQ_PM attribute to MakeMaker or the "requires" stanza
	   of Module::Build. For bundles which fail and you need to install
	   often, it is recommended to sort the Bundle definition file
	   manually.

       8)  In our intranet we have many modules for internal use. How can I
	   integrate these modules with CPAN.pm but without uploading the
	   modules to CPAN?

	   Have a look at the CPAN::Site module.

       9)  When I run CPAN's shell, I get an error message about things in my
	   /etc/inputrc (or ~/.inputrc) file.

	   These are readline issues and can only be fixed by studying
	   readline configuration on your architecture and adjusting the
	   referenced file accordingly. Please make a backup of the
	   /etc/inputrc or ~/.inputrc and edit them. Quite often harmless
	   changes like uppercasing or lowercasing some arguments solves the
	   problem.

       10) Some authors have strange characters in their names.

	   Internally CPAN.pm uses the UTF-8 charset. If your terminal is
	   expecting ISO-8859-1 charset, a converter can be activated by
	   setting term_is_latin to a true value in your config file. One way
	   of doing so would be

	       cpan> o conf term_is_latin 1

	   If other charset support is needed, please file a bugreport against
	   CPAN.pm at rt.cpan.org and describe your needs. Maybe we can extend
	   the support or maybe UTF-8 terminals become widely available.

	   Note: this config variable is deprecated and will be removed in a
	   future version of CPAN.pm. It will be replaced with the conventions
	   around the family of $LANG and $LC_* environment variables.

       11) When an install fails for some reason and then I correct the error
	   condition and retry, CPAN.pm refuses to install the module, saying
	   "Already tried without success".

	   Use the force pragma like so

	     force install Foo::Bar

	   Or you can use

	     look Foo::Bar

	   and then 'make install' directly in the subshell.

       12) How do I install a "DEVELOPER RELEASE" of a module?

	   By default, CPAN will install the latest non-developer release of a
	   module. If you want to install a dev release, you have to specify
	   the partial path starting with the author id to the tarball you
	   wish to install, like so:

	       cpan> install KWILLIAMS/Module-Build-0.27_07.tar.gz

	   Note that you can use the "ls" command to get this path listed.

       13) How do I install a module and all its dependencies from the
	   commandline, without being prompted for anything, despite my CPAN
	   configuration (or lack thereof)?

	   CPAN uses ExtUtils::MakeMaker's prompt() function to ask its
	   questions, so if you set the PERL_MM_USE_DEFAULT environment
	   variable, you shouldn't be asked any questions at all (assuming the
	   modules you are installing are nice about obeying that variable as
	   well):

	       % PERL_MM_USE_DEFAULT=1 perl -MCPAN -e 'install My::Module'

       14) How do I create a Module::Build based Build.PL derived from an
	   ExtUtils::MakeMaker focused Makefile.PL?

	   http://search.cpan.org/search?query=Module::Build::Convert

	   http://www.refcnt.org/papers/module-build-convert

       15) What's the best CPAN site for me?

	   The urllist config parameter is yours. You can add and remove sites
	   at will. You should find out which sites have the best
	   uptodateness, bandwidth, reliability, etc. and are topologically
	   close to you. Some people prefer fast downloads, others
	   uptodateness, others reliability.  You decide which to try in which
	   order.

	   Henk P. Penning maintains a site that collects data about CPAN
	   sites:

	     http://www.cs.uu.nl/people/henkp/mirmon/cpan.html

       16) Why do I get asked the same questions every time I start the shell?

	   You can make your configuration changes permanent by calling the
	   command "o conf commit". Alternatively set the "auto_commit"
	   variable to true by running "o conf init auto_commit" and answering
	   the following question with yes.

COMPATIBILITY
       OLD PERL VERSIONS

       CPAN.pm is regularly tested to run under 5.004, 5.005, and assorted
       newer versions. It is getting more and more difficult to get the
       minimal prerequisites working on older perls. It is close to impossible
       to get the whole Bundle::CPAN working there. If you're in the position
       to have only these old versions, be advised that CPAN is designed to
       work fine without the Bundle::CPAN installed.

       To get things going, note that GBARR/Scalar-List-Utils-1.18.tar.gz is
       compatible with ancient perls and that File::Temp is listed as a
       prerequisite but CPAN has reasonable workarounds if it is missing.

       CPANPLUS

       This module and its competitor, the CPANPLUS module, are both much
       cooler than the other. CPAN.pm is older. CPANPLUS was designed to be
       more modular but it was never tried to make it compatible with CPAN.pm.

SECURITY ADVICE
       This software enables you to upgrade software on your computer and so
       is inherently dangerous because the newly installed software may
       contain bugs and may alter the way your computer works or even make it
       unusable. Please consider backing up your data before every upgrade.

BUGS
       Please report bugs via <http://rt.cpan.org/>

       Before submitting a bug, please make sure that the traditional method
       of building a Perl module package from a shell by following the
       installation instructions of that package still works in your
       environment.

AUTHOR
       Andreas Koenig "<andk@cpan.org>"

LICENSE
       This program is free software; you can redistribute it and/or modify it
       under the same terms as Perl itself.

       See <http://www.perl.com/perl/misc/Artistic.html>

TRANSLATIONS
       Kawai,Takanori provides a Japanese translation of this manpage at
       <http://homepage3.nifty.com/hippo2000/perltips/CPAN.htm>

SEE ALSO
       cpan, CPAN::Nox, CPAN::Version

perl v5.10.0			  2007-12-18			       CPAN(3)
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