Rubygems command not found - ruby

Question

Centos 7
I have installed ruby 2.1.2 and rubygems but when I run rubygems --version I get the error rubygems: command not found.
My $PATH is /usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/usr/local/lib/ruby/gems/2.1.0:/root/.gem/ruby/2.1.0
gem environment
RubyGems Environment:
- RUBYGEMS VERSION: 2.6.11
- RUBY VERSION: 2.1.2 (2014-05-08 patchlevel 95) [x86_64-linux]
- INSTALLATION DIRECTORY: /usr/local/lib/ruby/gems/2.1.0
- USER INSTALLATION DIRECTORY: /root/.gem/ruby/2.1.0
- RUBY EXECUTABLE: /usr/local/bin/ruby
- EXECUTABLE DIRECTORY: /usr/local/bin
- SPEC CACHE DIRECTORY: /root/.gem/specs
- SYSTEM CONFIGURATION DIRECTORY: /usr/local/etc
- RUBYGEMS PLATFORMS:
- ruby
- x86_64-linux
- GEM PATHS:
- /usr/local/lib/ruby/gems/2.1.0
- /root/.gem/ruby/2.1.0
- GEM CONFIGURATION:
- :update_sources => true
- :verbose => true
- :backtrace => false
- :bulk_threshold => 1000
- REMOTE SOURCES:
- https://rubygems.org/
- SHELL PATH:
- /usr/local/sbin
- /usr/local/bin
- /sbin
- /bin
- /usr/sbin
- /usr/bin
- /root/bin
- /root/ruby-2.1.2
- /usr/bin/gem
yum list installed shows rubygems.noarch
What do I need to do to get rubygems working?

Answer 1

To install ruby and rubygems on centOS, Run on Terminal
sudo yum install ruby
sudo yum install rubygems
To check version of of ruby and rubygems, Run
ruby -v
gem -v
Note: gem --version is same as gem -v
Update the gems list using :
sudo gem update
sudo gem update --system
Now, you can install any gem, using command
gem install <gem_name>
For instance, To install rails on centOS, Run
sudo gem install rails