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CPAN(3) - CPAN - query, download and build perl modules from CPAN sites - man 3 CPAN

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

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

       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 compatibility. If you're new to, you prob-
       ably should investigate if(3,n) CPANPLUS is the better choice for you.  If
       you're already used to you're welcome to continue using it, if(3,n)
       you accept(2,8) that its development is mostly (though not completely)

       The CPAN module is designed to automate the make and install of perl
       modules and extensions. It includes some primitive searching capabili-
       ties and knows how to use Net::FTP or LWP (or lynx or an external ftp
       client) to fetch the raw(3x,7,8,3x cbreak) data from the net.

       Modules are fetched from one or more of the mirrored CPAN (Comprehen-
       sive Perl Archive Network) sites and unpacked in(1,8) a dedicated directory.

       The CPAN module also supports the concept of named(5,8) and versioned bun-
       dles of modules. Bundles simplify the handling of sets of related mod-
       ules. 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(1,8) the current session. The
       cache manager keeps track of the disk space occupied by the make pro-
       cesses and deletes excess space according to a simple FIFO mechanism.

       For extended searching capabilities there's a plugin for CPAN avail-
       able, "CPAN::WAIT". "CPAN::WAIT" is a full-text search engine that
       indexes all documents available in(1,8) CPAN authors directories. If
       "CPAN::WAIT" is installed on your system, the interactive shell of will enable the "wq", "wr", "wd", "wl", and "wh" commands which
       send(2,n) queries to the WAIT server that has been configured for your

       All other methods provided are accessible in(1,8) a programmer style and in(1,8)
       an interactive shell style.

       Interactive Mode

       The interactive mode is entered by running

           perl -MCPAN -e shell

       which puts(3,n) you into a readline interface. You will have the most fun if(3,n)
       you install Term::ReadKey and Term::ReadLine to enjoy both history(1,3,n,1 builtins) and
       command completion.

       Once you are on the command line, type 'h' and the rest should be

       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(3,n) 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 men-
         tioned 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(3,n) of an object or regular expres-
         sions that are then matched case-insensitively against various
         attributes of the objects. The parser recognizes a regular expression
         only if(3,n) you enclose it between two slashes.

         The principle is that the number of found objects influences how an
         item is displayed. If the search finds one item, the result is dis-
         played with the rather verbose method "as_string", but if(3,n) we find
         more than one, we display each object with the terse method

       make, test, install, clean  modules or distributions
         These commands take any number of arguments and investigate what is
         necessary to perform the action. If the argument is a distribution
         file(1,n) name (recognized by embedded slashes), it is processed. If it is
         a module, CPAN determines the distribution file(1,n) in(1,8) which this module
         is included and processes that, following any dependencies named(5,8) in(1,8)
         the module's Makefile.PL (this behavior is controlled by prerequi-

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

           install <distribution_file>

         also is run unconditionally. But for

           install <module>

         CPAN checks if(3,n) an install is actually needed for it and prints module
         up to date in(1,8) the case that the distribution file(1,n) containing the mod-
         ule 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(1,2,n) regardless if(3,n) it
         succeeded or not. The "force" command takes as a first argument the
         method to invoke (currently: "make", "test", or "install") and exe-
         cutes the command from scratch.


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

         A "clean" command results in(1,8) a

           make clean

         being executed within the distribution file(1,n)'s working directory.

       get, .RE This package contains: .RS 4 .PD 0 .HP 4 advzip Recompression and test utility for zip files .HP 4 advpng Recompression utility for png files .HP 4 advmng Recompression utility for mng files .HP 4 advdef Recompression utility for deflate streams in .png, .mng and .gz files .PD .RE" href="/man.cgi/1/readme">readme, look(1,8,3 Search::Dict) module or distribution
         "get" downloads a distribution file(1,n) without further action. " .RE This package contains: .RS 4 .PD 0 .HP 4 advzip Recompression and test utility for zip files .HP 4 advpng Recompression utility for png files .HP 4 advmng Recompression utility for mng files .HP 4 advdef Recompression utility for deflate streams in .png, .mng and .gz files .PD .RE" href="/man.cgi/1/readme">readme"
         displays the README file(1,n) of the associated distribution. "Look" gets(3,n)
         and untars (if(3,n) not yet done) the distribution file(1,n), changes to the
         appropriate directory and opens a subshell process in(1,8) that directory.

       ls author
         "ls" lists all distribution files in(1,8) and below an author's CPAN
         directory. Only those files that contain modules are listed and if(3,n)
         there is more than one for any given module, only the most recent one
         is listed.

