/usr/man2/cat.3/CPAN.3.Z(/usr/man2/cat.3/CPAN.3.Z)
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. 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 CPAN.pm, you prob-
ably 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 capabili-
ties 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 (Comprehen-
sive Perl Archive Network) sites and unpacked in a dedicated directory.
The CPAN module also supports the concept of named 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 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 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 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::ReadLine to enjoy both history and
command completion.
Once you are on the command line, type 'h' and the rest should be
self-explanatory.
The function call "shell" takes two optional arguments, one is the
prompt, the second is the default initial command line (the latter only
works if a real ReadLine interface module is installed).
The most common uses of the interactive modes are
Searching for authors, bundles, distribution files and modules
There are corresponding one-letter commands "a", "b", "d", and "m"
for each of the four categories and another, "i" for any of the 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 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 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 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 investigate what is
necessary to perform the action. If the argument is a distribution
file name (recognized by embedded slashes), it is processed. If it is
a module, CPAN determines the distribution file in which this module
is included and processes that, following any dependencies named in
the module's Makefile.PL (this behavior is controlled by prerequi-
sites_policy.)
Any "make" or "test" are run unconditionally. An
install <distribution_file>
also is run unconditionally. But for
install <module>
CPAN checks if an install is actually needed for it and prints module
up to date in the case that the distribution file containing the 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 regardless if 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.
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 associated distribution. "Look" gets
and untars (if not yet done) the distribution file, changes to the
appropriate directory and opens a subshell process in that directory.
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.
Signals
CPAN.pm installs signal handlers for SIGINT and SIGTERM. While you
are in the cpan-shell it is intended that you can press "^C" anytime
and return to the cpan-shell prompt. A SIGTERM will cause the cpan-
shell to clean up and leave the shell loop. You can emulate the
effect of a SIGTERM by sending two consecutive SIGINTs, which usually
means by pressing "^C" twice.
CPAN.pm ignores a SIGPIPE. If the user sets inactivity_timeout, a
SIGALRM is used during the run of the "perl Makefile.PL" subprocess.
CPAN::Shell
The commands that are available in the shell interface are methods in
the package CPAN::Shell. If you enter the shell command, all your input
is split by the Text::ParseWords::shellwords() routine which acts like
most shells do. The first word is being interpreted as the method to be
called and the rest of the words are treated as arguments to this
method. Continuation lines are supported if a line ends with a literal
backslash.
autobundle
"autobundle" writes a bundle file into the "$CPAN::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 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
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 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.
The four "CPAN::*" Classes: Author, Bundle, Module, Distribution
Although it may be considered internal, the class hierarchy does matter
for both users and programmer. CPAN.pm deals with above mentioned four
classes, and all those classes share a set of methods. A classical sin-
gle polymorphism is in effect. A metaclass object registers all objects
of all kinds and indexes them with a string. The strings referencing
objects have a separated namespace (well, not completely separated):
Namespace Class
words containing a "/" (slash) Distribution
words starting with Bundle:: Bundle
everything else Module or Author
Modules know their associated Distribution objects. They always refer
to the most recent official release. Developers may mark their releases
as unstable development versions (by inserting an underbar into the
module version number which will also be reflected in the distribution
name when you run 'make dist'), so the really hottest and newest dis-
tribution is not always the default. If a module Foo circulates on
CPAN in both version 1.23 and 1.23_90, CPAN.pm offers a convenient way
to install version 1.23 by saying
install Foo
This would install the complete distribution file (say
BAR/Foo-1.23.tar.gz) with all accompanying material. But if you would
like to install version 1.23_90, you need to know where the distribu-
tion 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::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
the calling package ("install(...)").
There's currently only one class that has a stable interface -
CPAN::Shell. All commands that are available in the CPAN shell are
methods of the class CPAN::Shell. Each of the commands that produce
listings of modules ("r", "autobundle", "u") also return a list of the
IDs of all modules within the list.
expand($type,@things)
The IDs of all objects available within a program are strings that
can be expanded to the corresponding real objects with the
"CPAN::Shell->expand("Module",@things)" method. Expand returns a list
of CPAN::Module objects according to the @things arguments given. In
scalar context it only returns the first element of the list.
expandany(@things)
Like expand, but returns objects of the appropriate type, i.e.
