CPAN(3p) Perl Programmers Reference Guide CPAN(3p)NAMECPAN - 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 compati-
bility. If you're new to CPAN.pm, you probably should inves-
tigate if CPANPLUS is the better choice for you. If you're
already used to CPAN.pm you're welcome to continue using it,
if you accept that its development is mostly (though not
completely) stalled.
DESCRIPTION
The CPAN module is designed to automate the make and install
of perl modules and extensions. It includes some primitive
searching capabilities and knows how to use Net::FTP or LWP
(or lynx or an external ftp client) to fetch the raw data
from the net.
Modules are fetched from one or more of the mirrored CPAN
(Comprehensive Perl Archive Network) sites and unpacked in a
dedicated directory.
The CPAN module also supports the concept of named and ver-
sioned bundles of modules. Bundles simplify the handling of
sets of related modules. See Bundles below.
The package contains a session manager and a cache manager.
There is no status retained between sessions. The session
manager keeps track of what has been fetched, built and
installed in the current session. The cache manager keeps
track of the disk space occupied by the make processes and
deletes excess space according to a simple FIFO mechanism.
For extended searching capabilities there's a plugin for
CPAN available, "CPAN::WAIT". "CPAN::WAIT" is a full-text
search engine that indexes all documents available in CPAN
authors directories. If "CPAN::WAIT" is installed on your
system, the interactive shell of CPAN.pm will enable the
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"wq", "wr", "wd", "wl", and "wh" commands which send queries
to the WAIT server that has been configured for your instal-
lation.
All other methods provided are accessible in a programmer
style and in an interactive shell style.
Interactive Mode
The interactive mode is entered by running
perl -MCPAN -e shell
which puts you into a readline interface. You will have the
most fun if you install Term::ReadKey and Term::ReadLine to
enjoy both history and command completion.
Once you are on the command line, type 'h' and the rest
should be self-explanatory.
The function call "shell" takes two optional arguments, one
is the prompt, the second is the default initial command
line (the latter only works if a real ReadLine interface
module is installed).
The most common uses of the interactive modes are
Searching for authors, bundles, distribution files and modules
There are corresponding one-letter commands "a", "b", "d",
and "m" for each of the four categories and another, "i"
for any of the mentioned four. Each of the four entities
is implemented as a class with slightly differing methods
for displaying an object.
Arguments you pass to these commands are either strings
exactly matching the identification string of an object or
regular expressions that are then matched case-
insensitively against various attributes of the objects.
The parser recognizes a regular expression only if you
enclose it between two slashes.
The principle is that the number of found objects influ-
ences how an item is displayed. If the search finds one
item, the result is displayed with the rather verbose
method "as_string", but if we find more than one, we
display each object with the terse method <as_glimpse>.
make, test, install, clean modules or distributions
These commands take any number of arguments and investi-
gate what is necessary to perform the action. If the argu-
ment is a distribution file name (recognized by embedded
slashes), it is processed. If it is a module, CPANperl v5.8.8 2005-02-05 2
CPAN(3p) Perl Programmers Reference Guide CPAN(3p)
determines the distribution file in which this module is
included and processes that, following any dependencies
named in the module's Makefile.PL (this behavior is con-
trolled by prerequisites_policy.)
Any "make" or "test" are run unconditionally. An
install <distribution_file>
also is run unconditionally. But for
install <module>
CPAN checks if an install is actually needed for it and
prints module up to date in the case that the distribution
file containing the module doesn't need to be updated.
CPAN also keeps track of what it has done within the
current session and doesn't try to build a package a
second time regardless if it succeeded or not. The "force"
command takes as a first argument the method to invoke
(currently: "make", "test", or "install") and executes the
command from scratch.
Example:
cpan> install OpenGL
OpenGL is up to date.
cpan> force install OpenGL
Running make
OpenGL-0.4/
OpenGL-0.4/COPYRIGHT
[...]
