Provided by: perl-doc_5.14.2-6ubuntu2_all bug


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


       Interactive mode:

         perl -MCPAN -e shell


       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

           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


       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 LWP,
       HTTP::Tiny, Net::FTP and certain external download clients to fetch distributions from the

       These are fetched from one or more mirrored CPAN (Comprehensive Perl Archive Network)
       sites and unpacked in a dedicated directory.

       The CPAN module also supports named and versioned bundles of modules. Bundles simplify
       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 using a simple FIFO mechanism.

       All methods provided are accessible in a programmer style and in an interactive shell

   CPAN::shell([$prompt, $command]) Starting Interactive Mode
       Enter interactive mode by running

           perl -MCPAN -e shell



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

       Once at the command line, type "h" for one-page help screen; the rest should be self-

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

       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 to these commands are either strings exactly matching the identification
         string of an object, or regular expressions matched case-insensitively against various
         attributes of the objects. The parser only recognizes a regular expression when you
         enclose it with slashes.

         The principle is that the number of objects found 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 more than one is found, each object is displayed with the terse
         method "as_glimpse".


           cpan> m Acme::MetaSyntactic
           Module id = Acme::MetaSyntactic
               CPAN_USERID  BOOK (Philippe Bruhat (BooK) <[...]>)
               CPAN_VERSION 0.99
               CPAN_FILE    B/BO/BOOK/Acme-MetaSyntactic-0.99.tar.gz
               UPLOAD_DATE  2006-11-06
               MANPAGE      Acme::MetaSyntactic - Themed metasyntactic variables names
               INST_FILE    /usr/local/lib/perl/5.10.0/Acme/
               INST_VERSION 0.99
           cpan> a BOOK
           Author id = BOOK
               EMAIL        [...]
               FULLNAME     Philippe Bruhat (BooK)
           cpan> d BOOK/Acme-MetaSyntactic-0.99.tar.gz
           Distribution id = B/BO/BOOK/Acme-MetaSyntactic-0.99.tar.gz
               CPAN_USERID  BOOK (Philippe Bruhat (BooK) <[...]>)
               CONTAINSMODS Acme::MetaSyntactic Acme::MetaSyntactic::Alias [...]
               UPLOAD_DATE  2006-11-06
           cpan> m /lorem/
           Module  = Acme::MetaSyntactic::loremipsum (BOOK/Acme-MetaSyntactic-0.99.tar.gz)
           Module    Text::Lorem            (ADEOLA/Text-Lorem-0.3.tar.gz)
           Module    Text::Lorem::More      (RKRIMEN/Text-Lorem-More-0.12.tar.gz)
           Module    Text::Lorem::More::Source (RKRIMEN/Text-Lorem-More-0.12.tar.gz)
           cpan> i /berlin/
           Distribution    BEATNIK/Filter-NumberLines-0.02.tar.gz
           Module  = DateTime::TimeZone::Europe::Berlin (DROLSKY/DateTime-TimeZone-0.7904.tar.gz)
           Module    Filter::NumberLines    (BEATNIK/Filter-NumberLines-0.02.tar.gz)
           Author          [...]

         The examples illustrate several aspects: the first three queries target modules,
         authors, or distros directly and yield exactly one result. The last two use regular
         expressions and yield several results. The last one targets all of bundles, modules,
         authors, and distros simultaneously. When more than one result is available, they are
         printed in one-line format.

       "get", "make", "test", "install", "clean" modules or distributions
         These commands take any number of arguments and investigate what is necessary to perform
         the action. Argument processing is as follows:

           known module name in format Foo/   module
           other embedded slash                     distribution
             - with trailing slash dot              directory
           enclosing slashes                        regexp
           known module name in format Foo::Bar     module

         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"). If an argument is enclosed in slashes it is treated as a
         regular expression: it is expanded and if the result is a single object (distribution,
         bundle or module), this object is processed.


             install Dummy::Perl                   # installs the module
             install AUXXX/Dummy-Perl-3.14.tar.gz  # installs that distribution
             install /Dummy-Perl-3.14/             # same if the regexp is unambiguous

         "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" is run unconditionally. An

           install <distribution_file>

         is also run unconditionally. But for

           install <module>

         CPAN checks whether an install is needed and prints module up to date if the
         distribution file containing the module doesn't need updating.

         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 of whether 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") to execute the command from scratch and attempt to continue past certain
         errors. See the section below on the "force" and the "fforce" pragma.

         The "notest" pragma skips the test part in the build process.


             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 module's pod
         documentation 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
         stored in the CHECKUMS files distributed on CPAN. The listing recurses into

         The second form limits or expands the output with shell globbing as in the following

               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 that may be
         changed in some future version.

