While installing Rails on a fresh Linux Mint (17) I could not start gem, rvm and ruby from the console. For the installation I followed the usual guides on https://rvm.io/rvm/install. When I tried to start gem, rvm or ruby an error message displayed they could not be found and should be installed. This problem may occur because the genome terminal Mint and Ubuntu use needs one additional configuration to run rvm, gem and ruby:
Open the terminal and go to Edit > Profile Preferences
Choose the tab Title and Command and make sure Run command as a login shell is activated.
Now everything works without any problems.