How to Install a CPAN Perl Module

Trivial for those who know, but there's a first time for everything.

[EDIT: See Installing CPAN Perl Modules Revisited for a newer take.]

Here's how to install a module from CPAN:

perl -MCPAN -e 'install full::module::name'

The first time you run this, it will answer with

CPAN is the world-wide archive of perl resources. It consists of about
100 sites that all replicate the same contents all around the globe.
Many countries have at least one CPAN site already. The resources
found on CPAN are easily accessible with the CPAN.pm module. If you
want to use CPAN.pm, you have to configure it properly.

If you do not want to enter a dialog now, you can answer 'no' to this
question and I'll try to autoconfigure. (Note: you can revisit this
dialog anytime later by typing 'o conf init' at the cpan prompt.)

Are you ready for manual configuration? [yes]

You can say yes and continue hitting the Enter key to answer all questions by default, or you can say no save the trouble. I always like seeing what choices are made for me, so here it goes:

The following questions are intended to help you with the
configuration. The CPAN module needs a directory of its own to cache
important index files and maybe keep a temporary mirror of CPAN files.
This may be a site-wide directory or a personal directory.

First of all, I'd like to create this directory. Where?

CPAN build and cache directory? [/root/.cpan]


If you want, I can keep the source files after a build in the cpan
home directory. If you choose so then future builds will take the
files from there. If you don't want to keep them, answer 0 to the
next question.

How big should the disk cache be for keeping the build directories
with all the intermediate files?

Cache size for build directory (in MB)? [10]


By default, each time the CPAN module is started, cache scanning
is performed to keep the cache size in sync. To prevent from this,
disable the cache scanning with 'never'.

Perform cache scanning (atstart or never)? [atstart]


To considerably speed up the initial CPAN shell startup, it is
possible to use Storable to create a cache of metadata. If Storable
is not available, the normal index mechanism will be used.

Cache metadata (yes/no)? [yes]


The next option deals with the charset your terminal supports. In
general CPAN is English speaking territory, thus the charset does not
matter much, but some of the aliens out there who upload their
software to CPAN bear names that are outside the ASCII range. If your
terminal supports UTF-8, you say no to the next question, if it
supports ISO-8859-1 (also known as LATIN1) then you say yes, and if it
supports neither nor, your answer does not matter, you will not be
able to read the names of some authors anyway. If you answer no, names
will be output in UTF-8.

Your terminal expects ISO-8859-1 (yes/no)? [yes] no


If you have one of the readline packages (Term::ReadLine::Perl,
Term::ReadLine::Gnu, possibly others) installed, the interactive CPAN
shell will have history support. The next two questions deal with the
filename of the history file and with its size. If you do not want to
set this variable, please hit SPACE RETURN to the following question.

File to save your history? [/root/.cpan/histfile]
Number of lines to save? [100]


The CPAN module can detect when a module that which you are trying to
build depends on prerequisites. If this happens, it can build the
prerequisites for you automatically ('follow'), ask you for
confirmation ('ask'), or just ignore them ('ignore'). Please set your
policy to one of the three values.

Policy on building prerequisites (follow, ask or ignore)? [ask]


The CPAN module will need a few external programs to work properly.
Please correct me, if I guess the wrong path for a program. Don't
panic if you do not have some of them, just press ENTER for those. To
disable the use of a download program, you can type a space followed
by ENTER.

Where is your gzip program? [/bin/gzip]
Where is your tar program? [/bin/tar]
Where is your unzip program? [/usr/bin/unzip]
Where is your make program? [/usr/bin/make]
Where is your lynx program? [/usr/bin/lynx]
Where is your wget program? [/usr/bin/wget]
Warning: ncftpget not found in PATH
Where is your ncftpget program? []
Warning: ncftp not found in PATH
Where is your ncftp program? []
Where is your ftp program? [/usr/bin/ftp]
Where is your gpg program? [/usr/bin/gpg]
What is your favorite pager program? [less]
What is your favorite shell? [/bin/bash]


Every Makefile.PL is run by perl in a separate process. Likewise we
run 'make' and 'make install' in processes. If you have any
parameters (e.g. PREFIX, LIB, UNINST or the like) you want to pass
to the calls, please specify them here.

If you don't understand this question, just press ENTER.