       Signals installs signal(2,7) handlers for SIGINT and SIGTERM. While you
         are in(1,8) the cpan-shell it is intended that you can press "^C" anytime
         and return to the cpan-shell prompt. A SIGTERM will cause the cpan-
         shell to clean up and leave the shell loop. You can emulate the
         effect of a SIGTERM by sending two consecutive SIGINTs, which usually
         means by pressing "^C" twice.
 ignores 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(1,8) the shell interface are methods in(1,8)
       the package CPAN::Shell. If you enter the shell command, all your input
       is split(1,n) by the Text::ParseWords::shellwords() routine which acts like
       most shells do. The first word is being interpreted as the method to be
       called and the rest of the words are treated as arguments to this
       method. Continuation lines are supported if(3,n) a line ends with a literal


       "autobundle" writes a bundle file(1,n) into the "$CPAN::Con-
       fig->{cpan_home}/Bundle" directory. The file(1,n) contains a list of all
       modules that are both available from CPAN and currently installed
       within @INC. The name of the bundle file(1,n) is based on the current date
       and a counter.


       recompile() is a very special command in(1,8) 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(1,8)
       effect. The primary purpose of this command is to finish a network
       installation. Imagine, you have a common source tree for two different
       architectures. You decide to do a completely independent fresh instal-
       lation. You start on one architecture with the help of a Bundle file(1,n)
       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 recom-
       pile on the second architecture and you're done.

       Another popular use for "recompile" is to act as a rescue in(1,8) case your
       perl breaks binary compatibility. If one of the modules that CPAN uses
       is in(1,8) turn depending on binary compatibility (so you cannot run CPAN
       commands), then you should try the CPAN::Nox module for recovery.

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

       Although it may be considered internal, the class hierarchy does matter
       for both users(1,5) and programmer. deals with above mentioned four
       classes, and all those classes share a set(7,n,1 builtins) of methods. A classical sin-
       gle polymorphism is in(1,8) effect. A metaclass object registers all objects
       of all kinds and indexes them with a string. The strings referencing
       objects have a separated namespace (well, not completely separated):

                Namespace                         Class

          words containing a "/" (slash)      Distribution
           words starting with Bundle::          Bundle
                 everything else            Module or Author

       Modules know their associated Distribution objects. They always refer
       to the most recent official release. Developers may mark their releases
       as unstable development versions (by inserting an underbar into the
       module version(1,3,5) number which will also be reflected in(1,8) the distribution
       name when you run 'make dist'), so the really hottest and newest dis-
       tribution is not always the default.  If a module Foo circulates on
       CPAN in(1,8) both version(1,3,5) 1.23 and 1.23_90, offers a convenient way
       to install version(1,3,5) 1.23 by saying

           install Foo

       This would install the complete distribution file(1,n) (say
       BAR/Foo-1.23.tar.gz) with all accompanying material. But if(3,n) you would
       like to install version(1,3,5) 1.23_90, you need to know where the distribu-
       tion file(1,n) 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::Mod-
       ule, the second by an object of class CPAN::Distribution.

       Programmer's interface

       If you do not enter the shell, the available shell commands are both
       available as methods ("CPAN::Shell->install(...)") and as functions in(1,8)
       the calling package ("install(...)").

       There's currently only one class that has a stable interface -
       CPAN::Shell. All commands that are available in(1,8) the CPAN shell are
       methods of the class CPAN::Shell. Each of the commands that produce
       listings of modules ("r", "autobundle", "u") also return a list of the
       IDs of all modules within the list.

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

       Programming Examples
         This enables the programmer to do operations that combine functional-
         ities that are available in(1,8) the shell.

             # install everything that is outdated on my disk:
             perl -MCPAN -e 'CPAN::Shell->install(CPAN::Shell->r)'

             # install my favorite programs if(3,n) 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(1,8) ", $mod->id, "\n";

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

         Or if(3,n) you want to write(1,2) 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(1,8) 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(1,8) the output
         only if(3,n) it doesn't match. Ick?

