Schema verification with "Kwalify"
If you have the "Kwalify" module installed (which is part of the
Bundle::CPANxxl), then all your distroprefs files are checked for
syntactic correctness.
Example Distroprefs Files
"CPAN.pm" comes with a collection of example YAML files. Note that these
are really just examples and should not be used without care because
they cannot fit everybody's purpose. After all, the authors of the
packages that ask questions had a need to ask, so you should watch their
questions and adjust the examples to your environment and your needs.
You have been warned:-)
PROGRAMMER'S INTERFACE
If you do not enter the shell, shell commands are available both as
methods ("CPAN::Shell->install(...)") and as functions in the calling
package ("install(...)"). Before calling low-level commands, it makes
sense to initialize components of CPAN you need, e.g.:
CPAN::HandleConfig->load;
CPAN::Shell::setup_output;
CPAN::Index->reload;
High-level commands do such initializations automatically.
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. The arguments on the commandline are
passed as arguments to the method.
So if you take for example the shell command
notest install A B C
the actually executed command is
CPAN::Shell->notest("install","A","B","C");
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 returns only 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 for distributions. Note: it does not
expand to CPAN::Author objects.
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# install everything that is outdated on my disk: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 $mod (qw(Net::FTP Digest::SHA Data::Dumper)) {
CPAN::Shell->install($mod);
}
# list all modules on my disk that have no VERSION number
for $mod (CPAN::Shell->expand("Module","/./")) {
next unless $mod->inst_file;
# MakeMaker convention for undefined $VERSION:
next unless $mod->inst_version eq "undef";
print "No VERSION in ", $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 schedule a *cron* job to watch 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 any output should all modules be up to date, 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.
If you prefer to do it more in a programmerish style in one single
process, something like this may better suit you:
# 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 too much output every day, you may want to watch only
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 $mod->uptodate;
# new mod_perl arrived, let me know all update recommendations
CPAN::Shell->r;
Methods in the other Classes
CPAN::Author::as_glimpse()
Returns a one-line description of the author
CPAN::Author::as_string()
Returns a multi-line description of the author
CPAN::Author::email()
Returns the author's email address
CPAN::Author::fullname()
Returns the author's name
CPAN::Author::name()
An alias for fullname
CPAN::Bundle::as_glimpse()
Returns a one-line description of the bundle
CPAN::Bundle::as_string()
Returns a multi-line description of the bundle
CPAN::Bundle::clean()
Recursively runs the "clean" method on all items contained in the
bundle.
CPAN::Bundle::contains()
Returns a list of objects' IDs contained in a bundle. The associated
objects may be bundles, modules or distributions.
CPAN::Bundle::force($method,@args)
Forces CPAN to perform a task that it normally would have refused to
do. 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. See also the section above on
the "force" and the "fforce" pragma.
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 up-to-date.
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::author
Returns the CPAN::Author object of the maintainer who uploaded this
distribution
CPAN::Distribution::pretty_id()
Returns a string of the form "AUTHORID/TARBALL", where AUTHORID is
the author's PAUSE ID and TARBALL is the distribution filename.
CPAN::Distribution::base_id()
Returns the distribution filename without any archive suffix. E.g
"Foo-Bar-0.01"
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.
Works only for distributions listed in the 02packages.details.txt.gz
file. This typically means that just 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 it normally would have refused to
do. 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. See also the section
above on the "force" and the "fforce" pragma.
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" is issued in
any case and if this fails, the install is cancelled. The
cancellation can be avoided by letting "force" run the "install" for
you.
This install method only has the power to install the distribution
if there are no dependencies in the way. To install an object along
with all its dependencies, use CPAN::Shell->install.
Note that install() gives no meaningful return value. See
uptodate().
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 subshell returns.
CPAN::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" or "perl Build.PL" and "make" there.
CPAN::Distribution::perldoc()
Downloads the pod documentation of the file associated with a
distribution (in HTML format) and runs it through the external
command *lynx* specified in "$CPAN::Config->{lynx}". If *lynx* isn't
available, it converts it to plain text with the external command
*html2text* and runs it through the pager specified in
"$CPAN::Config->{pager}".
CPAN::Distribution::prefs()
Returns the hash reference from the first matching YAML file that
the user has deposited in the "prefs_dir/" directory. The first
succeeding match wins. The files in the "prefs_dir/" are processed
alphabetically, and the canonical distro name (e.g.
AUTHOR/Foo-Bar-3.14.tar.gz) is matched against the regular
expressions stored in the $root->{match}{distribution} attribute
value. Additionally all module names contained in a distribution are
matched against the regular expressions in the
$root->{match}{module} attribute value. The two match values are
ANDed together. Each of the two attributes are optional.