Parameters for the 'perl Makefile.PL' command?
Typical frequently used settings:

    PREFIX=~/perl       non-root users (please see manual for more hints)

Your choice:  []
Parameters for the 'make' command?
Typical frequently used setting:

    -j3              dual processor system

Your choice:  []
Parameters for the 'make install' command?
Typical frequently used setting:

    UNINST=1         to always uninstall potentially conflicting files

Your choice:  []


Sometimes you may wish to leave the processes run by CPAN alone
without caring about them. As sometimes the Makefile.PL contains
question you're expected to answer, you can set a timer that will
kill a 'perl Makefile.PL' process after the specified time in seconds.

If you set this value to 0, these processes will wait forever. This is
the default and recommended setting.

Timeout for inactivity during Makefile.PL? [0]


If you're accessing the net via proxies, you can specify them in the
CPAN configuration or via environment variables. The variable in
the $CPAN::Config takes precedence.

Your ftp_proxy?
Your http_proxy?
Your no_proxy?
You have no /root/.cpan/sources/MIRRORED.BY
  I'm trying to fetch one
CPAN: LWP::UserAgent loaded ok
Fetching with LWP:
  ftp://ftp.perl.org/pub/CPAN/MIRRORED.BY


Now we need to know where your favorite CPAN sites are located. Push
a few sites onto the array (just in case the first on the array won't
work). If you are mirroring CPAN to your local workstation, specify a
file: URL.

First, pick a nearby continent and country (you can pick several of
each, separated by spaces, or none if you just want to keep your
existing selections). Then, you will be presented with a list of URLs
of CPAN mirrors in the countries you selected, along with previously
selected URLs. Select some of those URLs, or just keep the old list.
Finally, you will be prompted for any extra URLs -- file:, ftp:, or
http: -- that host a CPAN mirror.

(1) Africa
(2) Asia
(3) Central America
(4) Europe
(5) North America
(6) Oceania
(7) South America
Select your continent (or several nearby continents) [] 

Continue from here to pick you continent, country, and a list of download hosts and Perl will save your settings:

commit: wrote /usr/lib/perl5/5.8.7/CPAN/Config.pm

At this point it told me the following (and this comes back for every subsequent session):

  There's a new CPAN.pm version (v....) available!
  [Current version is v....]
  You might want to try
    install Bundle::CPAN
    reload cpan
  without quitting the current session. It should be a seamless upgrade
  while we are running...

The message was a bit confusing, because I didn't have a "current session", but this will start one:

perl -MCPAN -e shell;

install Bundle::CPAN did run fine as promised, but it installed/updated a large number of modules and ran for about 10 minutes. However, when I started it the next time, it came up with the following message:

Sorry, we have to rerun the configuration dialog for CPAN.pm due to
the following indispensable but missing parameters:

auto_commit, mbuild_arg, mbuild_install_arg, mbuild_install_build_command, mbuildpl_arg


Normally CPAN.pm keeps config variables in memory and changes need to
be saved in a separate 'o conf commit' command to make them permanent
between sessions. If you set the 'auto_commit' option to true, changes
to a config variable are always automatically committed to disk.

Always commit changes to config variables to disk? [no]


The next questions deal with Module::Build support.

A Build.PL is run by perl in a separate process. Likewise we run
'./Build' and './Build install' in separate processes. If you have any
parameters you want to pass to the calls, please specify them here.

Parameters for the 'perl Build.PL' command?
Typical frequently used settings:

    --install_base /home/xxx             # different installation directory

Your choice:  []

Parameters for the './Build' command?
Setting might be:

    --extra_linker_flags -L/usr/foo/lib  # non-standard library location

Your choice:  []

Do you want to use a different command for './Build install'?
Sudo users will probably prefer:

    su root -c ./Build
or
    sudo ./Build
or
    /path1/to/sudo -u admin_account ./Build

or some such. Your choice:  [./Build]

Parameters for the './Build install' command?
Typical frequently used setting:

    --uninst 1                           # uninstall conflicting files

Your choice:  []

Please remember to call 'o conf commit' to make the config permanent!


cpan shell -- CPAN exploration and modules installation (v1.90)
ReadLine support enabled

cpan[1]> o conf commit
commit: wrote '/usr/lib/perl5/5.8.7/CPAN/Config.pm'

For more information see the CPAN FAQ.