         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
         reads the collected YAML files. If the stored signature matches the currently running
         perl, the stored state is loaded into memory such that persistence between sessions is
         effectively established.

       The "force" and the "fforce" pragma
         To speed things up in complex installation scenarios, 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 repeated only if the previous test was
         unsuccessful. The diagnostic message when 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 corresponding "test"
         was not successful.

         In all these cases, the user can override this stubborn 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 corresponding 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.

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

         The shell offers to run in downgraded 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

       Signals 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.
 ignores SIGPIPE. If the user sets "inactivity_timeout", a SIGALRM is used during
         the run of the "perl Makefile.PL" or "perl Build.PL" subprocess. A SIGALRM is also used
         during module version parsing, and is controlled by "version_timeout".

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

       "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

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

       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, no stats are provided.

       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.

       The "recent" command downloads a list of recent uploads to CPAN and displays them slowly.
       While the command is running, a $SIG{INT} exits the loop after displaying the current

       Note: This command requires XML::LibXML installed.

       Note: This whole command currently is just a hack and will probably change in future
       versions of, but the general approach will likely remain.

       Note: See also smoke

       recompile() is a special command that takes no argument and runs the make/test/install
       cycle with brute force over all installed dynamically loadable extensions (a.k.a. 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 reruns the tests and
       repeats every step that might have failed before.

       *** 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 just a hack and will probably change in future
       versions of, but the general approach will likely remain.

       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. deals with the four classes mentioned above, and those classes all
       share a set of methods. 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, 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

       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 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 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, takes care of 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.

       The usual shell redirection symbols " | " and ">" are recognized by the cpan shell only
       when surrounded by whitespace. So piping to pager or redirecting output into a file works
       somewhat as in a normal shell, with the stipulation that you must type extra spaces.


       When the CPAN module is used for the first time, a configuration dialogue 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/

       Default values defined in the CPAN/ file can be overridden in a user specific
       file: CPAN/ Such a file is best placed in "$HOME/.cpan/CPAN/",
       because "$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.


             o conf shell

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


             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 ""


             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 corresponding splice

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


             o conf urllist unshift
             o conf urllist splice 3 1
             o conf urllist http://cpan1.local http://cpan2.local

       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/ or
           CPAN/ 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
       The following keys in the hash reference $CPAN::Config are currently 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
                            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
         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
                            boolean if you want to see current command number
         commands_quote     preferred 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
                            whether to ask if opening a connection is ok before
                            urllist is specified
         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 environment variable FTP_PASSIVE is set
                            for downloads
         ftp_proxy          proxy host for ftp requests
         ftpstats_period    max number of days to keep download statistics
         ftpstats_size      max number of items to keep in the download statistics
         getcwd             see below
         gpg                path to external prg
         gzip               location of external program gzip
         halt_on_failure    stop processing after the first failure of queued
                            items or dependencies
         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
                            disable timeouts.
         index_expire       refetch index files after this many days
                            if true, suppress the startup message
         keep_source_where  directory in which to keep the source (if we do)
                            report loading of optional modules used by
         lynx               path to external prg
         make               location of external make program
         make_arg           arguments that should always be passed to 'make'
                            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'
                            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
         patches_dir        local directory containing patch files
         perl5lib_verbosity verbosity level for PERL5LIB additions
                            per default all untar operations are done with
                            Archive::Tar; by setting this variable to true
                            the external tar command is used if available
         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 no matter the setting
                            what to do if you are missing module prerequisites
                            ('follow' automatically, 'ask' me, or 'ignore')
                            For 'follow', also sets PERL_AUTOINSTALL and
                            PERL_EXTUTILS_AUTOINSTALL for "--defaultdeps" if
                            not already set
         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', 'atexit' or 'never')
         shell              your favorite shell
                            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)
                            skip testing when previously tested ok (according to
                            CPAN::Reporter history)
         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
         version_timeout    stops version parsing after this many seconds.
                            Default is 15 secs. Set to 0 to disable.
         wait_list          arrayref to a wait server to try (See CPAN::WAIT)
         wget               path to external prg
         yaml_load_code     enable YAML code deserialisation via CPAN::DeferredCode
         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.


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

       cwd Calls Cwd::cwd

           Calls Cwd::getcwd

           Calls Cwd::fastcwd

           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.




   The urllist parameter has CD-ROM support
       The "urllist" parameter of the configuration table contains a list of URLs used for
       downloading. If the list contains any "file" URLs, CPAN always tries 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 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 to see whether 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 (or some other YAML module configured in "yaml_module") installed, 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 that "randomize_urllist" be set;
       this introduces some amount of randomness into the URL selection.

