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


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

SYNOPSIS
       Interactive mode:

         perl -MCPAN -e shell;

       Batch mode:

         use CPAN;

         autobundle, clean, install, make, recompile, test

STATUS
       This module will eventually be replaced by CPANPLUS. CPAN-
       PLUS is kind of a modern rewrite from ground up with
       greater extensibility and more features but no full com-
       patibility. If you're new to CPAN.pm, you probably should
       investigate 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.

DESCRIPTION
       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
       versioned bundles of modules. Bundles simplify the han-
       dling of sets of related modules. See Bundles below.

       The package contains a session manager and a cache man-
       ager. 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 man-
       ager 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
       "wq", "wr", "wd", "wl", and "wh" commands which send



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       queries to the WAIT server that has been configured for
       your installation.

       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::Read-
       Line 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 com-
       mand line (the latter only works if a real ReadLine inter-
       face 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-insen-
         sitively 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
         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 mod-
         ule is included and processes that, following any



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         dependencies named in the module's Makefile.PL (this
         behavior is controlled 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 distribu-
         tion 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.

         Example:

             cpan> install OpenGL
             OpenGL is up to date.
             cpan> force install OpenGL
             Running make
             OpenGL-0.4/
             OpenGL-0.4/COPYRIGHT
             [...]

         A "clean" command results in a

           make clean

         being executed within the distribution file's working
         directory.

       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 direc-
         tory.

       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, only the most recent one is listed.




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

         CPAN.pm ignores a SIGPIPE. If the user sets inactiv-
         ity_timeout, a SIGALRM is used during the run of the
         "perl Makefile.PL" subprocess.

       CPAN::Shell

       The commands that are available in the shell interface are
       methods in the package CPAN::Shell. If you enter the shell
       command, all your input is split by the Text::Parse-
       Words::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

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

       recompile

       recompile() is a very special command in that it takes no
       argument and runs the make/test/install cycle with brute
       force over all installed dynamically loadable extensions
       (aka XS modules) with 'force' in effect. The primary pur-
       pose 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.




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

       Although it may be considered internal, the class hierar-
       chy 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 poly-
       morphism 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. Develop-
       ers may mark their releases as unstable development ver-
       sions (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 mod-
       ule Foo circulates on CPAN in both version 1.23 and
       1.23_90, CPAN.pm offers a convenient way to install ver-
       sion 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::Dis-
       tribution.

       Programmer's interface

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

       There's currently only one class that has a stable inter-
       face - CPAN::Shell. All commands that are available in the
       CPAN shell are methods of the class CPAN::Shell. Each of



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       the commands that produce listings of modules ("r", "auto-
       bundle", "u") also return a list of the IDs of all modules
       within the list.

       expand($type,@things)
         The IDs of all objects available within a program are
         strings that can be expanded to the corresponding real
         objects with the "CPAN::Shell->expand("Module",@things)"
         method. Expand returns a list of CPAN::Module objects
         according to the @things arguments given. In scalar con-
         text it only returns the first element of the list.

       expandany(@things)
         Like expand, but returns objects of the appropriate
         type, i.e.  CPAN::Bundle objects for bundles, CPAN::Mod-
         ule objects for modules and CPAN::Distribution objects
         fro distributions.

       Programming Examples
         This enables the programmer to do operations that com-
         bine 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);
                 $obj->install;
             }

             # list all modules on my disk that have no VERSION number
             for $mod (CPAN::Shell->expand("Module","/./")){
                 next unless $mod->inst_file;
                 # MakeMaker convention for undefined $VERSION:
                 next unless $mod->inst_version eq "undef";
                 print "No VERSION in ", $mod->id, "\n";
             }

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

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

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

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




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

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

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

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

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

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

       Methods in the other Classes

       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 proven useful over a longer time and thus are
       unlikely to change.

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

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

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

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

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

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





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

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

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

       CPAN::Bundle::force($method,@args)
           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.

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

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

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

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

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

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

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

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





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

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

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

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

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

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

           there.

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

       CPAN::Distribution::force($method,@args)
           Forces CPAN to perform a task that 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.

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

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

       CPAN::Distribution::isa_perl()
           Returns 1 if this distribution file seems to be a perl
           distribution.  Normally this is derived from the file



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           name only, but the index from CPAN can contain a hint
           to achieve a return value of true for other filenames
           too.

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

       CPAN::Distribution::make()
           First runs the "get" method to make sure the 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"
           there.

       CPAN::Distribution::prereq_pm()
           Returns the hash reference that has been announced by
           a distribution as the PREREQ_PM hash in the Make-
           file.PL. Note: works only after an attempt has been
           made to "make" the distribution. Returns undef other-
           wise.

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

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

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

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

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

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

       CPAN::Module::as_glimpse()
           Returns a one-line description of the module





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

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

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

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

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

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

       CPAN::Module::force($method,@args)
           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.