A "clean" command results in a
make clean
being executed within the distribution file's working
directory.
get, readme, look module or distribution
"get" downloads a distribution file without further
action. "readme" displays the README file of the associ-
ated distribution. "Look" gets and untars (if not yet
done) the distribution file, changes to the appropriate
directory and opens a subshell process in that directory.
ls author
"ls" lists all distribution files in and below an author's
CPAN directory. Only those files that contain modules are
listed and if there is more than one for any given module,
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only the most recent one is listed.
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 argu-
ments to this method. Continuation lines are supported if a
line ends with a literal backslash.
autobundle
"autobundle" writes a bundle file into the
"$CPAN::Config->{cpan_home}/Bundle" directory. The file con-
tains a list of all modules that are both available from
CPAN and currently installed within @INC. The name of the
bundle file is based on the current date and a counter.
recompile
recompile() is a very special command in that it takes no
argument and runs the make/test/install cycle with brute
force over all installed dynamically loadable extensions
(aka XS modules) with 'force' in effect. The primary purpose
of this command is to finish a network installation. Ima-
gine, you have a common source tree for two different archi-
tectures. You decide to do a completely independent fresh
installation. You start on one architecture with the help of
a Bundle file produced earlier. CPAN installs the whole Bun-
dle for you, but when you try to repeat the job on the
second architecture, CPAN responds with a "Foo up to date"
message for all modules. So you invoke CPAN's recompile on
the second architecture and you're done.
Another popular use for "recompile" is to act as a rescue in
case your perl breaks binary compatibility. If one of the
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modules that CPAN uses is in turn depending on binary compa-
tibility (so you cannot run CPAN commands), then you should
try the CPAN::Nox module for recovery.
The four "CPAN::*" Classes: Author, Bundle, Module, Distri-
bution
Although it may be considered internal, the class hierarchy
does matter for both users and programmer. CPAN.pm deals
with above mentioned four classes, and all those classes
share a set of methods. A classical single polymorphism is
in effect. A metaclass object registers all objects of all
kinds and indexes them with a string. The strings referenc-
ing objects have a separated namespace (well, not completely
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 distribution
is not always the default. If a module Foo circulates on
CPAN in both version 1.23 and 1.23_90, CPAN.pm offers a con-
venient way to install version 1.23 by saying
install Foo
This would install the complete distribution file (say
BAR/Foo-1.23.tar.gz) with all accompanying material. But if
you would like to install version 1.23_90, you need to know
where the distribution file resides on CPAN relative to the
authors/id/ directory. If the author is BAR, this might be
BAR/Foo-1.23_90.tar.gz; so you would have to say
install BAR/Foo-1.23_90.tar.gz
The first example will be driven by an object of the class
CPAN::Module, the second by an object of class
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(...)").
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There's currently only one class that has a stable interface
- CPAN::Shell. All commands that are available in the CPAN
shell are methods of the class CPAN::Shell. Each of the com-
mands that produce listings of modules ("r", "autobundle",
"u") also return a list of the IDs of all modules within the
list.
things)@u-3p expand($type,@things)
The IDs of all objects available within a program are
strings that can be expanded to the corresponding real
objects with the "CPAN::Shell->expand("Module",@things)"
method. Expand returns a list of CPAN::Module objects
according to the @things arguments given. In scalar con-
text it only returns the first element of the list.
things)@u-3p 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 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
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modules are up to date, you can parse the output of above
command for the regular expression //modules are up to
date// and decide to mail the output only if it doesn't
match. Ick?
If you prefer to do it more in a programmer style in one
single process, maybe something like this suits you
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 $mod->uptodate;
# new mod_perl arrived, let me know all update recommendations
CPAN::Shell->r;
Methods in the other Classes
The programming interface for the classes CPAN::Module,
CPAN::Distribution, CPAN::Bundle, and CPAN::Author is still
considered beta and partially even alpha. In the following
paragraphs only those methods are documented that have pro-
ven useful over a longer time and thus are unlikely to
change.