         If you prefer to do it more in(1,8) a programmer style in(1,8) one single
         process, maybe something like this suits you better:

           # list all modules on my disk that have newer versions on CPAN
           for $mod (CPAN::Shell->expand("Module","/./")){
             next unless $mod->inst_file;
             next if(3,n) $mod->uptodate;
             printf(1,3,1 builtins) "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(1,2)

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

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

           # watch only for a new mod_perl module
           $mod = CPAN::Shell->expand("Module","mod_perl");
           exit(3,n,1 builtins) if(3,n) $mod->uptodate;
           # new mod_perl arrived, let me know all update(7,n) recommendations

       Methods in(1,8) the other Classes

       The programming interface for the classes CPAN::Module, CPAN::Distribu-
       tion, CPAN::Bundle, and CPAN::Author is still considered beta and par-
       tially even alpha. In the following paragraphs only those methods are
       documented that have proven useful over a longer time(1,2,n) and thus are
       unlikely to change.

           Returns a one-line description of the author

           Returns a multi-line description of the author

           Returns the author's email address

           Returns the author's name

           An alias for fullname

           Returns a one-line description of the bundle

           Returns a multi-line description of the bundle

           Recursively runs the "clean" method on all items contained in(1,8) the

           Returns a list of objects' IDs contained in(1,8) a bundle. The associ-
           ated objects may be bundles, modules or distributions.

           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
           does not refuse to take the action. The "force" is passed recur-
           sively to all contained objects.

           Recursively runs the "get" method on all items contained in(1,8) the

           Returns the highest installed version(1,3,5) of the bundle in(1,8) either @INC
           or "$CPAN::Config-"{cpan_home}>. Note that this is different from

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

           Returns 1 if(3,n) the bundle itself and all its members are uptodate.

           Recursively runs the "install" method on all items contained in(1,8) the

           Recursively runs the "make" method on all items contained in(1,8) the

           Recursively runs the " .RE This package contains: .RS 4 .PD 0 .HP 4 advzip Recompression and test utility for zip files .HP 4 advpng Recompression utility for png files .HP 4 advmng Recompression utility for mng files .HP 4 advdef Recompression utility for deflate streams in .png, .mng and .gz files .PD .RE" href="/man.cgi/1/readme">readme" method on all items contained in(1,8) the

           Recursively runs the "test" method on all items contained in(1,8) the

           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(1,8) a distribution file.
           Only works for distributions listed in(1,8) the 02pack-
           ages.details.txt.gz file. This typically means that only the most
           recent version(1,3,5) of a distribution is covered.

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

               cvs(1,5) -d $cvs_root import -m $cvs_log $cvs_dir $userid v$version(1,3,5)


           Returns the directory into which this distribution has been

           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
           does not refuse to take the action.

           Downloads the distribution from CPAN and unpacks it. Does nothing
           if(3,n) the distribution has already been downloaded and unpacked within
           the current session.

           Changes to the directory where the distribution has been unpacked
           and runs the external command "make install" there. If "make" has
           not yet been run, it will be run first. A "make test" will be
           issued in(1,8) any case and if(3,n) this fails, the install will be canceled.
           The cancellation can be avoided by letting "force" run the
           "install" for you.

           Returns 1 if(3,n) this distribution file(1,n) seems to be a perl distribu-
           tion.  Normally this is derived from the file(1,n) name only, but the
           index from CPAN can contain a hint to achieve a return value of
           true for other filenames too.

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

           First runs the "get" method to make sure the distribution is down-
           loaded and unpacked. Changes to the directory where the distribu-
           tion has been unpacked and runs the external commands "perl Make-
           file.PL" and "make" there.

           Returns the hash reference that has been announced by a distribu-
           tion as the PREREQ_PM hash in(1,8) the Makefile.PL. Note: works only
           after an attempt has been made to "make" the distribution. Returns
           undef otherwise.

           Downloads the README file(1,n) associated with a distribution and runs
           it through the pager specified in(1,8) "$CPAN::Config-"{pager}>.

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

           Returns 1 if(3,n) all the modules contained in(1,8) the distribution are
           uptodate. Relies on containsmods.

           Forces a reload of all indices.

           Reloads all indices if(3,n) they have been read(2,n,1 builtins) more than "$CPAN::Con-
           fig-"{index_expire}> days.

