 <p>What I do on my squeeze boxes to get ruby 1.9 as default:</p> <pre><code>cd /usr/bin ln -sf ruby1.9.1 ruby ln -sf gem1.9.1 gem ln -sf erb1.9.1 erb ln -sf irb1.9.1 irb ln -sf rake1.9.1 rake ln -sf rdoc1.9.1 rdoc ln -sf testrb1.9.1 testrb </code></pre> <p>I run a lot of rails production servers this way and all other debian ruby packages are not broken because they relay on /usr/bin/ruby1.8 binary.</p> <p>This not "true debian way" but for some reason <code>update-alternatives</code> does not support configuring ruby in squeeze.</p> <p>In Ubuntu 11.10 you can just run <code>update-alternatives --config ruby</code> and selected desired version</p> <p>I also recommend you to update rubygems before you start installing any gems <code>REALLY_GEM_UPDATE_SYSTEM=true gem update --system</code></p>