CPAN::Author::as_glimpse()
Returns a one-line description of the author
CPAN::Author::as_string()
Returns a multi-line description of the author
CPAN::Author::email()
Returns the author's email address
CPAN::Author::fullname()
Returns the author's name
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An alias for fullname
CPAN::Bundle::as_glimpse()
Returns a one-line description of the bundle
CPAN::Bundle::as_string()
Returns a multi-line description of the bundle
CPAN::Bundle::clean()
Recursively runs the "clean" method on all items con-
tained in the bundle.
CPAN::Bundle::contains()
Returns a list of objects' IDs contained in a bundle.
The associated objects may be bundles, modules or dis-
tributions.
args)@u-3p CPAN::Bundle::force($method,@args)
Forces CPAN to perform a task that normally would have
failed. Force takes as arguments a method name to be
called and any number of additional arguments that
should be passed to the called method. The internals of
the object get the needed changes so that CPAN.pm does
not refuse to take the action. The "force" is passed
recursively to all contained objects.
CPAN::Bundle::get()
Recursively runs the "get" method on all items 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 con-
tained in the bundle
CPAN::Bundle::make()
Recursively runs the "make" method on all items con-
tained in the bundle
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Recursively runs the "readme" method on all items con-
tained in the bundle
CPAN::Bundle::test()
Recursively runs the "test" method on all items con-
tained 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 distri-
bution file. Only works for distributions listed in the
02packages.details.txt.gz file. This typically means
that only the most recent version of a distribution is
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.
args)@u-3p CPAN::Distribution::force($method,@args)
Forces CPAN to perform a task that normally would have
failed. Force takes as arguments a method name to be
called and any number of additional arguments that
should be passed to the called method. The internals of
the object get the needed changes so that CPAN.pm does
not refuse to take the action.
CPAN::Distribution::get()
Downloads the distribution from CPAN and unpacks it.
Does nothing if the distribution has already been down-
loaded and unpacked within the current session.
CPAN::Distribution::install()
Changes to the directory where the distribution has been
unpacked and runs the external command "make install"
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there. If "make" has not yet been run, it will be run
first. A "make test" will be issued in any case and if
this fails, the install will be canceled. The cancella-
tion can be avoided by letting "force" run the "install"
for you.
CPAN::Distribution::isa_perl()
Returns 1 if this distribution file seems to be a perl
distribution. Normally this is derived from the file
name only, but the index from CPAN can contain a hint to
achieve a return value of true for other filenames too.
CPAN::Distribution::look()
Changes to the directory where the distribution has been
unpacked and opens a subshell there. Exiting the sub-
shell returns.
CPAN::Distribution::make()
First runs the "get" method to make sure the distribu-
tion is downloaded and unpacked. Changes to the direc-
tory where the distribution has been unpacked and runs
the external commands "perl Makefile.PL" and "make"
there.
CPAN::Distribution::prereq_pm()
Returns the hash reference that has been announced by a
distribution as the PREREQ_PM hash in the Makefile.PL.
Note: works only after an attempt has been made to
"make" the distribution. Returns undef otherwise.
CPAN::Distribution::readme()
Downloads the README file associated with a distribution
and runs it through the pager specified in
"$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 distribu-
tion are uptodate. Relies on containsmods.
CPAN::Index::force_reload()
Forces a reload of all indices.
CPAN::Index::reload()
Reloads all indices if they have been read more than
"$CPAN::Config-"{index_expire}> days.
CPAN::InfoObj::dump()
CPAN::Author, CPAN::Bundle, CPAN::Module, and
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CPAN::Distribution inherit this method. It prints the
data structure associated with an object. Useful for
debugging. Note: the data structure is considered inter-
nal and thus subject to change without notice.
CPAN::Module::as_glimpse()
Returns a one-line description of the module
CPAN::Module::as_string()
Returns a multi-line description of the module
CPAN::Module::clean()
Runs a clean on the distribution associated with this
module.
CPAN::Module::cpan_file()
Returns the filename on CPAN that is associated with the
module.
CPAN::Module::cpan_version()
Returns the latest version of this module available on
CPAN.
CPAN::Module::cvs_import()
Runs a cvs_import on the distribution associated with
this module.
