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CPAN(3)
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
DESCRIPTION
The CPAN module is designed to automate the make and install of perl
modules and extensions. It includes some 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 handling of sets of related modules. See
Bundles below.
The package contains a session manager and a cache manager. There is no
status retained between sessions. The session manager keeps track of what
has been fetched, built and installed in the current session. The cache
manager keeps track of the disk space occupied by the make processes and
deletes excess space according to a simple FIFO mechanism.
For extended searching capabilities there's a plugin for CPAN available,
"CPAN::WAIT". "CPAN::WAIT" is a full-text search engine that indexes all
documents available in CPAN authors directories. If "CPAN::WAIT" is
installed on your system, the interactive shell of CPAN.pm will enable the
"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 mentioned
four. Each of the four entities is implemented as a class with slightly
differing methods for displaying an object.
Arguments you pass to these commands are either strings exactly matching
the identification string of an object or regular expressions that are
then matched case-insensitively against various attributes of the
objects. The parser recognizes a regular expression only if you enclose
it between two slashes.
The principle is that the number of found objects influences how an item
is displayed. If the search finds one item, the result is displayed with
the rather verbose method "as_string", but if 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
prerequisites_policy.)
Any "make" or "test" are run unconditionally. An
install <distribution_file>
also is run unconditionally. But for
install <module>
CPAN checks if an install is actually needed for it and prints module up
to date in the case that the distribution file containing the module
doesn't need to be updated.
CPAN also keeps track of what it has done within the current session and
doesn't try to build a package a second time regardless if it succeeded
or not. The "force" command takes as a first argument the method to
invoke (currently: "make", "test", or "install") and executes the command
from scratch.
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::Config->{cpan_home}/Bundle" directory. The file contains a list of
all modules that are both available from CPAN and currently installed
within @INC. The name of the bundle file is based on the current date and a
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 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.
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 single
polymorphism is in effect. A metaclass object registers all objects of all
kinds and indexes them with a string. The strings referencing objects have
a separated namespace (well, not completely separated):
Namespace Class
words containing a "/" (slash) Distribution
words starting with Bundle:: Bundle
everything else Module or Author
Modules know their associated Distribution objects. They always refer to
the most recent official release. Developers may mark their releases as
unstable development versions (by inserting an underbar into the visible
version number), so the really hottest and newest distribution file 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 distribution file resides on CPAN
relative to the authors/id/ directory. If the author is BAR, this might be
BAR/Foo-1.23_90.tar.gz; so you would have to say
install BAR/Foo-1.23_90.tar.gz
The first example will be driven by an object of the class CPAN::Module,
the second by an object of class CPAN::Distribution.
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 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 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 $mod->uptodate;
# new mod_perl arrived, let me know all update recommendations
CPAN::Shell->r;
Methods in the other Classes
The programming interface for the classes CPAN::Module, CPAN::Distribution,
CPAN::Bundle, and CPAN::Author is still considered beta and partially even
alpha. In the following paragraphs only those methods are documented that
have proven useful over a longer time and thus are unlikely to change.
CPAN:s0:Author::as_glimpse()
Returns a one-line description of the author
CPAN:s0:Author::as_string()
Returns a multi-line description of the author
CPAN:s0:Author::email()
Returns the author's email address
CPAN:s0:Author::fullname()
Returns the author's name
CPAN:s0:Author::name()
An alias for fullname
CPAN:s0:Bundle::as_glimpse()
Returns a one-line description of the bundle
CPAN:s0:Bundle::as_string()
Returns a multi-line description of the bundle
CPAN:s0:Bundle::clean()
Recursively runs the "clean" method on all items contained in the
bundle.
CPAN:s0:Bundle::contains()
Returns a list of objects' IDs contained in a bundle. The associated
objects may be bundles, modules or distributions.
CPAN::Bundle::force($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 recursively to all
contained objects.
CPAN:s0:Bundle::get()
Recursively runs the "get" method on all items contained in the bundle
CPAN:s0: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:s0:Bundle::inst_version()
Like CPAN::Bundle::inst_file, but returns the $VERSION
CPAN:s0:Bundle::uptodate()
Returns 1 if the bundle itself and all its members are uptodate.