CPAN::Distribution::prereq_pm()
Returns the hash reference that has been announced by a distribution
as the "requires" and "build_requires" elements. These can be
declared either by the "META.yml" (if authoritative) or can be
deposited after the run of "Build.PL" in the file "./_build/prereqs"
or after the run of "Makfile.PL" written as the "PREREQ_PM" hash in
a comment in the produced "Makefile". *Note*: this method only works
after an attempt has been made to "make" the distribution. Returns
undef otherwise.
CPAN::Distribution::readme()
Downloads the README file associated with a distribution and runs it
through the pager specified in "$CPAN::Config->{pager}".
CPAN::Distribution::reports()
Downloads report data for this distribution from www.cpantesters.org
and displays a subset of them.
CPAN::Distribution::read_yaml()
Returns the content of the META.yml of this distro as a hashref.
Note: works only after an attempt has been made to "make" the
distribution. Returns undef otherwise. Also returns undef if the
content of META.yml is not authoritative. (The rules about what
exactly makes the content authoritative are still in flux.)
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
up-to-date. Relies on containsmods.
CPAN::Index::force_reload()
Forces a reload of all indices.
CPAN::Index::reload()
Reloads all indices if they have not been read for more than
"$CPAN::Config->{index_expire}" days.
CPAN::InfoObj::dump()
CPAN::Author, CPAN::Bundle, CPAN::Module, and CPAN::Distribution
inherit this method. It prints the data structure associated with an
object. Useful for debugging. Note: the data structure is considered
internal and thus subject to change without notice.
CPAN::Module::as_glimpse()
Returns a one-line description of the module in four columns: The
first column contains the word "Module", the second column consists
of one character: an equals sign if this module is already installed
and up-to-date, a less-than sign if this module is installed but can
be upgraded, and a space if the module is not installed. The third
column is the name of the module and the fourth column gives
maintainer or distribution information.
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)
CPAN::Module::distribution()
Returns the CPAN::Distribution object that contains the current
version of this module.
CPAN::Module::dslip_status()
Returns a hash reference. The keys of the hash are the letters "D",
"S", "L", "I", and , for development status, support level,
language, interface and public licence respectively. The data for
the DSLIP status are collected by pause.perl.org when authors
register their namespaces. The values of the 5 hash elements are
one-character words whose meaning is described in the table below.
There are also 5 hash elements "DV", "SV", "LV", "IV", and that
carry a more verbose value of the 5 status variables.
Where the 'DSLIP' characters have the following meanings:
D - Development Stage (Note: *NO IMPLIED TIMESCALES*):
i - Idea, listed to gain consensus or as a placeholder
c - under construction but pre-alpha (not yet released)
a/b - Alpha/Beta testing
R - Released
M - Mature (no rigorous definition)
S - Standard, supplied with Perl 5
S - Support Level:
m - Mailing-list
d - Developer
u - Usenet newsgroup comp.lang.perl.modules
n - None known, try comp.lang.perl.modules
a - abandoned; volunteers welcome to take over maintenance
L - Language Used:
p - Perl-only, no compiler needed, should be platform independent
c - C and perl, a C compiler will be needed
h - Hybrid, written in perl with optional C code, no compiler needed
+ - C++ and perl, a C++ compiler will be needed
o - perl and another language other than C or C++
I - Interface Style
f - plain Functions, no references used
h - hybrid, object and function interfaces available
n - no interface at all (huh?)
r - some use of unblessed References or ties
O - Object oriented using blessed references and/or inheritance
P - Public License
p - Standard-Perl: user may choose between GPL and Artistic
g - GPL: GNU General Public License
l - LGPL: "GNU Lesser General Public License" (previously known as
"GNU Library General Public License")
b - BSD: The BSD License
a - Artistic license alone
2 - Artistic license 2.0 or later
o - open source: approved by www.opensource.org
d - allows distribution without restrictions
r - restricted distribution
n - no license at all
CPAN::Module::force($method,@args)
Forces CPAN to perform a task it would normally refuse to do. Force
takes as arguments a method name to be invoked and any number of
additional arguments to pass that method. The internals of the
object get the needed changes so that CPAN.pm does not refuse to
take the action. See also the section above on the "force" and the
"fforce" pragma.
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 as perl itself stops searching @INC once it
finds a module.
CPAN::Module::available_file()
Returns the filename of the module found in PERL5LIB or @INC. The
first file found is reported. The advantage of this method over
"inst_file" is that modules that have been tested but not yet
installed are included because PERL5LIB keeps track of tested
modules.
