Building and Installing a CPAN Module (Perl Cookbook, 2nd Edition)

12.21.3. Discussion

Like most programs on the Net, Perl modules are available in source kits stored as tar archives in GNU zip format.[23] If tar warns of "Directory checksum errors", then you downloaded the binary file in text format, mutilating it.

[23]This is not the same as the zip format common on Windows machines, but newer version of Windows winzip will read it. Prior to Perl 5.005, you'll need the standard port of Perl for Win32, not the ActiveState port, to build CPAN modules. Free versions of tar and gnutar are also available for Microsoft systems.

You'll probably have to become a privileged user with adequate permissions to install the module in the system directories. Standard modules are installed in a directory like /usr/lib/perl5, whereas third-party modules are installed in /usr/lib/perl5/site_ perl.

Here's a sample run, showing the installation of the MD5 module:

% gunzip MD5-1.7.tar.gz
% tar xf MD5-1.7.tar
% cd MD5-1.7
% perl Makefile.PL 
Checking if your kit is complete...
Looks good
Writing Makefile for MD5
% make
mkdir ./blib
mkdir ./blib/lib
cp MD5.pm ./blib/lib/MD5.pm
AutoSplitting MD5 (./blib/lib/auto/MD5)
/usr/bin/perl -I/usr/local/lib/perl5/i386 ...
...
cp MD5.bs ./blib/arch/auto/MD5/MD5.bs
chmod 644 ./blib/arch/auto/MD5/MD5.bsmkdir ./blib/man3
Manifying ./blib/man3/MD5.3
% make test
PERL_DL_NONLAZY=1 /usr/bin/perl -I./blib/arch -I./blib/lib
-I/usr/local/lib/perl5/i386-freebsd/5.00404 -I/usr/local/lib/perl5 test.pl
1..14
ok 1
ok 2
...
ok 13
ok 14
% sudo make install
Password:
Installing /usr/local/lib/perl5/site_perl/i386-freebsd/./auto/MD5/
    MD5.so
Installing /usr/local/lib/perl5/site_perl/i386-freebsd/./auto/MD5/
    MD5.bs
Installing /usr/local/lib/perl5/site_perl/./auto/MD5/autosplit.ix
Installing /usr/local/lib/perl5/site_perl/./MD5.pm
Installing /usr/local/lib/perl5/man/man3/./MD5.3
Writing /usr/local/lib/perl5/site_perl/i386-freebsd/auto/MD5/.packlist
Appending installation info to /usr/local/lib/perl5/i386-freebsd/
5.00404/perllocal.pod

If your system manager isn't around or can't be prevailed upon to run the installation, don't worry. When you use Perl to generate the Makefile from template Makefile.PL, you can specify alternate installation directories.

# if you just want the modules installed in your own directory
% perl Makefile.PL LIB=~/lib

# if you have your own complete distribution
% perl Makefile.PL PREFIX=~/perl5-private

An even simpler approach is to use the CPAN module from the command line, because it can search for, download, and install the module you need. Suppose you wanted to find the CPAN module Getopt::Declare. All you'd have to do is type:

% perl -MCPAN -e "install Getopt::Declare"

The first time you use the CPAN module, it will ask you some configuration questions. It saves these away so that when you use it in the future, it won't need to ask you those questions again.

The CPAN module also supports an interactive command shell. This can be used to search for modules whose precise names you're uncertain of, check which CPAN modules have newer versions than you have installed, install bundles of related modules, and various other useful commands.

Here's an example run of the interactive shell.

% perl -MCPAN -e shell

cpan shell -- CPAN exploration and modules installation (v1.70)
ReadLine support enabled

cpan> h

Display Information
 command  argument          description
 a,b,d,m  WORD or /REGEXP/  about authors, bundles, distributions, modules
 i        WORD or /REGEXP/  about anything of above
 r        NONE              reinstall recommendations
 ls       AUTHOR            about files in the author's directory

Download, Test, Make, Install...
 get                        download
 make                       make (implies get)
 test      MODULES,         make test (implies make)
 install   DISTS, BUNDLES   make install (implies test)
 clean                      make clean
 look                       open subshell in these dists' directories
 readme                     display these dists' README files

Other
 h,?           display this menu       ! perl-code   eval a perl command
 o conf [opt]  set and query options   q             quit the cpan shell
 reload cpan   load CPAN.pm again      reload index  load newer indices
 autobundle    Snapshot                force cmd     unconditionally do cmd

cpan> i /inflect/
CPAN: Storable loaded ok
Going to read /home/tchrist/.cpan/Metadata
  Database was generated on Mon, 07 Apr 2003 22:42:33 GMT
Distribution    D/DC/DCONWAY/Lingua-EN-Inflect-1.88.tar.gz
Module          Lingua::EN::Inflect (D/DC/DCONWAY/Lingua-EN-Inflect-1.88.tar.gz)
2 items found

cpan> install Lingua::EN::Inflect
[build and install output deleted]

cpan> quit

The CPAN module is slowly being phased out in favor of CPANPLUS, a module with similar functionality that is built for flexibility as well as power. The CPANPLUS text interface is similar to that of the CPAN module, but it also offers a GUI and programmer interfaces, which can access a lot of functionality that the CPAN module hides.

12.21. Building and Installing a CPAN Module

12.21.1. Problem

12.21.2. Solution

12.21.3. Discussion

12.21.4. See Also