CPAN:s0:Bundle::install()
Recursively runs the "install" method on all items contained in the
bundle
CPAN:s0:Bundle::make()
Recursively runs the "make" method on all items contained in the bundle
CPAN:s0:Bundle::readme()
Recursively runs the "readme" method on all items contained in the
bundle
CPAN:s0:Bundle::test()
Recursively runs the "test" method on all items contained in the bundle
CPAN:s0:Distribution::as_glimpse()
Returns a one-line description of the distribution
CPAN:s0:Distribution::as_string()
Returns a multi-line description of the distribution
CPAN:s0:Distribution::clean()
Changes to the directory where the distribution has been unpacked and
runs "make clean" there.
CPAN:s0:Distribution::containsmods()
Returns a list of IDs of modules contained in a distribution file.
Only works for distributions listed in the 02packages.details.txt.gz
file. This typically means that only the most recent version of a
distribution is covered.
CPAN:s0: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:s0:Distribution::dir()
Returns the directory into which this distribution has been unpacked.
CPAN::Distribution::force($method,@args)
Forces CPAN to perform a task that normally would have failed. Force
takes as arguments a method name to be called and any number of
additional arguments that should be passed to the called method. The
internals of the object get the needed changes so that CPAN.pm does not
refuse to take the action.
CPAN:s0:Distribution::get()
Downloads the distribution from CPAN and unpacks it. Does nothing if
the distribution has already been downloaded and unpacked within the
current session.
CPAN:s0:Distribution::install()
Changes to the directory where the distribution has been unpacked and
runs the external command "make install" there. If "make" has not yet
been run, it will be run first. A "make test" will be issued in any
case and if this fails, the install will be cancelled. The cancellation
can be avoided by letting "force" run the "install" for you.
CPAN:s0:Distribution::isa_perl()
Returns 1 if this distribution file seems to be a perl distribution.
Normally this is derived from the file name only, but the index from
CPAN can contain a hint to achieve a return value of true for other
filenames too.
CPAN:s0:Distribution::look()
Changes to the directory where the distribution has been unpacked and
opens a subshell there. Exiting the subshell returns.
CPAN:s0:Distribution::make()
First runs the "get" method to make sure the distribution is downloaded
and unpacked. Changes to the directory where the distribution has been
unpacked and runs the external commands "perl Makefile.PL" and "make"
there.
CPAN:s0:Distribution::prereq_pm()
Returns the hash reference that has been announced by a distribution as
the PREREQ_PM hash in the Makefile.PL. Note: works only after an
attempt has been made to "make" the distribution. Returns undef
otherwise.
CPAN:s0:Distribution::readme()
Downloads the README file associated with a distribution and runs it
through the pager specified in "$CPAN::Config-"{pager}>.
CPAN:s0:Distribution::test()
Changes to the directory where the distribution has been unpacked and
runs "make test" there.
CPAN:s0:Distribution::uptodate()
Returns 1 if all the modules contained in the distribution are
uptodate. Relies on containsmods.
CPAN:s0:Index::force_reload()
Forces a reload of all indices.
CPAN:s0:Index::reload()
Reloads all indices if they have been read more than
"$CPAN::Config-"{index_expire}> days.
CPAN:s0:InfoObj::dump()
CPAN::Author, CPAN::Bundle, CPAN::Module, and CPAN::Distribution
inherit this method. It prints the data structure associated with an
object. Useful for debugging. Note: the data structure is considered
internal and thus subject to change without notice.
CPAN:s0:Module::as_glimpse()
Returns a one-line description of the module
CPAN:s0:Module::as_string()
Returns a multi-line description of the module
CPAN:s0:Module::clean()
Runs a clean on the distribution associated with this module.
CPAN:s0:Module::cpan_file()
Returns the filename on CPAN that is associated with the module.
CPAN:s0:Module::cpan_version()
Returns the latest version of this module available on CPAN.
CPAN:s0:Module::cvs_import()
Runs a cvs_import on the distribution associated with this module.
CPAN:s0:Module::description()
Returns a 44 chracter description of this module. Only available for
modules listed in The Module List (CPAN/modules/00modlist.long.html or
00modlist.long.txt.gz)
CPAN::Module::force($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:s0:Module::get()
Runs a get on the distribution associated with this module.
CPAN:s0: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:s0:Module::inst_version()
Returns the version number of the module in readable format.
CPAN:s0:Module::install()
Runs an "install" on the distribution associated with this module.
CPAN:s0:Module::look()
Changes to the directory where the distribution assoicated with this
module has been unpacked and opens a subshell there. Exiting the
subshell returns.
CPAN:s0:Module::make()
Runs a "make" on the distribution associated with this module.
CPAN:s0: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 downloaded
within this session, does the equivalent on the downloaded module even
if it is not installed.
