Installing your own Perl 5 modules


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Installing Your Own Perl 5 Modules

NOTE: The Perl 5 module that you wish to install may be included in our pre-packaged distribution or may be installable using the vcpan utility. Both of these methods are preferable to those detailed below. See the Perl documentation for more details.

Installing Perl 5 modules yourself on your Virtual Server can be a tricky exercise. Utilities for installing additional Perl 5 modules generally assume that the installation is being done in the root area of the file system of the host machine. As a Virtual Server user you do not have access to the root area of the host machine. So, you must install Perl 5 modules within your Virtual Server file system.

Installing Perl 5 modules
Setting the directories
Locally-required modules
Module installation using CPAN.pm

Installing Perl 5 Modules
Normally, the perl 5 module installation procedure includes commands something like these:

% perl 5 Makefile.PL
% make
% make test
% make install
% make clean

The first command, perl 5 Makefile.PL, directs perl 5 to create a makefile for the new module you are installing. When installing a Perl 5 module you must designate on the command line the home directory of your perl 5 installation. That information is used by perl 5 to create the makefile. Substitute the following command for Perl 5 Makefile.PL:

   % perl 5 Makefile.PL PREFIX=/usr/home/<username>/usr/local

The value <username> above should be replaced with the username of your Virtual Server. So the complete installation process is:

   % perl 5 Makefile.PL PREFIX=/usr/home/<username>/usr/local
   % make
   % make test 
   % make install

For older modules it may be necessary to designate several other variables on the command line during the module installation:

   % perl5 Makefile.PL PREFIX=/usr/home//usr/local \
   INSTALLPRIVLIB=/usr/home//usr/local/lib/perl5 \
   INSTALLSCRIPT=/usr/home//usr/local/bin \
   INSTALLSITELIB=/usr/home//usr/local/lib/perl5/site_perl \
   INSTALLBIN=/usr/home//usr/local/bin \
   INSTALLMAN1DIR=/usr/home//usr/local/lib/perl5/man \
   INSTALLMAN3DIR=/usr/home//usr/local/lib/perl5/man/man3

To save yourself some typing you can create a file and put these variable assignments above in the file (<filename>) something like this:

   PREFIX=/usr/home//usr/local \
   INSTALLPRIVLIB=/usr/home//usr/local/lib/perl5 \
   INSTALLSCRIPT=/usr/home//usr/local/bin \
   INSTALLSITELIB=/usr/home//usr/local/lib/perl5/site_perl \
   INSTALLBIN=/usr/home//usr/local/bin \
   INSTALLMAN1DIR=/usr/home//usr/local/lib/perl5/man \
   INSTALLMAN3DIR=/usr/home//usr/local/lib/perl5/man/man3

Then, each time you install a Perl 5 module you can use the following syntax:

% perl 5 Makefile.PL 'cat <filename>'
% make
% make test
% make install
% make clean

You also can have a few different local modules installation procedures, for example one for production perl and another for development:

% perl 5 Makefile.PL 'cat <filename>.production

% perl 5 Makefile.PL 'cat <filename>.development'

Making Scripts Find the Modules you have Installed
When you install Perl 5 on your Virtual Server, all pre-installed modules are installed into these 4 directories (depending on which version of perl 5 you are installing):

/usr/lib/perl5
/usr/lib/perl5/i386-bsdos/5.00X
/usr/lib/perl5/site_perl/i386-bsdos
/usr/lib/perl5/site_perl

These 4 directories are already preset in the perl 5's @INC array. That array contains the paths that Perl 5 searches in order to find modules. If you install Perl 5 modules locally as described above, you will need to append these two directories, which are in your Virtual Server, to the @INC array:

/usr/home/<username>/usr/local/lib/perl5 /usr/home/<username>/usr/local/lib/perl5/site_perl

The architecture-specific directories are being searched by Perl automatically. Each time you want to use modules in that path you should add the following line to your scripts:

 use lib qw(/usr/home/<username>/usr/local/lib/perl5
            /usr/home/<username>/usr/local/lib/perl5/site_perl);

You don't have to put it into a BEGIN block; the lib.pm module takes care of that for you. It also adds the architecture specific directories.

You also can use a BEGIN block to include your installed modules:

BEGIN { unshift @INC, qw(/usr/home/<username>/usr/local/lib/perl5 /usr/home/<username>/usr/local/lib/perl5/site_perl); }

The use lib construct, however, seems to be cleaner and the unshift @INC construct doesn't automatically add the architecture specific directories to the @INC array.

Installing New Modules that Require Locally Installed Modules
Okay, imagine that you have installed module A in /usr/home/<username>/usr/local/lib/perl5. Now you want to install a module B that demands module A to be already installed. You know that you have installed the A module, but amazingly B can't locate it. Why? Because when you try to install the module B it doesn't know that you have module A installed locally. (Locally here means 'within your Virtual Server file system' rather than the root file system of the host machine.) Perl 5 searches the basic 4 directories as defined by default in the @INC array. But your local directories aren't listed there.

The solution is simple. The PERL5LIB environment variable does the same job in the shell as use lib does in your script. So if you use csh/tcsh type the following at the command line:

% setenv PERL5LIB \ /usr/home/<username>/usr/local/lib/perl5:/usr/home/<username>/usr/local/lib/perl5/site_perl

Check the man page of your favorite shell how to set the environment variables if you use a shell different from csh/tcsh. Put this setenv statement into .login or another file that is being sourced each time you login into your account and you will not have to worry to remember setting it each time you login.

Module Installation Using CPAN.pm
An alternative to manually installing perl5 modules is the CPAN.pm module which automates module download and installation. If you have perl5.004 or higher installed you have it bundled with the distribution. If not, you can download it from CPAN.

Once the CPAN.pm module is installed, you can use it to install other modules.

When you initially run the following command:

% perl5 -MCPAN -e shell

it will ask you a few questions. You can use all the defaults, except for this one

  Parameters for the 'perl Makefile.PL' command? [] PREFIX=/usr/home//usr/local

and this one:

   Parameters for the 'make install' command? [] INSTALLMAN3DIR=/usr/home//usr/local/lib/perl5/man/man3

When it asks for your favorite CPAN site, try this:

   Please enter it here: ftp://ftp.cs.colorado.edu/pub/perl/CPAN/

After configuration of the module is complete, you will see a > prompt. Then you can try installing modules. To install the CGI module, do this:

> install CGI

It will fetch the latest CGI module, unpack it, make it, test it and install it into your local area or the directory you specified as the PREFIX directory. The command:

> i /CGI/

will return the list of modules that match that pattern.

The CPAN.pm module has more functionality, like checking for the latest modules, for example. To learn more about the CPAN.pm module, read the manual:

% perldoc CPAN

SEE ALSO:

Installing mod_perl Apache Dynamic Module

Virtual Server Basics

Server Configuration

Server Add-ons

Developer Tools

Database Tools

CGI Scriptorium

Recommended Perl Books

BOOKS TO HELP YOU:

Learning Perl (2nd Edition)
$17.97

Programming Perl
$23.97

Programming the Perl DBI
$24.47

Perl Modules
$31.99

Perl in a Nutshell : A Desktop Quick Reference

Perl in a Nutshell: A Desktop Quick Reference
$19.96