CPAN::Bundle objects for bundles, CPAN::Module objects for modules
and CPAN::Distribution objects fro distributions.
Programming Examples
This enables the programmer to do operations that combine functional-
ities 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?
If you prefer to do it more in a programmer style in one single
process, maybe something like this suits you better:
# list all modules on my disk that have newer versions on CPAN
for $mod (CPAN::Shell->expand("Module","/./")){
next unless $mod->inst_file;
next if $mod->uptodate;
printf "Module %s is installed as %s, could be updated to %s from CPAN\n",
$mod->id, $mod->inst_version, $mod->cpan_version;
}
If that gives you too much output every day, you maybe only want to
watch for three modules. You can write
for $mod (CPAN::Shell->expand("Module","/Apache|LWP|CGI/")){
as the first line instead. Or you can combine some of the above
tricks:
# watch only for a new mod_perl module
$mod = CPAN::Shell->expand("Module","mod_perl");
exit if $mod->uptodate;
# new mod_perl arrived, let me know all update recommendations
CPAN::Shell->r;
Methods in the other Classes
The programming interface for the classes CPAN::Module, CPAN::Distribu-
tion, CPAN::Bundle, and CPAN::Author is still considered beta and par-
tially even alpha. In the following paragraphs only those methods are
documented that have proven useful over a longer time and thus are
unlikely to change.
CPAN::Author::as_glimpse()
Returns a one-line description of the author
CPAN::Author::as_string()
Returns a multi-line description of the author
CPAN::Author::email()
Returns the author's email address
CPAN::Author::fullname()
Returns the author's name
CPAN::Author::name()
An alias for fullname
CPAN::Bundle::as_glimpse()
Returns a one-line description of the bundle
CPAN::Bundle::as_string()
Returns a multi-line description of the bundle
CPAN::Bundle::clean()
Recursively runs the "clean" method on all items contained in the
bundle.
CPAN::Bundle::contains()
Returns a list of objects' IDs contained in a bundle. The associ-
ated objects may be bundles, modules or distributions.
CPAN::Bundle::force($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 recur-
sively to all contained objects.
CPAN::Bundle::get()
Recursively runs the "get" method on all items contained in the
bundle
CPAN::Bundle::inst_file()
Returns the highest installed version of the bundle in either @INC
or "$CPAN::Config-"{cpan_home}>. Note that this is different from
CPAN::Module::inst_file.
CPAN::Bundle::inst_version()
Like CPAN::Bundle::inst_file, but returns the $VERSION
CPAN::Bundle::uptodate()
Returns 1 if the bundle itself and all its members are uptodate.
CPAN::Bundle::install()
Recursively runs the "install" method on all items contained in the
bundle
CPAN::Bundle::make()
Recursively runs the "make" method on all items contained in the
bundle
CPAN::Bundle::readme()
Recursively runs the "readme" method on all items contained in the
bundle
CPAN::Bundle::test()
Recursively runs the "test" method on all items contained in the
bundle
CPAN::Distribution::as_glimpse()
Returns a one-line description of the distribution
CPAN::Distribution::as_string()
Returns a multi-line description of the distribution
CPAN::Distribution::clean()
Changes to the directory where the distribution has been unpacked
and runs "make clean" there.
CPAN::Distribution::containsmods()
Returns a list of IDs of modules contained in a distribution file.
Only works for distributions listed in the 02pack-
ages.details.txt.gz file. This typically means that only the most
recent version of a distribution is covered.
CPAN::Distribution::cvs_import()
Changes to the directory where the distribution has been unpacked
and runs something like
cvs -d $cvs_root import -m $cvs_log $cvs_dir $userid v$version
there.
CPAN::Distribution::dir()
Returns the directory into which this distribution has been
unpacked.
CPAN::Distribution::force($method,@args)
Forces CPAN to perform a task that normally would have failed.
Force takes as arguments a method name to be called and any number
of additional arguments that should be passed to the called method.
The internals of the object get the needed changes so that CPAN.pm
does not refuse to take the action.
CPAN::Distribution::get()
Downloads the distribution from CPAN and unpacks it. Does nothing
if the distribution has already been downloaded and unpacked within
the current session.