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

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

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

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

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



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

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

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

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

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

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

       Cache Manager

       Currently the cache manager only keeps track of the build
       directory ($CPAN::Config->{build_dir}). It is a simple
       FIFO mechanism that deletes complete directories below
       "build_dir" as soon as the size of all directories there
       gets bigger than $CPAN::Config->{build_cache} (in MB). The
       contents of this cache may be used for later re-installa-
       tions 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::Con-
       fig->{keep_source_where}) where the original distribution
       files are kept. This directory is not covered by the cache
       manager and must be controlled by the user. If you choose
       to have the same directory as build_dir and as
       keep_source_where directory, then your sources will be
       deleted with the same fifo mechanism.

       Bundles

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

       It starts like a perl module with a package declaration
       and a $VERSION variable. After that the pod section looks



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       like any other pod with the only difference being that one
       special pod section exists starting with (verbatim):

               =head1 CONTENTS

       In this pod section each line obeys the format

               Module_Name [Version_String] [- optional text]

       The only required part is the first field, the name of a
       module (e.g. Foo::Bar, ie. not the name of the distribu-
       tion 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 con-
       vention 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 avail-
       able in the shell interface does that for you by including
       all currently installed modules in a snapshot bundle file.

       Prerequisites

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

       If you have neither Net::FTP nor LWP, there is a fallback
       mechanism implemented for an external ftp command or for
       an external lynx command.

       Finding packages and VERSION

       This module presumes that all packages on CPAN

       o declare their $VERSION variable in an easy to parse man-
         ner. 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 vari-
         able. Currently all programs that are dealing with ver-
         sion use something like this

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




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

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

       Debugging

       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 completion 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 con-
       sider working with file: URLs. Of course, you have to col-
       lect 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.

CONFIGURATION
       When the CPAN module is used for the first time, a config-
       uration dialog tries to determine a couple of site spe-
       cific 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/MyCon-
       fig.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



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       $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.
         inhibit_startup_message
                            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)
         prerequisites_policy
                            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.

       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 Make-
         Maker's neatvalue format.

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



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       "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 for-
       mat. Either:

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

       or

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

       urllist parameter has CD-ROM support

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

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

       CPAN.pm will then fetch the index files from one of the
       CPAN sites that come at the beginning of urllist. It will
       later check for each module if there is a local copy of
       the most recent version.

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

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

EXPORT
       Most functions in package CPAN are exported per default.



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       The reason for this is that the primary use is intended
       for the cpan shell or for one-liners.

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

           cpan> install Bundle::my_bundle

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

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

WORKING WITH CPAN.pm BEHIND FIREWALLS
       Thanks to Graham Barr for contributing the following para-
       graphs about the interaction between perl, and various
       firewall configurations. For further informations on fire-
       walls, 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.




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           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 "userAToutside.com"

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

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

           There are two that I can think off.

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

           IP Masquerade
               This is the firewall implemented in the Linux ker-
               nel, it allows you to hide a complete network
               behind one IP address. With this firewall no spe-
               cial compiling 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

               or

                   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, pre-
       sumably with a command such as



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           /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 config-
       ure something like

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

       Your mileage may vary...

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

           Most probably you do have the old version installed.
           This can happen if a module installs itself into a
           different directory in the @INC path than it was pre-
           viously installed. This is not really a CPAN.pm prob-
           lem, 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 expec-
           tations about who may install where in the @INC path
           and who uses which @INC array. In fine tuned environ-
           ments "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. Bun-
           dle/mybundle.pm), install the new perl with the Con-
           figure option prefix, e.g.

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

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

               cpan> install Bundle::mybundle

           and you're done.

       4)  When I install bundles or multiple modules with one



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           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 inspec-
           tion.

       5)  I am not root, how can I install a module in a per-
           sonal directory?

           You will most probably like something like this:

             o conf makepl_arg "LIB=~/myperl/lib \
                               INSTALLMAN1DIR=~/myperl/man/man1 \
                               INSTALLMAN3DIR=~/myperl/man/man3"
             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 envi-
           ronment 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.

           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 unde-
           tected 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



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           topologically correct order. It resolves perfectly
           well IFF all modules declare the prerequisites cor-
           rectly with the PREREQ_PM attribute to MakeMaker. For
           bundles which fail and you need to install often, it
           is recommended sort the Bundle definition file manu-
           ally. It is planned to improve the metadata 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 capitaliza-
           tion 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
           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> ! $CPAN::Config->{term_is_latin}=1

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

BUGS
       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.



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AUTHOR
       Andreas Koenig <andreas.koenigATanima.de>

TRANSLATIONS
       Kawai,Takanori provides a Japanese translation of this
       manpage at http://mem-
       ber.nifty.ne.jp/hippo2000/perltips/CPAN.htm

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















































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