I started trying to set up a local rails installation for development.  After I installed in using apt-get, however, I learned about RVM, so I removed the earlier one, and reinstalled from RVM.  It looks like I have residual problems, though.  Specifically, when I try to install rails I get...
$ gem install rails
ERROR:  While executing gem ... (Gem::FilePermissionError)
    You don't have write permissions into the /var/lib/gems/1.9.1 directory.
This already looks like a problem, because I don't want it to be in the /var/ directory, I want it to be in the user directory. So, I check the following...
$ gem env
RubyGems Environment:
  - RUBYGEMS VERSION: 1.8.11
  - RUBY VERSION: 1.9.3 (2011-10-30 patchlevel 0) [x86_64-linux]
  - INSTALLATION DIRECTORY: /var/lib/gems/1.9.1
  - RUBY EXECUTABLE: /usr/bin/ruby1.9.1
  - EXECUTABLE DIRECTORY: /usr/local/bin
  - RUBYGEMS PLATFORMS:
    - ruby
    - x86_64-linux
  - GEM PATHS:
     - /var/lib/gems/1.9.1
     - /home/myusername/.gem/ruby/1.9.1
  - GEM CONFIGURATION:
     - :update_sources => true
     - :verbose => true
     - :benchmark => false
     - :backtrace => false
     - :bulk_threshold => 1000
  - REMOTE SOURCES:
     - http://rubygems.org/
As well as sudo'd:
$ sudo gem env
RubyGems Environment:
  - RUBYGEMS VERSION: 1.8.11
  - RUBY VERSION: 1.9.3 (2011-10-30 patchlevel 0) [x86_64-linux]
  - INSTALLATION DIRECTORY: /var/lib/gems/1.9.1
  - RUBY EXECUTABLE: /usr/bin/ruby1.9.1
  - EXECUTABLE DIRECTORY: /usr/local/bin
  - RUBYGEMS PLATFORMS:
    - ruby
    - x86_64-linux
  - GEM PATHS:
     - /var/lib/gems/1.9.1
     - /home/myusername/.gem/ruby/1.9.1
  - GEM CONFIGURATION:
     - :update_sources => true
     - :verbose => true
     - :benchmark => false
     - :backtrace => false
     - :bulk_threshold => 1000
  - REMOTE SOURCES:
     - http://rubygems.org/
gems seem to live in /var/lib for some reason. Is this normal? How can I fix this so I can install the rails gem?
EDIT: UPDATE!
It appears to me that I have gems installed twice, once in /var/lib/gems/1.9.91 (bad) and once in /home/myusername/.gem/ruby/1.9.1 (good).
I think what is happening here is that when I type "gem" the installation in /var/lib/gems/1.9.1 (bad) is taking priority over /home/myusername/.gem/ruby/1.9.1 (good). Can anyone confirm that? Also, would it be OK and fix things just to delete the bad directory, or would that cause problems?
 
     
    