CPAN::Distribution::install()
Changes to the directory where the distribution has been unpacked
and runs the external command "make install" there. If "make" has
not yet been run, it will be run first. A "make test" will be
issued in any case and if this fails, the install will be canceled.
The cancellation can be avoided by letting "force" run the
"install" for you.
CPAN::Distribution::isa_perl()
Returns 1 if this distribution file seems to be a perl distribu-
tion. Normally this is derived from the file name only, but the
index from CPAN can contain a hint to achieve a return value of
true for other filenames too.
CPAN::Distribution::look()
Changes to the directory where the distribution has been unpacked
and opens a subshell there. Exiting the subshell returns.
CPAN::Distribution::make()
First runs the "get" method to make sure the distribution is down-
loaded and unpacked. Changes to the directory where the distribu-
tion has been unpacked and runs the external commands "perl Make-
file.PL" and "make" there.
CPAN::Distribution::prereq_pm()
Returns the hash reference that has been announced by a distribu-
tion as the PREREQ_PM hash in the Makefile.PL. Note: works only
after an attempt has been made to "make" the distribution. Returns
undef otherwise.
CPAN::Distribution::readme()
Downloads the README file associated with a distribution and runs
it through the pager specified in "$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 distribution are
uptodate. Relies on containsmods.
CPAN::Index::force_reload()
Forces a reload of all indices.
CPAN::Index::reload()
Reloads all indices if they have been read more than "$CPAN::Con-
fig-"{index_expire}> days.
CPAN::InfoObj::dump()
CPAN::Author, CPAN::Bundle, CPAN::Module, and CPAN::Distribution
inherit this method. It prints the data structure associated with
an object. Useful for debugging. Note: the data structure is con-
sidered internal and thus subject to change without notice.
CPAN::Module::as_glimpse()
Returns a one-line description of the module
CPAN::Module::as_string()
Returns a multi-line description of the module
CPAN::Module::clean()
Runs a clean on the distribution associated with this module.
CPAN::Module::cpan_file()
Returns the filename on CPAN that is associated with the module.
CPAN::Module::cpan_version()
Returns the latest version of this module available on CPAN.
CPAN::Module::cvs_import()
Runs a cvs_import on the distribution associated with this module.
CPAN::Module::description()
Returns a 44 character description of this module. Only available
for modules listed in The Module List (CPAN/modules/00mod-
list.long.html or 00modlist.long.txt.gz)
CPAN::Module::force($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 associated with
this module has been unpacked and opens a subshell there. Exiting
the subshell returns.
CPAN::Module::make()
Runs a "make" on the distribution associated with this module.
CPAN::Module::manpage_headline()
If module is installed, peeks into the module's manpage, reads the
headline and returns it. Moreover, if the module has been down-
loaded 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 $CPAN::Config->{build_cache} (in
MB). The contents of this cache may be used for later re-installations
that you intend to do manually, but will never be trusted by CPAN
itself. This is due to the fact that the user might use these directo-
ries for building modules on different architectures.
There is another directory ($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.
Bundles
A bundle is just a perl module in the namespace Bundle:: that does not
define any functions or methods. It usually only contains documenta-
tion.
It starts like a perl module with a package declaration and a $VERSION
variable. After that the pod section looks like any other pod with the
only difference being that one special pod section exists starting with
(verbatim):
=head1 CONTENTS
In this pod section each line obeys the format
Module_Name [Version_String] [- optional text]
The only required part is the first field, the name of a module (e.g.
Foo::Bar, ie. not the name of the distribution file). The rest of the
line is optional. The comment part is delimited by a dash just as in
the man page header.
The distribution of a bundle should follow the same convention as other
distributions.
Bundles are treated specially in the CPAN package. If you say 'install
Bundle::Tkkit' (assuming such a bundle exists), CPAN will install all
the modules in the CONTENTS section of the pod. You can install your
own Bundles locally by placing a conformant Bundle file somewhere into
your @INC path. The autobundle() command which is available in the
shell interface does that for you by including all currently installed
modules in a snapshot bundle file.
Prerequisites
If you have a local mirror of CPAN and can access all files with
"file:" URLs, then you only need a perl better than perl5.003 to run
this module. Otherwise Net::FTP is strongly recommended. LWP may be
required for non-UNIX systems or if your nearest CPAN site is 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-
mand.
