I was testing this out and got the following output when installing a gem:

WARNING: Installing to ~/.gem since /usr/lib/ruby/gems/1.8 and
/usr/bin aren't both writable.
WARNING: You don't have /home/allan/.gem/ruby/1.8/bin in your PATH,
gem executables will not run.

Where are yours installed and is it in your path?

mine is installed to system place but anyway, i found that RUBYOPT was not setup. export RUBYOPT=rubygems made it work like a charm. maybe installation of rubygems package should add it to environment variables automatically?

Adding rubygems maintainer to assignees.

PLease, see that and tell me if is really necessary add the env variable: http://rubygems.org/read/chapter/3#page70

on gentoo (which is my main working platform) installation of rubygems would install gem loading helper as /usr/lib/ruby/site_ruby/auto_gem.rb, and add corresponding environment settings:

contents of auto_gem.rb:
------------------------
# This file is installed by Gentoo's rubygems package.
# It's intended to help automate the loading of rubygems

begin
require 'rubygems'
rescue LoadError
end
---- end ----

$ env | grep RUBY
RUBYOPT=-rauto_gem

that is really useful as you don't have to require rubygems explicitly to every ruby script. i expected to have a similar behaviour on arch linux as well =)

@Kessia: Fixing this "bug" just requires adding a file /etc/profile.d/rubgems.sh (755 permissions) with the "export RUBYOPT=rubygems" line in it to the rubygems package. This is really up to you whether you do this or not, but I don't see the downside in it.

I'll wait some decision for Ruby version 1.9, because it came with rubygems. In next version, i hope this will be in profile.

Ruby 1.9.1 is out and stable... any reason we can't update and fix this issue?

I have put ruby-1.9.1 in [testing]. I believe this is not needed with ruby-1.9 as rubygems is built in but I am not a ruby programmer so could be wrong...

we can close this now that ruby 1.9 is in testing?

It is now in [extra] so sure..