CPAN::Module::description()
Returns a 44 character description of this module. Only
available for modules listed in The Module List
(CPAN/modules/00modlist.long.html or
00modlist.long.txt.gz)
args)@u-3p CPAN::Module::force($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
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format.
CPAN::Module::install()
Runs an "install" on the distribution associated with
this module.
CPAN::Module::look()
Changes to the directory where the distribution associ-
ated with this module has been unpacked and opens a sub-
shell there. Exiting the subshell returns.
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 downloaded within this session, does the
equivalent on the downloaded module even if it is not
installed.
CPAN::Module::readme()
Runs a "readme" on the distribution associated with this
module.
CPAN::Module::test()
Runs a "test" on the distribution associated with this
module.
CPAN::Module::uptodate()
Returns 1 if the module is installed and up-to-date.
CPAN::Module::userid()
Returns the author's ID of the module.
Cache Manager
Currently the cache manager only keeps track of the build
directory ($CPAN::Config->{build_dir}). It is a simple FIFO
mechanism that deletes complete directories below
"build_dir" as soon as the size of all directories there
gets bigger than $CPAN::Config->{build_cache} (in MB). The
contents of this cache may be used for later re-
installations that you intend to do manually, but will never
be trusted by CPAN itself. This is due to the fact that the
user might use these directories for building modules on
different architectures.
There is another directory
($CPAN::Config->{keep_source_where}) where the original dis-
tribution files are kept. This directory is not covered by
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the cache manager and must be controlled by the user. If you
choose to have the same directory as build_dir and as
keep_source_where directory, then your sources will be
deleted with the same fifo mechanism.
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 spe-
cial pod section exists starting with (verbatim):
=head1 CONTENTS
In this pod section each line obeys the format
Module_Name [Version_String] [- optional text]
The only required part is the first field, the name of a
module (e.g. Foo::Bar, ie. not the name of the distribution
file). The rest of the line is optional. The comment part is
delimited by a dash just as in the man page header.
The distribution of a bundle should follow the same conven-
tion as other distributions.
Bundles are treated specially in the CPAN package. If you
say 'install Bundle::Tkkit' (assuming such a bundle exists),
CPAN will install all the modules in the CONTENTS section of
the pod. You can install your own Bundles locally by placing
a conformant Bundle file somewhere into your @INC path. The
autobundle() command which is available in the shell inter-
face does that for you by including all currently installed
modules in a snapshot bundle file.
Prerequisites
If you have a local mirror of CPAN and can access all files
with "file:" URLs, then you only need a perl better than
perl5.003 to run this module. Otherwise Net::FTP is strongly
recommended. LWP may be required for non-UNIX systems or if
your nearest CPAN site is associated with a URL that is not
"ftp:".
If you have neither Net::FTP nor LWP, there is a fallback
mechanism implemented for an external ftp command or for an
external lynx command.
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Finding packages and VERSION
This module presumes that all packages on CPAN
+ declare their $VERSION variable in an easy to parse
manner. This prerequisite can hardly be relaxed because it
consumes far too much memory to load all packages into the
running program just to determine the $VERSION variable.
Currently all programs that are dealing with version use
something like this
perl -MExtUtils::MakeMaker -le \
'print MM->parse_version(shift)' filename
If you are author of a package and wonder if your $VERSION
can be parsed, please try the above method.
+ come as compressed or gzipped tarfiles or as zip files and
contain a Makefile.PL (well, we try to handle a bit more,
but without much enthusiasm).
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 com-
pletion support.
For data debugging there is the "dump" command which takes
the same arguments as make/test/install and outputs the
object's Data::Dumper dump.
Floppy, Zip, Offline Mode
CPAN.pm works nicely without network too. If you maintain
machines that are not networked at all, you should consider
working with file: URLs. Of course, you have to collect your
modules somewhere first. So you might use CPAN.pm to put
together all you need on a networked machine. Then copy the
$CPAN::Config->{keep_source_where} (but not
$CPAN::Config->{build_dir}) directory on a floppy. This
floppy is kind of a personal CPAN. CPAN.pm on the non-
networked machines works nicely with this floppy. See also
below the paragraph about CD-ROM support.
