Error when run "gem install rails"

Question

My configuration:

• Operating System: Ubuntu 12.04
• rvm version: 1.25.14
• ruby version: 2.1.0p0

• gem version: 2.2.1

  $ which ruby /home/tauhidul35/.rvm/rubies/ruby-2.1.0/bin/ruby $ which rvm /home/tauhidul35/.rvm/bin/rvm $ which gem /home/tauhidul35/.rvm/rubies/ruby-2.1.0/bin/gem $ which bundle /home/tauhidul35/.rvm/gems/ruby-2.1.0@global/bin/bundle

Now when I run command, I get error:

$ gem install rails
ERROR:  While executing gem ... (NoMethodError)
undefined method `ord' for nil:NilClass

If I run command, I get error:

$ sudo apt-get install rails
E: Unable to locate package rails

I am new in Ubuntu and also Ruby on Rails. Please help me.

Answer 1

Thanks to all for your help.
At last this problem is solved, when I update my computer using Ubuntu Update Manager.
I don't know why solved the problem after updates. But I am sure it is solved by Updating all.

Specially thanks to majioa.

Answer 2

Remember that you can also 'get certain' of your ruby and gem situation by installing a new ruby with a new gemset.

You can use rbenv to install a ruby and gemset to a local path over which you have full permission control, so that you can remove, reinstall, etc. them any time.

You can install a ruby manager like rbenv by following the instructions here