Finding packages and VERSION
This module presumes that all packages on CPAN
o declare their $VERSION variable in an easy to parse manner. This pre-
requisite can hardly be relaxed because it consumes far too much mem-
ory to load all packages into the running program just to determine
the $VERSION variable. Currently all programs that are dealing with
version use something like this
perl -MExtUtils::MakeMaker -le \
'print MM->parse_version(shift)' filename
If you are author of a package and wonder if your $VERSION can be
parsed, please try the above method.
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 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 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 consider working with file: URLs.
Of course, you have to collect your modules somewhere first. So you
might use CPAN.pm to put together all you need on a networked machine.
Then copy the $CPAN::Config->{keep_source_where} (but not $CPAN::Con-
fig->{build_dir}) directory on a floppy. This floppy is kind of a per-
sonal 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 configuration dialog
tries to determine a couple of site specific options. The result of the
dialog is stored in a hash reference $CPAN::Config in a file CPAN/Con-
fig.pm.
The default values defined in the CPAN/Config.pm file can be overridden
in a user specific file: CPAN/MyConfig.pm. Such a file is best placed
in $HOME/.cpan/CPAN/MyConfig.pm, because $HOME/.cpan is added to the
search path of the CPAN module before the use() or require() state-
ments.
The configuration dialog can be started any time later again by issue-
ing the command " o conf init " in the CPAN shell.
Currently the following keys in the hash reference $CPAN::Config are
defined:
build_cache size of cache for directories to build modules
build_dir locally accessible directory to build modules
index_expire after this many days refetch index files
cache_metadata use serializer to cache metadata
cpan_home local directory reserved for this package
dontload_hash anonymous hash: modules in the keys will not be
loaded by the CPAN::has_inst() routine
gzip location of external program gzip
histfile file to maintain history between sessions
histsize maximum number of lines to keep in histfile
inactivity_timeout breaks interactive Makefile.PLs after this
many seconds inactivity. Set to 0 to never break.
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 MakeMaker's neatvalue
format.
"o conf <list option> [shift|pop]"
shifts or pops the array in the list option variable
"o conf <list option> [unshift|push|splice] <list>"
works like the corresponding perl commands.
Note on urllist parameter's format
urllist parameters are URLs according to RFC 1738. We do a little
guessing if your URL is not compliant, but if you have problems with
file URLs, please try the correct format. 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 contains a list of
URLs that are to be used for downloading. If the list contains any
"file" URLs, CPAN always tries to get files from there first. This 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" 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 success-
fully fetch the last file from automatically gets a preference token
and is tried as the first site for the next request. So if you add a
new site at runtime it may happen that the previously preferred site
will be tried another time. This means that if you want to disallow a
site for the next transfer, it must be explicitly removed from urllist.
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 managed 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. 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 modules is pretty
easy if you maintain a private bundle definition file. To get a useful
blueprint of a bundle definition file, the command autobundle can be
used on the CPAN shell command line. This command writes a bundle defi-
nition file 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 manually under a private name, say
Bundle/my_bundle.pm. With a clever bundle file you can then simply say
cpan> install Bundle::my_bundle
then answer a few questions and then go out for a coffee.
Maintaining a bundle definition file means keeping track of two things:
dependencies and interactivity. CPAN.pm sometimes fails on calculating
dependencies because not all modules define all MakeMaker attributes
correctly, so a bundle definition file should specify prerequisites as
early as possible. On the other hand, it's a bit annoying that many
distributions need some interactive configuring. So what I try to
accomplish in my private bundle file is to have the packages that need
to be configured early in the file and the gentle ones later, so I can
go out after a few minutes and leave CPAN.pm untended.
WORKING WITH CPAN.pm BEHIND FIREWALLS
Thanks to Graham Barr for contributing the following paragraphs about
the interaction between perl, and various firewall configurations. For
further informations on firewalls, it is recommended to consult the
documentation that comes with the ncftp program. If you are unable to
go through the firewall with a simple Perl setup, it is very likely
that you can configure ncftp so that it works for your firewall.