CPAN::Module::inst_version()
Returns the version number of the installed module in readable
format.
CPAN::Module::available_version()
Returns the version number of the available 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
downloaded within this session, does the equivalent on the
downloaded module even if it hasn't been installed yet.
CPAN::Module::perldoc()
Runs a "perldoc" on this module.
CPAN::Module::readme()
Runs a "readme" on the distribution associated with this module.
CPAN::Module::reports()
Calls the reports() method on the associated distribution object.
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 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, i.e. *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
The CPAN program is trying to depend on as little as possible so the
user can use it in hostile environment. It works better the more goodies
the environment provides. For example if you try in the CPAN shell
install Bundle::CPAN
or
install Bundle::CPANxxl
you will find the shell more convenient than the bare shell before.
If you have a local mirror of CPAN and can access all files with "file:"
URLs, then you only need a perl later 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.
UTILITIES
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 $VERSION can be
parsed, please try the above method.
* come as compressed or gzipped tarfiles or as zip files and contain a
"Makefile.PL" or "Build.PL" (well, we try to handle a bit more, but
with little enthusiasm).
Debugging
Debugging this module is more than a bit complex due to interference
from the software producing the indices on CPAN, the mirroring process
on CPAN, packaging, configuration, synchronicity, and even (gasp!) due
to bugs within the CPAN.pm module itself.
For debugging the code of CPAN.pm itself in interactive mode, some
debugging aid can be turned on for most packages within CPAN.pm with one
of
o debug package...
sets debug mode for packages.
o debug -package...
unsets debug mode for packages.
o debug all
turns debugging on for all packages.
o debug number
which sets the debugging packages directly. Note that "o debug 0" turns
debugging off.
What seems a successful strategy is the combination of "reload cpan" and
the debugging switches. Add a new debug statement while running in the
shell and then issue a "reload cpan" and see the new debugging messages
immediately without losing the current context.
"o debug" without an argument lists the valid package names and the
current set of packages in debugging mode. "o debug" has built-in
completion support.
For debugging of CPAN data there is the "dump" command which takes the
same arguments as make/test/install and outputs each object's
Data::Dumper dump. If an argument looks like a perl variable and
contains one of "$", "@" or "%", it is eval()ed and fed to Data::Dumper
directly.
Floppy, Zip, Offline Mode
CPAN.pm works nicely without network access, too. If you maintain
machines that are not networked at all, you should consider working with
"file:" URLs. You'll 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
$CPAN::Config->{build_dir}) directory on a floppy. This floppy is kind
of a personal CPAN. CPAN.pm on the non-networked machines works nicely
with this floppy. See also below the paragraph about CD-ROM support.
Basic Utilities for Programmers
has_inst($module)
Returns true if the module is installed. Used to load all modules into
the running CPAN.pm that are considered optional. The config variable
"dontload_list" intercepts the "has_inst()" call such that an optional
module is not loaded despite being available. For example, the
following command will prevent "YAML.pm" from being loaded:
cpan> o conf dontload_list push YAML
See the source for details.
use_inst($module)
Similary to has_inst() tries to load optional library but also dies if
library is not available
has_usable($module)
Returns true if the module is installed and in a usable state. Only
useful for a handful of modules that are used internally. See the
source for details.
instance($module)
The constructor for all the singletons used to represent modules,
distributions, authors, and bundles. If the object already exists,
this method returns the object; otherwise, it calls the constructor.
frontend()
frontend($new_frontend)
Getter/setter for frontend object. Method just allows to subclass
CPAN.pm.
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.
But we try to make it easy to add security on demand:
Cryptographically signed modules
Since release 1.77, CPAN.pm has been able to verify cryptographically
signed module distributions using Module::Signature. The CPAN modules
can be signed by their authors, thus giving more security. The simple
unsigned MD5 checksums that were used before by CPAN protect mainly
against accidental file corruption.
You will need to have Module::Signature installed, which in turn
requires that you have at least one of Crypt::OpenPGP module or the
command-line gpg tool installed.
You will also need to be able to connect over the Internet to the public
key servers, like pgp.mit.edu, and their port 11731 (the HKP protocol).
The configuration parameter check_sigs is there to turn signature
checking on or off.
EXPORT
Most functions in package CPAN are exported by default. The reason for
this is that the primary use is intended for the cpan shell or for
one-liners.
ENVIRONMENT
When the CPAN shell enters a subshell via the look command, it sets the
environment CPAN_SHELL_LEVEL to 1, or increments that variable if it is
already set.
When CPAN runs, it sets the environment variable PERL5_CPAN_IS_RUNNING
to the ID of the running process. It also sets PERL5_CPANPLUS_IS_RUNNING
to prevent runaway processes which could happen with older versions of
Module::Install.
