From: Mathieu Blondel <mblondel@...>
Date: 2007-10-31T06:22:48+09:00
Subject: Re: clarification of ruby libraries installation paths?

Austin Ziegler wrote:
> There are no third-party libraries installed in /usr/lib/ruby/1.8.
> Those are in /usr/lib/ruby/site_ruby/1.8 for anyone using setup.rb.
> That's been this way as far as I can remember (and I've been using
> Ruby since 1.6).
>   
Here's my understanding of the problem.

When you run "ruby setup.rb --help", you get:
[...]
  --prefix=path            path prefix of target environment 
[$default_prefix]
[...]
  --siteruby=path          the directory for version-independent aux 
ruby libraries [$default_siteruby]
  --siterubyver=path       the directory for aux ruby libraries 
[$default_siteruby/$version]
[...]

$default_prefix comes from  Config::CONFIG['prefix'] (--prefix option of 
Ruby's configure)
$default_siteruby comes from Config::CONFIG['sitedir'] (--with-sitedir 
option of Ruby's configure)

Distros probably configure Ruby with --prefix=/usr. The default value of 
--with-sitedir in Ruby's configure is PREFIX/lib/ruby/site_ruby. With 
--with-sitedir left as is, a third-party lib installed manually would 
thus end up in /usr/lib/ruby/site_ruby. This is clearly unwanted. 
Therefore, distros configure Ruby with 
--with-sitedir='/usr/local/lib/site_ruby'.

Since, /usr/local/lib/site_ruby is  the default value of 
Config::CONFIG['sitedir'] in distros, all packages for third-party libs 
must be built with --siteruby explicitly specified:

* --siteruby=/usr/lib/ruby/1.8/ for Debian (mixing up with the stdlib)
* --siteruby=/usr/lib/ruby/site_ruby/1.8/ for Fedora
* --siteruby=/usr/lib/ruby/vendor_ruby/1.8/ for openSUSE

The original poster is only asking for an "official statement" from 
Ruby-core developers (if not Matz): "distros, use this directory as the 
standard directory for packaged third-party libs". This is simply for 
the sake of consistency among Linux distributions.

Mathieu Blondel