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Installation of mod_perl-enabled Apache Without Superuser Privileges Page 2

By Stas Bekman (Send Email)
Posted Jul 14, 2000


From now on, any time you want to install perl modules locally you simply execute:

  % perl Makefile.PL 'cat ~/.perl_dirs'
  % make
  % make test
  % make install

Using this method you can easily maintain several Perl module repositories. For example, you could have one for production Perl and another for development:

  % perl Makefile.PL 'cat ~/.perl_dirs.production'

or:

  % perl Makefile.PL 'cat ~/.perl_dirs.develop'

Making Your Scripts Find the Locally Installed Modules

Perl modules are generally placed in four main directories. To find these directories, execute:


  % perl -V

The output contains important information about your Perl installation. At the end you will see:

  Characteristics of this binary (from libperl):
  Built under linux
  Compiled at Apr  6 1999 23:34:07
  @INC:
    /usr/lib/perl5/5.00503/i386-linux
    /usr/lib/perl5/5.00503
    /usr/lib/perl5/site_perl/5.005/i386-linux
    /usr/lib/perl5/site_perl/5.005
    .

It shows us the content of the Perl special variable @INC, which is used by Perl to look for its modules. It is equivalent to the PATH environment variable in Unix shells which is used to find executable programs.

Notice that Perl looks for modules in the . directory, too, which stands for the current directory. It's the last entry in the above output.

Of course this example is from version 5.00503 of Perl installed on my x86 architecture PC running Linux. That's why you see i386-linux and 5.00503. If your system runs a different version of Perl, operating system, processor or chipset architecture, then some of the directories will have different names.

I also have a perl-5.6.0 installed under /usr/local/lib/ so when I do:

  % /usr/local/bin/perl5.6.0 -V

I see:

  @INC:
    /usr/local/lib/perl5/5.6.0/i586-linux
    /usr/local/lib/perl5/5.6.0
    /usr/local/lib/site_perl/5.6.0/i586-linux
    /usr/local/lib/site_perl

Note that it's still Linux, but the newer Perl version uses the version of my Pentium processor (thus the i586 and not i386). This makes use of compiler optimizations for Pentium processors when the binary Perl extensions are created.

All the platform specific files, such as compiled C files glued to Perl with XS or SWIG, are supposed to go into the i386-linux-like directories.

Important: As we have installed the Perl modules into non-standard directories, we have to let Perl know where to look for the four directories. There are two ways to accomplish this. You can either set the PERL5LIB environment variable, or you can modify the @INC variable in your scripts.

Assuming that we use perl-5.00503, in our example the directories are:


    /home/sbekman/lib/perl5/5.00503/i386-linux
    /home/sbekman/lib/perl5/5.00503
    /home/sbekman/lib/perl5/site_perl/5.005/i386-linux
    /home/sbekman/lib/perl5/site_perl/5.005

As mentioned before, you find the exact directories by executing perl -V and replacing the global Perl installation's base directory with your home directory.

Modifying @INC is quite easy. The best approach is to use the lib module (pragma), by adding the following snippet at the top of any of your scripts that require the locally installed modules:

  use lib qw(/home/stas/lib/perl5/5.00503/
             /home/stas/lib/perl5/site_perl/5.005);



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