   The "requires" and "build_requires" dependency declarations
       Since 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 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", asks the user and sets the default accordingly.

   Configuration for individual distributions (Distroprefs)
       (Note: This feature has been introduced in 1.8854 and is still considered beta

       Distributions on CPAN usually behave according to what we call the CPAN mantra. Or since
       the advent 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

       The distroprefs system of "" 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 "" configuration variables

       ·   specify dependencies the original maintainer forgot

       ·   disable the installation of an object altogether

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

       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 "" 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 document is treated as an entity that can specify the treatment of a single

       Filenames can be picked arbitrarily; "" 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

   Fallback Data::Dumper and Storable
       If neither your configured "yaml_module" nor is installed, 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 '
               nstore(\@y, shift)' somefile.yml

       In bootstrapping situations it is usually sufficient to translate only a few YAML files to
       Data::Dumper for crucial modules like "YAML::Syck", "" and "". 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.

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

         comment: "Demo"
           module: "Dancing::Queen"
           distribution: "^CHACHACHA/Dancing-"
           not_distribution: "\.zip$"
           perl: "/usr/local/cariba-perl/bin/perl"
             archname: "freebsd"
             not_cc: "gcc"
             DANCING_FLOOR: "Shubiduh"
         disabled: 1
           make: gmake
             - "--somearg=specialcase"

           env: {}

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

             - all
             - extra-all

           env: {}

           expect: []

           commandline: "echo SKIPPING make"

           args: []

           env: {}

           expect: []

           args: []

             WANT_TO_INSTALL: YES

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

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

             LWP: 5.8
             Test::Exception: 0.25
             Spiffy: 0.30

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

       comment [scalar]
           A comment

       cpanconfig [hash]
           Temporarily override assorted "" 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

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

       features [array] *** EXPERIMENTAL FEATURE ***
           Experimental implementation to deal with optional_features from META.yml. Still needs
           coordination with installer software and currently works only for META.yml declaring
           "dynamic_config=0". Use with caution.

       goto [string]
           The canonical name of a delegate distribution to install 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 Processing Instructions.

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

       match [hash]
           A hashref with one or more of the keys "distribution", "modules", "perl",
           "perlconfig", and "env" that specify whether a document is targeted at a specific CPAN
           distribution or installation.  Keys prefixed with "not_" negates the corresponding

           The corresponding values are interpreted as regular expressions. The "distribution"
           related one will be matched against the canonical distribution name, e.g.

           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 "" module.
           Keys prefixed with "not_" negates the corresponding match.

           The value associated with "env" is itself a hashref that is matched against
           corresponding values in the %ENV hash.  Keys prefixed with "not_" negates the
           corresponding match.

           If more than one restriction of "module", "distribution", etc. is specified, the
           results of the separately computed match values must all match. If so, 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 an
           external patch program. If the value for the "-p" parameter is 0 or 1 is determined by
           reading the patch beforehand. The path to each patch is either an absolute path on the
           local filesystem or relative to a patch directory specified in the "patches_dir"
           configuration variable or in the format of a canonical distro name. For examples
           please consult the distroprefs/ directory in the distribution (these examples
           are not installed by default).

           Note: if the "applypatch" program is installed and "CPAN::Config" knows about it and a
           patch is written by the "makepatch" program, then "" 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 Processing Instructions.

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

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

           A full commandline to run via "system()".  During execution, the environment variable
           PERL is set to $^X (but with an absolute path). If "commandline" is specified, "args"
           is not used.

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

           You must install the "Expect" module to use "eexpect". does not install it for

           "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. With
           "mode=deterministic", the timeout denotes the timeout per question; with
           "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
           watches the stream from the execution of the external program ("perl Makefile.PL",
           "perl Build.PL", "make", etc.).

           For "mode=deterministic", the injects the corresponding answer as soon as the
           stream matches the regular expression.

           For "mode=anyorder" answers 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 will happen with a question-answer pair after it has been used. In the
           default case (reuse=0) it is removed from the array, avoiding being used again
           accidentally. 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

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

       expect [array]
           You must install the "Expect" module to use "expect". does not install it for

           "expect: <array>" is a short notation for this "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 syntactic correctness.

   Example Distroprefs Files
       "" 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
       been warned:-)


       If you do not enter the shell, shell commands are available both 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.:


       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.

         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 returns only the first element of the list.

         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)) {

             # 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 schedule a cron job to watch 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 any output should all modules be up to date, 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.