           CPAN::Author, CPAN::Bundle, CPAN::Module, and CPAN::Distribution
           inherit this method. It prints the data structure associated with
           an object. Useful for debugging. Note: the data structure is con-
           sidered internal 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 module.

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

           Returns the latest version(1,3,5) of this module available on CPAN.

           Runs a cvs_import on the distribution associated with this module.

           Returns a 44 character description of this module. Only available
           for modules listed in(1,8) The Module List (CPAN/modules/00mod-
           list.long.html or 00modlist.long.txt.gz)

           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
           does not refuse to take the action.

           Runs a get on the distribution associated with this module.

           Returns the filename of the module found in(1,8) @INC. The first file(1,n)
           found is reported just like perl itself stops searching @INC when
           it finds a module.

           Returns the version(1,3,5) number of the module in(1,8) readable format.

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

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

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

           If module is installed, peeks into the module's manpage, reads the
           headline and returns it. Moreover, if(3,n) the module has been down-
           loaded within this session, does the equivalent on the downloaded
           module even if(3,n) it is not installed.

           Runs a " .RE This package contains: .RS 4 .PD 0 .HP 4 advzip Recompression and test utility for zip files .HP 4 advpng Recompression utility for png files .HP 4 advmng Recompression utility for mng files .HP 4 advdef Recompression utility for deflate streams in .png, .mng and .gz files .PD .RE" href="/man.cgi/1/readme">readme" on the distribution associated with this module.

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

           Returns 1 if(3,n) 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(3,n) bigger than $CPAN::Config->{build_cache} (in(1,8)
       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 directo-
       ries for building modules on different architectures.

       There is another directory ($CPAN::Config->{keep_source_where}) where
       the original distribution files are kept. This directory is not covered
       by the cache manager and must be controlled by the user. If you choose
       to have the same directory as build_dir and as keep_source_where direc-
       tory, then your sources will be deleted with the same fifo mechanism.


       A bundle is just a perl module in(1,8) the namespace Bundle:: that does not
       define any functions or methods. It usually only contains documenta-

       It starts like a perl module with a package declaration and a $VERSION
       variable. After that the pod section looks like any other pod with the
       only difference being that one special pod section exists starting with

               =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(1,n)). The rest of the
       line is optional. The comment part is delimited by a dash just as in(1,8)
       the man(1,5,7) page header.

       The distribution of a bundle should follow the same convention as other

       Bundles are treated specially in(1,8) the CPAN package. If you say 'install
       Bundle::Tkkit' (assuming such a bundle exists), CPAN will install all
       the modules in(1,8) the CONTENTS section of the pod. You can install your
       own Bundles locally by placing a conformant Bundle file(1,n) somewhere into
       your @INC path. The autobundle() command which is available in(1,8) the
       shell interface does that for you by including all currently installed
       modules in(1,8) a snapshot bundle file.


       If you have a local mirror of CPAN and can access(2,5) 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(3,n) your nearest CPAN site is associ-
       ated 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 com-

       Finding packages and VERSION

       This module presumes that all packages on CPAN

        declare their $VERSION variable in(1,8) an easy to parse manner. This pre-
         requisite can hardly be relaxed because it consumes far too much mem-
         ory to load(7,n) all packages into the running program just to determine
         the $VERSION variable. Currently all programs that are dealing with
         version(1,3,5) use something like this

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

         If you are author of a package and wonder if(3,n) 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


       The debugging of this module is a bit complex, because we have inter-
       ferences of the software producing the indices on CPAN, of the mirror-
       ing process on CPAN, of packaging, of configuration, of synchronicity,
       and of bugs within

       For code debugging in(1,8) 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

       Floppy, Zip, Offline Mode 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 to put together all you need on a networked machine.
       Then copy the $CPAN::Config->{keep_source_where} (but not $CPAN::Con-
       fig->{build_dir}) directory on a floppy. This floppy is kind of a per-
       sonal CPAN. 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(1,2,n), a configuration dialog(1,3,n)
       tries to determine a couple of site specific options. The result of the
       dialog(1,3,n) is stored in(1,8) a hash reference  $CPAN::Config in(1,8) a file(1,n) CPAN/Con-

       The default values defined in(1,8) the CPAN/ file(1,n) can be overridden
       in(1,8) a user specific file: CPAN/ Such a file(1,n) is best placed
       in(1,8) $HOME/.cpan/CPAN/, because $HOME/.cpan is added to the
       search path of the CPAN module before the use() or require() state-

       The configuration dialog(1,3,n) can be started any time(1,2,n) later again by issue-
       ing the command " o conf(3,5) init " in(1,8) the CPAN shell.