When running "perl Makefile.PL", the environment variable
"PERL5_CPAN_IS_EXECUTING" is set to the full path of the "Makefile.PL"
that is being executed. This prevents runaway processes with newer
versions of Module::Install.
When the config variable ftp_passive is set, all downloads will be run
with the environment variable FTP_PASSIVE set to this value. This is in
general a good idea as it influences both Net::FTP and LWP based
connections. The same effect can be achieved by starting the cpan shell
with this environment variable set. For Net::FTP alone, one can also
always set passive mode by running libnetcfg.
POPULATE AN INSTALLATION WITH LOTS OF MODULES
Populating a freshly installed perl with one's 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 installed for the current perl
interpreter. It's recommended to run this command once only, 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 go out for coffee (possibly even in a
different city).
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 annoying that so many
distributions need some interactive configuring. So what you can try to
accomplish in your private bundle file is to have the packages that need
to be configured early in the file and the gentle ones later, so you can
go out for coffee after a few minutes and leave CPAN.pm to churn away
unattended.
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 information 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 likely that you
can configure *ncftp* so that it works through your firewall.
Three basic types of firewalls
Firewalls can be categorized into three basic types.
http firewall
This is when the firewall machine runs a web server, and to access
the outside world, you must do so via that web server. If you set
environment variables like http_proxy or ftp_proxy to values
beginning with http://, or in your web browser you've proxy
information set, then you know you are running behind an http
firewall.
To access servers outside these types of firewalls with perl (even
for ftp), you need LWP or HTTP::Tiny.
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
need Net::FTP.
One-way visibility
One-way visibility means these firewalls try to make themselves
invisible to users inside the firewall. An FTP data connection is
normally created by sending your IP address to the remote server and
then listening for the return connection. But the remote server will
not be able to connect to you because of the firewall. 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 were
not there.
IP Masquerade
This is when the firewall implemented in the kernel (via NAT, or
networking address translation), 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 usually need
to set the environment variable "FTP_PASSIVE" or the config
variable ftp_passive to a true value.
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
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?
As of CPAN 1.9463, if you do not have permission to write the
default perl library directories, CPAN's configuration process will
ask you whether you want to bootstrap , which makes
keeping a personal perl library directory easy.
Another thing you should bear in mind is that the UNINST parameter
can be dangerous when you are installing into a private area because
you might accidentally remove modules that other people depend on
that are not using the private area.
6) How to get a package, unwrap it, and make a change before building
it?
Have a look at the "look" (!) command.
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 META.yml file or 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 if all
modules declare the prerequisites correctly with the PREREQ_PM
attribute to MakeMaker or the "requires" stanza of Module::Build.
For bundles which fail and you need to install often, it is
recommended to sort the Bundle definition file manually.
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 an error message about things in my
"/etc/inputrc" (or "~/.inputrc") file.
These are readline issues and can only be fixed by studying readline
configuration on your architecture and adjusting the referenced file
accordingly. Please make a backup of the "/etc/inputrc" or
"~/.inputrc" and edit them. Quite often harmless changes like
uppercasing or lowercasing some arguments solves the problem.
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> o conf term_is_latin 1
If other charset support is needed, please file a bug report against
CPAN.pm at rt.cpan.org and describe your needs. Maybe we can extend
the support or maybe UTF-8 terminals become widely available.
Note: this config variable is deprecated and will be removed in a
future version of CPAN.pm. It will be replaced with the conventions
around the family of $LANG and $LC_* environment variables.
11) When an install fails for some reason and then I correct the error
condition and retry, CPAN.pm refuses to install the module, saying
"Already tried without success".
Use the force pragma like so
force install Foo::Bar
Or you can use
look Foo::Bar
and then "make install" directly in the subshell.
12) How do I install a "DEVELOPER RELEASE" of a module?
By default, CPAN will install the latest non-developer release of a
module. If you want to install a dev release, you have to specify
the partial path starting with the author id to the tarball you wish
to install, like so:
cpan> install KWILLIAMS/Module-Build-0.27_07.tar.gz
Note that you can use the "ls" command to get this path listed.
13) How do I install a module and all its dependencies from the
commandline, without being prompted for anything, despite my CPAN
configuration (or lack thereof)?
