MirBSD manpage: CPAN(3p)

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


     CPAN - query, download and build perl modules from CPAN


     Interactive mode:

       perl -MCPAN -e shell;

     Batch mode:

       use CPAN;

       autobundle, clean, install, make, recompile, test


     This module will eventually be replaced by CPANPLUS.
     CPANPLUS is kind of a modern rewrite from ground up with
     greater extensibility and more features but no full compati-
     bility. If you're new to CPAN.pm, you probably should inves-
     tigate if CPANPLUS is the better choice for you. If you're
     already used to CPAN.pm you're welcome to continue using it,
     if you accept that its development is mostly (though not
     completely) stalled.


     The CPAN module is designed to automate 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 lynx or an external ftp client) to fetch the raw data
     from the net.

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

     The CPAN module also supports the concept of named and ver-
     sioned bundles of modules. Bundles simplify the handling of
     sets of related modules. See Bundles below.

     The package contains a session manager and a cache manager.
     There is no status retained between sessions. The session
     manager keeps track of what has been fetched, built and
     installed in the current session. The cache manager keeps
     track of the disk space occupied by the make processes and
     deletes excess space according to a simple FIFO mechanism.

     For extended searching capabilities there's a plugin for
     CPAN available, "CPAN::WAIT". "CPAN::WAIT" is a full-text
     search engine that indexes all documents available in CPAN
     authors directories. If "CPAN::WAIT" is installed on your
     system, the interactive shell of CPAN.pm will enable the

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     "wq", "wr", "wd", "wl", and "wh" commands which send queries
     to the WAIT server that has been configured for your instal-

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

     Interactive Mode

     The interactive mode is entered by running

         perl -MCPAN -e shell

     which puts you into a readline interface. You will have the
     most fun if you install Term::ReadKey and Term::ReadLine to
     enjoy both history and command completion.

     Once you are on the command line, type 'h' 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 influ-
       ences 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>.

     make, test, install, clean  modules or distributions
       These commands take any number of arguments and investi-
       gate what is necessary to perform the action. If the argu-
       ment is a distribution file name (recognized by embedded
       slashes), it is processed. If it is a module, CPAN

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       determines the distribution file in which this module is
       included and processes that, following any dependencies
       named in the module's Makefile.PL (this behavior is con-
       trolled by prerequisites_policy.)

       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. The "force"
       command takes as a first argument the method to invoke
       (currently: "make", "test", or "install") and executes the
       command from scratch.


           cpan> install OpenGL
           OpenGL is up to date.
           cpan> force install OpenGL
           Running make

       A "clean" command results in a

         make clean

       being executed within the distribution file's working

     get, readme, look module or distribution
       "get" downloads a distribution file without further
       action. "readme" displays the README file of the associ-
       ated 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.

     ls author
       "ls" lists all distribution files in and below an author's
       CPAN directory. Only those files that contain modules are
       listed and if there is more than one for any given module,

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       only the most recent one is listed.

       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" subprocess.


     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 argu-
     ments to this method. Continuation lines are supported if a
     line ends with a literal backslash.


     "autobundle" writes a bundle file into the
     "$CPAN::Config->{cpan_home}/Bundle" directory. The file con-
     tains a list of all modules that are both available from
     CPAN and currently installed within @INC. The name of the
     bundle file is based on the current date and a counter.


     recompile() is a very special command in that it takes no
     argument and runs the make/test/install cycle with brute
     force over all installed dynamically loadable extensions
     (aka XS modules) with 'force' in effect. The primary purpose
     of this command is to finish a network installation. Ima-
     gine, you have a common source tree for two different archi-
     tectures. 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 Bun-
     dle 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

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     modules that CPAN uses is in turn depending on binary compa-
     tibility (so you cannot run CPAN commands), then you should
     try the CPAN::Nox module for recovery.

