RVM is not a function, selecting rubies with 'rvm use ...' will not work.

To fix this in Ubuntu 12.04, go to : Profile --> Preferences, Title and Command tab and check the box for 'Run command as a login shell'

Installing RVM on Ubuntu 12.04

1. sudo apt-get install curl
2. \curl -L https://get.rvm.io | bash -s stable
3. source ~/.rvm/scripts/rvm

Do not run OS updates in parallel when installing RVM.



Reference:
Install Ruby on Rails on Ubuntu 12.04

how to setup Textmate 2 to run mate from command line

Go to preferences --> Terminal and click 'Install' to install shell support.

If you get the error 'To open a bundled gem, set $EDITOR or $BUNDLER_EDITOR'
Add the following line to ~/.bash_profile:

export BUNDLER_EDITOR=mate

Setup Textmate 2 to use RVM

1. $ which rvm-auto-ruby
2. Add the following to ~/.tm_properties

TM_RUBY="/path/to/rvm-auto-ruby/from/step1/"

3. Restart Textmate 2
4. Run : puts RUBY_VERSION as a ruby file.