$sudo apt-get install ruby rubygems
...
$ruby -v
ruby 1.8.7 (2010-06-23 patchlevel 299) [i686-linux]
$gem -v
1.3.7

如果我尝试安装Rails,我得到一个错误,即使它似乎只是文档,rails没有安装：

$sudo gem install rails
...
Successfully installed rails-3.0.1
24 gems installed
... 
Installing ri documentation for builder-2.1.2...
ERROR:  While generating documentation for builder-2.1.2
... MESSAGE:   Unhandled special: Special: type=17,text="<!-- HI -->"
... RDOC args: --ri --op /var/lib/gems/1.8/doc/builder-2.1.2/ri --title Builder -- Easy XML Building --main README --line-numbers --quiet lib CHANGES Rakefile README doc/releases/builder-1.2.4.rdoc doc/releases/builder-2.0.0.rdoc doc/releases/builder-2.1.1.rdoc --title builder-2.1.2 Documentation
(continuing with the rest of the installation)
...
Installing ri documentation for rails-3.0.1...
File not found: lib

$rails -v
The program 'rails' is currently not installed.  You can install it by typing:
sudo apt-get install rails

Ubuntu存储库只有Rails 2.3.5,所以不是一个选项.

如何让Rails正确安装？

更新：我试过以下,这次没有错,但还是没有成功：

$sudo gem install rails --no-rdoc --no-ri
Successfully installed rails-3.0.1
1 gem installed
$rails -v
The program 'rails' is currently not installed...

更新2：所以,感谢Maran和Jörg,现在我知道问题不在于没有安装rails,但是没有添加到PATH中.这可以通过在〜/ .bashrc中添加以下内容来修复：

export PATH=/var/lib/gems/1.8/bin:$PATH

这又提出了一个问题：PATH应该添加什么？大概apt-get安装rubygems？还有什么可以打破？