     The four "CPAN::*" Classes: Author, Bundle, Module, Distri-

     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 referenc-
     ing objects have a separated namespace (well, not completely

              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 con-
     venient 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

     Programmer's interface

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

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     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 com-
     mands that produce listings of modules ("r", "autobundle",
     "u") also return a list of the IDs of all modules within the

       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 con-
       text it only returns 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 fro

     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::MD5 Data::Dumper)){
               my $obj = CPAN::Shell->expand('Module',$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

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       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

         # 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

     Methods in the other Classes

     The programming interface for the classes CPAN::Module,
     CPAN::Distribution, CPAN::Bundle, and CPAN::Author is still
     considered beta and partially even alpha. In the following
     paragraphs only those methods are documented that have pro-
     ven useful over a longer time and thus are unlikely to

         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

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         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 con-
         tained in the bundle.

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

         Forces CPAN to perform a task that normally would have
         failed. 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.

         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 CPAN::Module::inst_file.

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

         Returns 1 if the bundle itself and all its members are

         Recursively runs the "install" method on all items con-
         tained in the bundle

         Recursively runs the "make" method on all items con-
         tained in the bundle


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         Recursively runs the "readme" method on all items con-
         tained in the bundle

         Recursively runs the "test" method on all items con-
         tained in the bundle

         Returns a one-line description of the distribution

         Returns a multi-line description of the distribution

         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 distri-
         bution 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

         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


         Returns the directory into which this distribution has
         been unpacked.

         Forces CPAN to perform a task that normally would have
         failed. 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.

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

         Changes to the directory where the distribution has been
         unpacked and runs the external command "make install"

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         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 cancella-
         tion can be avoided by letting "force" run the "install"
         for you.

         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 sub-
         shell returns.

         First runs the "get" method to make sure the distribu-
         tion is downloaded and unpacked. Changes to the direc-
         tory where the distribution has been unpacked and runs
         the external commands "perl Makefile.PL" and "make"

         Returns the hash reference that has been announced by a
         distribution as the PREREQ_PM hash in the Makefile.PL.
         Note: works only 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

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

         Returns 1 if all the modules contained in the distribu-
         tion are uptodate. Relies on containsmods.

         Forces a reload of all indices.

         Reloads all indices if they have been read more than
         "$CPAN::Config-"{index_expire}> days.

         CPAN::Author, CPAN::Bundle, CPAN::Module, and

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         CPAN::Distribution inherit this method. It prints the
         data structure associated with an object. Useful for
         debugging. Note: the data structure is considered inter-
         nal and thus subject to change without notice.

         Returns a one-line description of the module

         Returns a multi-line description of the module

         Runs a clean on the distribution associated with this

         Returns the filename on CPAN that is associated with the

         Returns the latest version of this module available on

         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

         Forces CPAN to perform a task that normally would have
         failed. 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.

         Runs a get on the distribution associated with this

         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.

         Returns the version number of the module in readable

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

         Changes to the directory where the distribution associ-
         ated with this module has been unpacked and opens a sub-
         shell there. Exiting the subshell returns.

         Runs a "make" on the distribution associated with this

         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

         Runs a "readme" on the distribution associated with this

         Runs a "test" on the distribution associated with this

         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 dis-
     tribution files are kept. This directory is not covered by

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     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.


     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 spe-
     cial 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 conven-
     tion 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 inter-
     face does that for you by including all currently installed
     modules in a snapshot bundle file.


     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

     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.

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     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 (well, we try to handle a bit more,
       but without much enthusiasm).


     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 code debugging in interactive mode you can try "o debug"
     which will list options for debugging the various parts of
     the code. You should know that "o debug" has built-in com-
     pletion support.

     For data debugging there is the "dump" command which takes
     the same arguments as make/test/install and outputs the
     object's Data::Dumper dump.

     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.


     When the CPAN module is used for the first time, a

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     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 configuration dialog can be started any time later again
     by issueing the command " o conf init " in the CPAN shell.