Three basic types of firewalls
Firewalls can be categorized into three basic types.
http firewall
This is where the firewall machine runs a web server and to access
the outside world you must do it via the web server. If you set
environment variables like http_proxy or ftp_proxy to a values
beginning with http:// or in your web browser you have to set proxy
information then you know you are running an http firewall.
To access servers outside these types of firewalls with perl (even
for ftp) you will need to use LWP.
ftp firewall
This where the firewall machine runs an ftp server. This kind of
firewall will only let you access ftp servers outside the firewall.
This is usually done by connecting to the firewall with ftp, then
entering a username like "user@outside.host.com"
To access servers outside these type of firewalls with perl you
will need to use Net::FTP.
One way visibility
I say one way visibility as these firewalls try to make themselves
look invisible to the users inside the firewall. An FTP data 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 a
passive mode.
There are two that I can think off.
SOCKS
If you are using a SOCKS firewall you will need to compile perl
and link it with the SOCKS library, this is what is normally
called a 'socksified' perl. With this executable you will be
able to connect to servers outside the firewall as if it is not
there.
IP Masquerade
This is the firewall implemented in the Linux kernel, it allows
you to hide a complete network behind one IP address. With this
firewall no special compiling is needed as you can access hosts
directly.
For accessing ftp servers behind such firewalls you 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, presumably with a
command such as
/usr/local/bin/lynx -pscott:tiger
then you would configure CPAN.pm with the command
o conf lynx "/usr/local/bin/lynx -pscott:tiger"
That's all. Similarly for ncftp or ftp, you would configure something
like
o conf ncftp "/usr/bin/ncftp -f /home/scott/ncftplogin.cfg"
Your mileage may vary...
FAQ
1) I installed a new version of module X but CPAN keeps saying, I have
the old version installed
Most probably you do have the old version installed. This can hap-
pen if a module installs itself into a different directory in the
@INC path than it was previously installed. This is not really a
CPAN.pm problem, you would have the same problem when installing
the module manually. The easiest way to prevent this behaviour is
to add the argument "UNINST=1" to the "make install" call, and that
is why many people add this argument permanently by configuring
o conf make_install_arg UNINST=1
2) So why is UNINST=1 not the default?
Because there are people who have their precise expectations about
who may install where in the @INC path and who uses which @INC
array. In fine tuned environments "UNINST=1" can cause damage.
3) I want to clean up my mess, and install a new perl along with all
modules I have. How do I go about it?
Run the autobundle command for your old perl and optionally rename
the resulting bundle file (e.g. Bundle/mybundle.pm), install the
new perl with the Configure option prefix, e.g.
./Configure -Dprefix=/usr/local/perl-5.6.78.9
Install the bundle file you produced in the first step with 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 make_arg "| tee -ai /root/.cpan/logs/make.out"
o conf make_install_arg "| tee -ai /root/.cpan/logs/make_install.out"
so that STDOUT is captured in a file for later inspection.
5) I am not root, how can I install a module in a personal directory?
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 environment vari-
able 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 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, CPAN.pm does not know the dependency tree in
advance and cannot sort the queue of things to install in 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 the Bundle definition file manually. 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 mod-
ules to CPAN?
Have a look at the CPAN::Site module.
9) When I run CPAN's shell, I get error msg about line 1 to 4, setting
meta input/output via the /etc/inputrc file.
Some versions of readline are picky about capitalization in the
/etc/inputrc file and specifically RedHat 6.2 comes with a
/etc/inputrc that contains the word "on" in lowercase. Change the
occurrences of "on" to "On" and the bug should disappear.
10) Some authors have strange characters in their names.
Internally CPAN.pm uses the UTF-8 charset. If your terminal is
expecting ISO-8859-1 charset, a converter can be activated by set-
ting 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 tradi-
tional method of building a Perl module package from a shell.
AUTHOR
Andreas Koenig <andreas.koenig@anima.de>
TRANSLATIONS
Kawai,Takanori provides a Japanese translation of this manpage at
http://member.nifty.ne.jp/hippo2000/perltips/CPAN.htm
SEE ALSO
perl(1), CPAN::Nox(3)
perl v5.8.8 2006-06-14 CPAN(3)
See also CPAN::FirstTime(3)
See also CPAN::Nox(3)
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