         If you prefer to do it more in a programmerish style in one single process, something
         like this may better suit you:

           # 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 too much output every day, you may want to watch only 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

   Methods in the other Classes
           Returns a one-line description of the author

           Returns a multi-line description of the author

           Returns the author's email address

           Returns the author's name

           An alias for fullname

           Returns a one-line description of the bundle

           Returns a multi-line description of the bundle

           Recursively runs the "clean" method on all items contained in the bundle.

           Returns a list of objects' IDs contained in a bundle. The associated objects may be
           bundles, modules or distributions.

           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 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.

           Recursively runs the "get" method on all items contained in the bundle

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

           Like CPAN::Bundle::inst_file, but returns the $VERSION

           Returns 1 if the bundle itself and all its members are up-to-date.

           Recursively runs the "install" method on all items contained in the bundle

           Recursively runs the "make" method on all items contained in the bundle

           Recursively runs the "readme" method on all items contained in the bundle

           Recursively runs the "test" method on all items contained in the bundle

           Returns a one-line description of the distribution

           Returns a multi-line description of the distribution

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

           Returns a string of the form "AUTHORID/TARBALL", where AUTHORID is the author's PAUSE
           ID and TARBALL is the distribution filename.

           Returns the distribution filename without any archive suffix.  E.g "Foo-Bar-0.01"

           Changes to the directory where the distribution has been unpacked and runs "make
           clean" there.

           Returns a list of IDs of modules contained in a distribution file.  Works only for
           distributions listed in the 02packages.details.txt.gz file. This typically means that
           just most recent version of a distribution is covered.

           Changes to the directory where the distribution has been unpacked and runs something

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


           Returns the directory into which this distribution has been unpacked.

           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 does not refuse to take the action. See also the section above
           on the "force" and the "fforce" pragma.

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

           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" is issued in any case and if this fails, the install is
           cancelled. The cancellation can be avoided by letting "force" run the "install" for

           This install method only has the power to install the distribution if there are no
           dependencies in the way. To install an object along with all its dependencies, use

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

           Install all distributions that have tested successfully but not yet installed. See
           also "is_tested".

           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.

           Changes to the directory where the distribution has been unpacked and opens a subshell
           there. Exiting the subshell returns.

           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.

           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
           the external command html2text and runs it through the pager specified in

           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 distro name (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 against the regular expressions in the
           $root->{match}{module} attribute value. The two match values are ANDed together. Each
           of the two attributes are optional.

           Returns the hash reference that has been announced by a distribution as 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.

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

           Downloads report data for this distribution from and displays a
           subset of them.

           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.)

           Changes to the directory where the distribution has been unpacked and runs "make test"

           Returns 1 if all the modules contained in the distribution are up-to-date. Relies on

           Forces a reload of all indices.

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

           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.

           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 up-to-date, 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.

           Returns a multi-line description of the module

           Runs a clean on the distribution associated with this module.

           Returns the filename on CPAN that is associated with the module.

           Returns the latest version of this module available on CPAN.

           Runs a cvs_import on the distribution associated with this module.

           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)

           Returns the CPAN::Distribution object that contains the current version of this

           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 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

           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 maintenance

             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: approved by
               d   - allows distribution without restrictions
               r   - restricted distribution
               n   - no license at all

           Forces CPAN to perform a task it would normally refuse to do. Force takes as arguments
           a method name to be invoked and any number of additional arguments to pass that
           method.  The internals of the object get the needed changes so that does not
           refuse to take the action. See also the section above on the "force" and the "fforce"

           Runs a get on the distribution associated with this module.

           Returns the filename of the module found in @INC. The first file found is reported,
           just as perl itself stops searching @INC once it finds a module.

           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

           Returns the version number of the installed module in readable format.

           Returns the version number of the available module in readable format.

           Runs an "install" on the distribution associated with this module.

           Changes to the directory where the distribution associated with this module has been
           unpacked and opens a subshell there. Exiting the subshell returns.

           Runs a "make" on the distribution associated with this module.

           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 hasn't been installed yet.

           Runs a "perldoc" on this module.

           Runs a "readme" on the distribution associated with this module.

           Calls the reports() method on the associated distribution object.

           Runs a "test" on the distribution associated with this module.

           Returns 1 if the module is installed and up-to-date.

           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

       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, i.e. 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.


       The CPAN program is trying to depend on as little as possible so the user can use it in
       hostile environment. It works better the more goodies the environment provides. For
       example if you try in the CPAN shell

         install Bundle::CPAN


         install Bundle::CPANxxl

       you will find the shell more convenient than the bare shell before.

       If you have a local mirror of CPAN and can access all files with "file:" URLs, then you
       only need a perl later 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.


   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 with little enthusiasm).