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

       build_cache        size of cache for directories to build modules
       build_dir          locally accessible directory to build modules
       index_expire       after this many days refetch index files
       cache_metadata     use serializer to cache metadata
       cpan_home          local directory reserved for this package
       dontload_hash      anonymous hash: modules in the keys will not be
                          loaded by the CPAN::has_inst() routine
       gzip               location of external program gzip
       histfile           file to maintain history between sessions
       histsize           maximum number of lines to keep in histfile
       inactivity_timeout breaks interactive Makefile.PLs after this
                          many seconds inactivity. Set to 0 to never break.
                          if true, does not print the startup message
       keep_source_where  directory in which to keep the source (if we do)
       make               location of external make program
       make_arg           arguments that should always be passed to 'make'
       make_install_arg   same as make_arg for 'make install'
       makepl_arg         arguments passed to 'perl Makefile.PL'
       pager              location of external program more (or any pager)
                          what to do if you are missing module prerequisites
                          ('follow' automatically, 'ask' me, or 'ignore')
       proxy_user         username for accessing an authenticating proxy
       proxy_pass         password for accessing an authenticating proxy
       scan_cache         controls scanning of cache ('atstart' or 'never')
       tar                location of external program tar
       term_is_latin      if true internal UTF-8 is translated to ISO-8859-1
                          (and nonsense for characters outside latin range)
       unzip              location of external program unzip
       urllist            arrayref to nearby CPAN sites (or equivalent locations)
       wait_list          arrayref to a wait server to try (See CPAN::WAIT)
       ftp_proxy,      }  the three usual variables for configuring
         http_proxy,   }  proxy requests. Both as CPAN::Config variables
         no_proxy      }  and as environment variables configurable.

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     You can set and query each of these options interactively in
     the cpan shell with the command set defined within the "o
     conf" command:

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

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

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

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

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

     Note on urllist parameter's format

     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.




     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

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     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


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


     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.


     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 some-
     times fails on calculating dependencies because not all
     modules define all MakeMaker attributes correctly, so a bun-
     dle 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.

     Thanks to Graham Barr for contributing the following para-
     graphs about the interaction between perl, and various

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     firewall configurations. For further informations 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

         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.

             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

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             This is the firewall implemented in the Linux ker-
             nel, it allows you to hide a complete network behind
             one IP address. With this firewall no special com-
             piling is needed as you can access hosts directly.

             For accessing ftp servers behind such firewalls you
             may need to set the environment variable
             "FTP_PASSIVE" to a true value, e.g.

                 env FTP_PASSIVE=1 perl -MCPAN -eshell


                 perl -MCPAN -e '$ENV{FTP_PASSIVE} = 1; shell'

     Configuring lynx or ncftp for going through a firewall

     If you can go through your firewall with e.g. lynx, presum-
     ably 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...


     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 dif-
         ferent 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 per-
         manently 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

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         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 option-
         ally rename the resulting bundle file (e.g.
         Bundle/mybundle.pm), install the new perl with the Con-
         figure 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 com-
         mand 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 inspec-

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

         You will most probably like something like this:

           o conf makepl_arg "LIB=~/myperl/lib \
                             INSTALLMAN1DIR=~/myperl/man/man1 \
           install Sybase::Sybperl

         You can make this setting permanent like all "o conf"
         settings with "o conf commit".

         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.

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         Another thing you should bear in mind is that the UNINST
         parameter should never be set if you are not root.

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

           look Sybase::Sybperl

     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 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 IFF all modules declare the
         prerequisites correctly with the PREREQ_PM attribute to
         MakeMaker. For bundles which fail and you need to
         install often, it is recommended sort the Bundle defini-
         tion file manually. It is planned to improve the meta-
         data situation for dependencies on CPAN in general, but
         this will still take some time.

     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 error msg about line 1 to
         4, setting meta input/output via the /etc/inputrc file.

         Some versions of readline are picky about capitalization
         in the /etc/inputrc file and specifically RedHat 6.2
         comes with a /etc/inputrc that contains the word "on" in
         lowercase. Change the occurrences of "on" to "On" and
         the bug should disappear.

     10) Some authors have strange characters in their names.

         Internally CPAN.pm uses the UTF-8 charset. If your ter-
         minal 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

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             cpan> ! $CPAN::Config->{term_is_latin}=1

         Extended support for converters will be made available
         as soon as perl becomes stable with regard to charset


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

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

     If a Makefile.PL requires special customization of
     libraries, prompts the user for special input, etc. then you
     may find CPAN is not able to build the distribution. In that
     case, you should attempt the traditional method of building
     a Perl module package from a shell.


     Andreas Koenig <andreas.koenig@anima.de>


     Kawai,Takanori provides a Japanese translation of this man-
     page at


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

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