[ruby] CentOS に gem が入っていなかったときのインストールメモ

#
# cat /etc/redhat-release
#
CentOS release 6.4 (Final)

#
# yum install ruby
# ruby -v
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ruby 1.8.7 (2011-06-30 patchlevel 352) [x86_64-linux]

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# git clone https://github.com/rubygems/rubygems.git rubygems
#
Initialized empty Git repository in /root/Documents/rubygems/.git/
remote: Counting objects: 38455, done.
remote: Compressing objects: 100% (17834/17834), done.
remote: Total 38455 (delta 22413), reused 34895 (delta 18918)
Receiving objects: 100% (38455/38455), 12.63 MiB | 144 KiB/s, done.
Resolving deltas: 100% (22413/22413), done.

#
# cd rubygems
# ruby setup.rb
#
RubyGems 2.2.0 installed
ERROR:  While executing gem ... (Gem::DocumentError)
    RDoc is not installed: no such file to load -- rdoc/rdoc

#
# yum install rdoc
# rdoc -v
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RDoc V1.0.1 - 20041108

#
# ruby setup.rb
#
RubyGems 2.2.0 installed
Installing ri documentation for rubygems-2.2.0
/usr/lib/ruby/1.8/rdoc/rdoc.rb:280: warning: conflicting chdir during another chdir block
/usr/lib/ruby/1.8/rdoc/rdoc.rb:287: warning: conflicting chdir during another chdir block



------------------------------------------------------------------------------

RubyGems installed the following executables:
        /usr/bin/gem

Ruby Interactive (ri) documentation was installed. ri is kind of like man
pages for ruby libraries. You may access it like this:
  ri Classname
  ri Classname.class_method
  ri Classname#instance_method
If you do not wish to install this documentation in the future, use the
--no-document flag, or set it as the default in your ~/.gemrc file. See
'gem help env' for details.


#
# gem -v
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2.2.0

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# gem install sass
#
Fetching: sass-3.2.12.gem (100%)
Successfully installed sass-3.2.12
Installing ri documentation for sass-3.2.12
/usr/lib/ruby/1.8/rdoc/rdoc.rb:280: warning: conflicting chdir during another chdir block
/usr/lib/ruby/1.8/rdoc/rdoc.rb:287: warning: conflicting chdir during another chdir block
Done installing documentation for sass after 42 seconds
1 gem installed

#
# sass -v
#
Sass 3.2.12 (Media Mark)

以上。

追記:2015-01-19

もっと簡単でした。

# yum install rubygems