CONFIGURATION
When the CPAN module is used for the first time, a
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configuration dialog tries to determine a couple of site
specific options. The result of the dialog is stored in a
hash reference $CPAN::Config in a file CPAN/Config.pm.
The default values defined in the CPAN/Config.pm file can be
overridden in a user specific file: CPAN/MyConfig.pm. Such a
file is best placed in $HOME/.cpan/CPAN/MyConfig.pm, because
$HOME/.cpan is added to the search path of the CPAN module
before the use() or require() statements.
The configuration dialog can be started any time later again
by issueing the command " o conf init " in the CPAN shell.
Currently the following keys in the hash reference
$CPAN::Config are defined:
build_cache size of cache for directories to build modules
build_dir locally accessible directory to build modules
index_expire after this many days refetch index files
cache_metadata use serializer to cache metadata
cpan_home local directory reserved for this package
dontload_hash anonymous hash: modules in the keys will not be
loaded by the CPAN::has_inst() routine
gzip location of external program gzip
histfile file to maintain history between sessions
histsize maximum number of lines to keep in histfile
inactivity_timeout breaks interactive Makefile.PLs after this
many seconds inactivity. Set to 0 to never break.
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.
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You can set and query each of these options interactively in
the cpan shell with the command set defined within the "o
conf" command:
"o conf <scalar option>"
prints the current value of the scalar option
"o conf <scalar option> <value>"
Sets the value of the scalar option to value
"o conf <list option>"
prints the current value of the list option in MakeMaker's
neatvalue format.
"o conf <list option> [shift|pop]"
shifts or pops the array in the list option variable
"o conf <list option> [unshift|push|splice] <list>"
works like the corresponding perl commands.
Note on urllist parameter's format
urllist parameters are URLs according to RFC 1738. We do a
little guessing if your URL is not compliant, but if you
have problems with file URLs, please try the correct format.
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
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gets a preference token and is tried as the first site for
the next request. So if you add a new site at runtime it may
happen that the previously preferred site will be tried
another time. This means that if you want to disallow a site
for the next transfer, it must be explicitly removed from
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 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 definition file for all
modules that are installed for the currently running perl
interpreter. It's recommended to run this command only once
and from then on maintain the file manually under a private
name, say Bundle/my_bundle.pm. With a clever bundle file you
can then simply say
cpan> install Bundle::my_bundle
then answer a few questions and then go out for a coffee.
Maintaining a bundle definition file means keeping track of
two things: dependencies and interactivity. CPAN.pm some-
times fails on calculating dependencies because not all
modules define all MakeMaker attributes correctly, so a bun-
dle definition file should specify prerequisites as early as
possible. On the other hand, it's a bit annoying that many
distributions need some interactive configuring. So what I
try to accomplish in my private bundle file is to have the
packages that need to be configured early in the file and
the gentle ones later, so I can go out after a few minutes
and leave CPAN.pm untended.
WORKING WITH CPAN.pm BEHIND FIREWALLS
Thanks to Graham Barr for contributing the following para-
graphs about the interaction between perl, and various
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firewall configurations. For further informations on
firewalls, it is recommended to consult the documentation
that comes with the ncftp program. If you are unable to go
through the firewall with a simple Perl setup, it is very
likely that you can configure ncftp so that it works for
your firewall.
Three basic types of firewalls
Firewalls can be categorized into three basic types.
http firewall
This is where the firewall machine runs a web server and
to access the outside world you must do it via the web
server. If you set environment variables like http_proxy
or ftp_proxy to a values beginning with http:// or in
your web browser you have to set proxy information then
you know you are running an http firewall.
To access servers outside these types of firewalls with
perl (even for ftp) you will need to use LWP.
ftp firewall
This where the firewall machine runs an ftp server. This
kind of firewall will only let you access ftp servers
outside the firewall. This is usually done by connecting
to the firewall with ftp, then entering a username like
"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 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
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This is the firewall implemented in the Linux ker-
nel, it allows you to hide a complete network behind
one IP address. With this firewall no special com-
piling is needed as you can access hosts directly.