       Debugging this module is more than a bit complex due to interference from the software
       producing the indices on CPAN, the mirroring process on CPAN, packaging, configuration,
       synchronicity, and even (gasp!) due to bugs within the module itself.

       For debugging the code of itself in interactive mode, some debugging aid can be
       turned on for most packages within 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 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

   Floppy, Zip, Offline Mode works nicely without network access, too. If you maintain machines that are not
       networked at all, you should consider working with "file:" URLs. You'll have to collect
       your modules somewhere first. So you might use 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. on the non-networked machines works nicely with this floppy. See also below the
       paragraph about CD-ROM support.

   Basic Utilities for Programmers
         Returns true if the module is installed. Used to load all modules into the running that are considered optional. The config variable "dontload_list" intercepts the
         "has_inst()" call such that an optional module is not loaded despite being available.
         For example, the following command will prevent "" from being loaded:

             cpan> o conf dontload_list push YAML

         See the source for details.

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

         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.


       There's no strong security layer in 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

   Cryptographically signed modules
       Since release 1.77, 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 key servers, like, and their port 11731 (the HKP protocol).

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


       Most functions in package CPAN are exported by default. The reason for this is that the
       primary use is intended for the cpan shell or for one-liners.


       When the CPAN shell enters a subshell via the look command, it sets the environment
       CPAN_SHELL_LEVEL to 1, or increments that variable 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.


       Populating a freshly installed perl with one's 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 installed for the current perl
       interpreter. It's recommended to run this command once only, and from then on maintain the
       file manually under a private name, say Bundle/ With a clever bundle file you
       can then simply say

           cpan> install Bundle::my_bundle

       then answer a few questions and go out for coffee (possibly even in a different city).

       Maintaining a bundle definition file means keeping track of two things: dependencies and
       interactivity. 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 annoying that so many
       distributions need some interactive configuring. So what you can try to accomplish in your
       private bundle file is to have the packages that need to be configured early in the file
       and the gentle ones later, so you can go out for coffee after a few minutes and leave to churn away untended.


       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 likely that you can
       configure ncftp so that it works through your firewall.

   Three basic types of firewalls
       Firewalls can be categorized into three basic types.

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

           To access servers outside these types of firewalls with perl (even for ftp), you need
           LWP or HTTP::Tiny.

       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 "".

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

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

           There are two that I can think off.

               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
               were not there.

           IP Masquerade
               This is when the firewall implemented in the kernel (via NAT, or networking
               address translation), 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

               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

   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 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...


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

           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 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/, install the new perl with the Configure option
           prefix, e.g.

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

           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?

           As of CPAN 1.9463, if you do not have permission to write the default perl library
           directories, CPAN's configuration process will ask you whether you want to bootstrap
           <local::lib>, which makes keeping a personal perl library directory easy.

           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, 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 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 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 bug report against at
  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
  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, 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

               % 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?


       15) I'm frequently irritated with the CPAN shell's inability to help me select a good

           CPAN can now help you select a "good" mirror, based on which ones have the lowest
           'ping' round-trip times.  From the shell, use the command 'o conf init urllist' and
           allow CPAN to automatically select mirrors for you.

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

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


           Also, feel free to play with experimental features. Run

             o conf init randomize_urllist ftpstats_period ftpstats_size

           and choose your favorite parameters. After a few downloads running the "hosts" command
           will probably assist you in choosing the best mirror sites.

       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.

       17) Older versions of had the original root directory of all tarballs in the build
           directory. Now there are always random characters appended to these directory names.
           Why was this done?

           The random characters are provided by File::Temp and ensure that each module's
           individual build directory is unique. This makes running in concurrent
           processes simultaneously safe.

       18) Speaking of the build directory. Do I have to clean it up myself?

           You have the choice to set the config variable "scan_cache" to "never". Then you must
           clean it up yourself. The other possible values, "atstart" and "atexit" clean up the
           build directory when you start or exit the CPAN shell, respectively. If you never
           start up the CPAN shell, you probably also have to clean up the build directory


   OLD PERL VERSIONS 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.

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

       In the year 2010 App::cpanminus was launched as a new approach to a cpan shell with a
       considerably smaller footprint. Very cool stuff.


       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


       Please report bugs via <>

       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.


       Andreas Koenig "<>"


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

       See <>


       Kawai,Takanori provides a Japanese translation of a very old version of this manpage at


       Many people enter the CPAN shell by running the cpan utility program which is installed in
       the same directory as perl itself. So if you have this directory in your PATH variable (or
       some equivalent in your operating system) then typing "cpan" in a console window will work
       for you as well. Above that the utility provides several commandline shortcuts.