       Currently the following keys in(1,8) the hash reference $CPAN::Config are

         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(1,8) the keys will not be
                            loaded by the CPAN::has_inst() routine
         gzip               location of external program gzip
         histfile           file(1,n) to maintain history(1,3,n,1 builtins) between sessions
         histsize           maximum number of lines to keep in(1,8) histfile
         inactivity_timeout breaks interactive Makefile.PLs after this
                            many seconds inactivity. Set to 0 to never break.
                            if(3,n) true, does not print the startup message
         keep_source_where  directory in(1,8) which to keep the source (if(3,n) 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(3,n) 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(3,n) 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(7,n,1 builtins) and query each of these options interactively in(1,8) the cpan
       shell with the command set(7,n,1 builtins) defined within the "o conf(3,5)" command:

       "o conf(3,5) <scalar option>"
         prints the current value of the scalar option

       "o conf(3,5) <scalar option> <value>"
         Sets the value of the scalar option to value

       "o conf(3,5) <list option>"
         prints the current value of the list option in(1,8) MakeMaker's neatvalue

       "o conf(3,5) <list option> [shift|pop]"
         shifts or pops the array in(1,8) the list option variable

       "o conf(3,5) <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(3,n) your URL is not compliant, but if(3,n) you have problems with
       file(1,n) URLs, please try the correct format. Either:




       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(1,n)" URLs, CPAN always tries to get files from there first. This fea-
       ture is disabled for index files. So the recommendation for the owner
       of a CD-ROM with CPAN contents is: include your local, possibly out-
       dated CD-ROM as a "file(1,n)" URL at the end of urllist, e.g.

         o conf(3,5) urllist push file://localhost/CDROM/CPAN will then fetch the index files from one of the CPAN sites that
       come at the beginning of urllist. It will later check for each module
       if(3,n) there is a local copy of the most recent version.

       Another peculiarity of urllist is that the site that we could success-
       fully fetch the last file(1,n) from automatically gets(3,n) a preference token
       and is tried as the first site for the next request. So if(3,n) you add a
       new site at runtime it may happen that the previously preferred site
       will be tried another time. This means that if(3,n) you want to disallow a
       site for the next transfer, it must be explicitly removed from urllist.

       There's no strong security layer in(1,8) 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(1,n)
       itself. If somebody has managed to tamper with the distribution file(1,n),
       they may have as well tampered with the CHECKSUMS file. Future develop-
       ment will go towards strong authentication.

       Most functions in(1,8) package CPAN are exported per default. The reason for
       this is that the primary use is intended for the cpan shell or for

       Populating a freshly installed perl with my favorite modules is pretty
       easy if(3,n) you maintain a private bundle definition file. To get a useful
       blueprint of a bundle definition file(1,n), the command autobundle can be
       used on the CPAN shell command line. This command writes a bundle defi-
       nition file(1,n) for all modules that are installed for the currently run-
       ning perl interpreter. It's recommended to run this command only once
       and from then on maintain the file(1,n) manually under a private name, say
       Bundle/ With a clever bundle file(1,n) 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(1,n) means keeping track of two things:
       dependencies and interactivity. sometimes fails on calculating
       dependencies because not all modules define all MakeMaker attributes
       correctly, so a bundle definition file(1,n) 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(1,8) my private bundle file(1,n) is to have the packages that need
       to be configured early in(1,8) the file(1,n) and the gentle ones later, so I can
       go out after a few minutes and leave untended.

       Thanks to Graham Barr for contributing the following paragraphs about
       the interaction between perl, and various 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(2,8), 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(2,5)
           the outside world you must do it via the web server. If you set(7,n,1 builtins)
           environment variables like http_proxy or ftp_proxy to a values
           beginning with http:// or in(1,8) your web browser you have to set(7,n,1 builtins) proxy
           information then you know you are running an http firewall.