For accessing ftp servers behind such firewalls you
may need to set the environment variable
"FTP_PASSIVE" to a true value, e.g.
env FTP_PASSIVE=1 perl -MCPAN -eshell
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, presum-
ably with a command such as
/usr/local/bin/lynx -pscott:tiger
then you would configure CPAN.pm with the command
o conf lynx "/usr/local/bin/lynx -pscott:tiger"
That's all. Similarly for ncftp or ftp, you would configure
something like
o conf ncftp "/usr/bin/ncftp -f /home/scott/ncftplogin.cfg"
Your mileage may vary...
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 dif-
ferent directory in the @INC path than it was previously
installed. This is not really a CPAN.pm problem, you
would have the same problem when installing the module
manually. The easiest way to prevent this behaviour is
to add the argument "UNINST=1" to the "make install"
call, and that is why many people add this argument per-
manently by configuring
o conf make_install_arg UNINST=1
2) So why is UNINST=1 not the default?
Because there are people who have their precise
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expectations about who may install where in the @INC
path and who uses which @INC array. In fine tuned
environments "UNINST=1" can cause damage.
3) I want to clean up my mess, and install a new perl along
with all modules I have. How do I go about it?
Run the autobundle command for your old perl and option-
ally rename the resulting bundle file (e.g.
Bundle/mybundle.pm), install the new perl with the Con-
figure option prefix, e.g.
./Configure -Dprefix=/usr/local/perl-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 com-
mand there is too much output to keep track of.
You may want to configure something like
o conf make_arg "| tee -ai /root/.cpan/logs/make.out"
o conf make_install_arg "| tee -ai /root/.cpan/logs/make_install.out"
so that STDOUT is captured in a file for later inspec-
tion.
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.
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Another thing you should bear in mind is that the UNINST
parameter should never be set if you are not root.
6) How to get a package, unwrap it, and make a change
before building it?
look Sybase::Sybperl
7) I installed a Bundle and had a couple of fails. When I
retried, everything resolved nicely. Can this be fixed
to work on first try?
The reason for this is that CPAN does not know the
dependencies of all modules when it starts out. To
decide about the additional items to install, it just
uses data found in the generated Makefile. An undetected
missing piece breaks the process. But it may well be
that your Bundle installs some prerequisite later than
some depending item and thus your second try is able to
resolve everything. Please note, CPAN.pm does not know
the dependency tree in advance and cannot sort the queue
of things to install in a topologically correct order.
It resolves perfectly well IFF all modules declare the
prerequisites correctly with the PREREQ_PM attribute to
MakeMaker. For bundles which fail and you need to
install often, it is recommended sort the Bundle defini-
tion file manually. It is planned to improve the meta-
data situation for dependencies on CPAN in general, but
this will still take some time.
8) In our intranet we have many modules for internal use.
How can I integrate these modules with CPAN.pm but
without uploading the modules to CPAN?
Have a look at the CPAN::Site module.
9) When I run CPAN's shell, I get error msg about line 1 to
4, setting meta input/output via the /etc/inputrc file.
Some versions of readline are picky about capitalization
in the /etc/inputrc file and specifically RedHat 6.2
comes with a /etc/inputrc that contains the word "on" in
lowercase. Change the occurrences of "on" to "On" and
the bug should disappear.
10) Some authors have strange characters in their names.
Internally CPAN.pm uses the UTF-8 charset. If your ter-
minal is expecting ISO-8859-1 charset, a converter can
be activated by setting term_is_latin to a true value in
your config file. One way of doing so would be
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cpan> ! $CPAN::Config->{term_is_latin}=1
Extended support for converters will be made available
as soon as perl becomes stable with regard to charset
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 man-
page at
http://member.nifty.ne.jp/hippo2000/perltips/CPAN.htm
SEE ALSOperl(1), CPAN::Nox(3)perl v5.8.8 2005-02-05 22