CPAN:s0:Module::readme()
Runs a "readme" on the distribution associated with this module.
CPAN:s0:Module::test()
Runs a "test" on the distribution associated with this module.
CPAN:s0:Module::uptodate()
Returns 1 if the module is installed and up-to-date.
CPAN:s0: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 $CPAN::Config->{build_cache} (in MB).
The contents of this cache may be used for later re-installations that you
intend to do manually, but will never be trusted by CPAN itself. This is
due to the fact that the user might use these directories for building
modules on different architectures.
There is another directory ($CPAN::Config->{keep_source_where}) where the
original distribution files are kept. This directory is not covered by the
cache manager and must be controlled by the user. If you choose to have the
same directory as build_dir and as keep_source_where directory, then your
sources will be deleted with the same fifo 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 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 associated with an URL that is
not "ftp:".
If you have neither Net::FTP nor LWP, there is a fallback mechanism
implemented for an external ftp command or for an external lynx command.
Finding packages and VERSION
This module presumes that all packages on CPAN
· declare their $VERSION variable in an easy to parse manner. This
prerequisite can hardly be relaxed because it consumes far too much
memory to load all packages into the running program just to determine
the $VERSION variable. Currently all programs that are dealing with
version use something like this
perl -MExtUtils::MakeMaker -le \
'print MM->parse_version(shift)' filename
If you are author of a package and wonder if your $VERSION can be parsed,
please try the above method.
· come as compressed or gzipped tarfiles or as zip files and contain a
Makefile.PL (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 consider working with file: URLs. Of
course, you have to collect your modules somewhere first. So you might use
CPAN.pm to put together all you need on a networked machine. Then copy the
$CPAN::Config->{keep_source_where} (but not $CPAN::Config->{build_dir})
directory on a floppy. This floppy is kind of a personal CPAN. CPAN.pm on
the non-networked machines works nicely with this floppy. See also below
the paragraph about CD-ROM support.
CONFIGURATION
When the CPAN module is installed, a site wide configuration file is
created as CPAN/Config.pm. The default values defined there can be
overridden in another configuration file: CPAN/MyConfig.pm. You can store
this file in $HOME/.cpan/CPAN/MyConfig.pm if you want, because $HOME/.cpan
is added to the search path of the CPAN module before the use() or
require() statements.
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
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 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 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 development 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
oneliners.
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 definition file for all
modules that are installed for the currently running perl interpreter. It's
recommended to run this command only once and from then on maintain the
file manually under a private name, say Bundle/my_bundle.pm. With a clever
bundle file you can then simply say
cpan> install Bundle::my_bundle
then answer a few questions and then go out for a coffee.
Maintaining a bundle definition file means keeping track of two things:
dependencies and interactivity. CPAN.pm 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 a 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 a 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 themselve look
invisible to the users inside the firewall. An FTP data connection is
normally created by sending the remote server your IP address and then
listening for the connection. But the remote server will not be able to
connect to you because of the firewall. So for these types of firewall
FTP connections need to be done in a passive mode.
There are two that I can think off.
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.
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 milage 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 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 something
like
cpan> install Bundle::mybundle
and you're done.
4) When I install bundles or multiple modules with one command there is
too much output to keep track of.
You may want to configure something like
o conf make_arg "| tee -ai /root/.cpan/logs/make.out"
o conf make_install_arg "| tee -ai /root/.cpan/logs/make_install.out"
so that STDOUT is captured in a file for later inspection.
5) I am not root, how can I install a module in a personal directory?
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 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
undetected missing piece breaks the process. But it may well be that
your Bundle installs some prerequisite later than some depending item
and thus your second try is able to resolve everything. Please note,
CPAN.pm does not know the dependency tree in advance and cannot sort
the queue of things to install in a topologically correct order. It
resolves perfectly well IFF all modules declare the prerequisites
correctly with the PREREQ_PM attribute to MakeMaker. For bundles which
fail and you need to install often, it is recommended sort the Bundle
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 modules
to CPAN?
Have a look at the CPAN::Site module.
9) When I run CPAN's shell, I get error msg about line 1 to 4, setting
meta input/output via the /etc/inputrc file.
Some versions of readline are picky about capitalization in the
/etc/inputrc file and specifically RedHat 6.2 comes with a /etc/inputrc
that contains the word "on" in lowercase. Change the occurrences of
"on" to "On" and the bug should disappear.
10) Some authors have strange characters in their names.
Internally CPAN.pm uses the UTF-8 charset. If your 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.
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:\fIs0:Nox(3)
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