           To access(2,5) 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(2,5) ftp servers outside the firewall.
           This is usually done by connecting to the firewall with ftp, then
           entering a username like ""

           To access(2,5) 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(1,8,3 Search::Dict) invisible to the users(1,5) inside the firewall. An FTP data con-
           nection 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(1,8) 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(1,2) 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(3,n) it is not

           IP Masquerade
               This is the firewall implemented in(1,8) the Linux kernel, it allows
               you to hide a complete network behind one IP address. With this
               firewall no special compiling is needed as you can access(2,5) hosts

               For accessing ftp servers behind such firewalls you may need to
               set(7,n,1 builtins) the environment variable "FTP_PASSIVE" to a true value,

                   env(1,3) 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, presumably with a
       command such as

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

       then you would configure with the command

           o conf(3,5) lynx "/usr/local/bin/lynx -pscott:tiger"

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

           o conf(3,5) ncftp "/usr/bin/ncftp -f /home/scott/ncftplogin.cfg"

       Your mileage may vary...

       1)  I installed a new version(1,3,5) of module X but CPAN keeps saying, I have
           the old version(1,3,5) installed

           Most probably you do have the old version(1,3,5) installed. This can hap-
           pen if(3,n) a module installs itself into a different directory in(1,8) the
           @INC path than it was previously installed. This is not really a
  problem, you would have the same problem when installing
           the module manually. The easiest way to prevent this behaviour is
           to add the argument "UNINST=1" to the "make install" call, and that
           is why many people add this argument permanently by configuring

             o conf(3,5) make_install_arg UNINST=1

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

           Because there are people who have their precise expectations about
           who may install where in(1,8) the @INC path and who uses which @INC
           array. In fine tuned environments "UNINST=1" can cause damage.

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

           Run the autobundle command for your old perl and optionally rename(1,2,n)
           the resulting bundle file(1,n) (e.g. Bundle/, install the
           new perl with the Configure option prefix, e.g.

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

           Install the bundle file(1,n) you produced in(1,8) the first step with some-
           thing like

               cpan> install Bundle::mybundle

           and you're done.

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

           You may want to configure something like

             o conf(3,5) make_arg "| tee -ai /root/.cpan/logs/make.out"
             o conf(3,5) make_install_arg "| tee -ai /root/.cpan/logs/make_install.out"

           so that STDOUT is captured in(1,8) a file(1,n) for later inspection.

       5)  I am not root, how can I install a module in(1,8) a personal directory?

           You will most probably like something like this:

             o conf(3,5) makepl_arg "LIB=~/myperl/lib \
                               INSTALLMAN1DIR=~/myperl/man(1,5,7)/man1 \
             install Sybase::Sybperl

           You can make this setting permanent like all "o conf(3,5)" settings with
           "o conf(3,5) commit".

           You will have to add ~/myperl/man(1,5,7) to the MANPATH environment vari-
           able and also tell your perl programs to look(1,8,3 Search::Dict) 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(1,8) mind is that the UNINST parameter
           should never be set(7,n,1 builtins) if(3,n) you are not root.

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

             look(1,8,3 Search::Dict) 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(1,8) the generated Make-
           file. 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 every-
           thing. Please note, does not know the dependency tree in(1,8)
           advance and cannot sort(1,3) the queue(1,3) of things to install in(1,8) a topo-
           logically 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(1,3) the Bundle definition file(1,n) manually. It is
           planned to improve the metadata situation for dependencies on CPAN
           in(1,8) 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 but without uploading the mod-
           ules to CPAN?

           Have a look(1,8,3 Search::Dict) at the CPAN::Site module.

       9)  When I run CPAN's shell, I get error(8,n) msg about line 1 to 4, setting
           meta input/output via the /etc/inputrc file.

           Some versions of readline are picky about capitalization in(1,8) the
           /etc/inputrc file(1,n) and specifically RedHat 6.2 comes with a
           /etc/inputrc that contains the word "on" in(1,8) lowercase. Change the
           occurrences of "on" to "On" and the bug should disappear.

       10) Some authors have strange characters in(1,8) their names.

           Internally uses the UTF-8 charset. If your terminal is
           expecting ISO-8859-1 charset, a converter can be activated by set-
           ting term_is_latin to a true value in(1,8) your config(1,5) 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.

       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 tradi-
       tional method of building a Perl module package from a shell.

       Andreas Koenig <>

       Kawai,Takanori provides a Japanese translation of this manpage at

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

perl v5.8.5                       2001-09-21                           CPAN(3)

References for this manual (incoming links)