CPAN uses ExtUtils::MakeMaker's prompt() function to ask its
questions, so if you set the PERL_MM_USE_DEFAULT environment
variable, you shouldn't be asked any questions at all (assuming the
modules you are installing are nice about obeying that variable as
well):
% PERL_MM_USE_DEFAULT=1 perl -MCPAN -e 'install My::Module'
14) How do I create a Module::Build based Build.PL derived from an
ExtUtils::MakeMaker focused Makefile.PL?
http://search.cpan.org/dist/Module-Build-Convert/
15) I'm frequently irritated with the CPAN shell's inability to help me
select a good mirror.
CPAN can now help you select a "good" mirror, based on which ones
have the lowest 'ping' round-trip times. From the shell, use the
command 'o conf init urllist' and allow CPAN to automatically select
mirrors for you.
Beyond that help, the urllist config parameter is yours. You can add
and remove sites at will. You should find out which sites have the
best up-to-dateness, bandwidth, reliability, etc. and are
topologically close to you. Some people prefer fast downloads,
others up-to-dateness, others reliability. You decide which to try
in which order.
Henk P. Penning maintains a site that collects data about CPAN
sites:
http://mirrors.cpan.org/
Also, feel free to play with experimental features. Run
o conf init randomize_urllist ftpstats_period ftpstats_size
and choose your favorite parameters. After a few downloads running
the "hosts" command will probably assist you in choosing the best
mirror sites.
16) Why do I get asked the same questions every time I start the shell?
You can make your configuration changes permanent by calling the
command "o conf commit". Alternatively set the "auto_commit"
variable to true by running "o conf init auto_commit" and answering
the following question with yes.
17) Older versions of CPAN.pm had the original root directory of all
tarballs in the build directory. Now there are always random
characters appended to these directory names. Why was this done?
The random characters are provided by File::Temp and ensure that
each module's individual build directory is unique. This makes
running CPAN.pm in concurrent processes simultaneously safe.
18) Speaking of the build directory. Do I have to clean it up myself?
You have the choice to set the config variable "scan_cache" to
"never". Then you must clean it up yourself. The other possible
values, "atstart" and "atexit" clean up the build directory when you
start (or more precisely, after the first extraction into the build
directory) or exit the CPAN shell, respectively. If you never start
up the CPAN shell, you probably also have to clean up the build
directory yourself.
19) How can I switch to sudo instead of local::lib?
The following 5 environment veriables need to be reset to the
previous values: PATH, PERL5LIB, PERL_LOCAL_LIB_ROOT, PERL_MB_OPT,
PERL_MM_OPT; and these two CPAN.pm config variables must be
reconfigured: make_install_make_command and
mbuild_install_build_command. The five env variables have probably
been overwritten in your $HOME/.bashrc or some equivalent. You
either find them there and delete their traces and logout/login or
you override them temporarily, depending on your exact desire. The
two cpanpm config variables can be set with:
o conf init /install_.*_command/
probably followed by
o conf commit
COMPATIBILITY
OLD PERL VERSIONS
CPAN.pm is regularly tested to run under 5.005 and assorted newer
versions. It is getting more and more difficult to get the minimal
prerequisites working on older perls. It is close to impossible to get
the whole Bundle::CPAN working there. If you're in the position to have
only these old versions, be advised that CPAN is designed to work fine
without the Bundle::CPAN installed.
To get things going, note that GBARR/Scalar-List-Utils-1.18.tar.gz is
compatible with ancient perls and that File::Temp is listed as a
prerequisite but CPAN has reasonable workarounds if it is missing.
CPANPLUS
This module and its competitor, the CPANPLUS module, are both much
cooler than the other. CPAN.pm is older. CPANPLUS was designed to be
more modular, but it was never intended to be compatible with CPAN.pm.
CPANMINUS
In the year 2010 App::cpanminus was launched as a new approach to a cpan
shell with a considerably smaller footprint. Very cool stuff.
SECURITY ADVICE
This software enables you to upgrade software on your computer and so is
inherently dangerous because the newly installed software may contain
bugs and may alter the way your computer works or even make it unusable.
Please consider backing up your data before every upgrade.
BUGS
Please report bugs via
Before submitting a bug, please make sure that the traditional method of
building a Perl module package from a shell by following the
installation instructions of that package still works in your
environment.
AUTHOR
Andreas Koenig ""
LICENSE
This program is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.
See
TRANSLATIONS
Kawai,Takanori provides a Japanese translation of a very old version of
this manpage at
SEE ALSO
Many people enter the CPAN shell by running the cpan utility program
which is installed in the same directory as perl itself. So if you have
this directory in your PATH variable (or some equivalent in your
operating system) then typing "cpan" in a console window will work for
you as well. Above that the utility provides several commandline
shortcuts.
melezhik (Alexey) sent me a link where he published a chef recipe to
work with CPAN.pm: http://community.opscode.com/cookbooks/cpan.