Why am I getting "rvm: command not found" on Ubuntu?

The problem is that the commands rvm and rvmsudo are not in your PATH. The PATH is a variable that lists all of the directories that are searched for commands.

You need to find out where the rvm and rvmsudo commands are actually located; it could be in /usr/local somewhere or in /opt. If the RVM software was installed in /usr/local I would guess that it would work just fine; check /opt.

Then add the directories that contain commands to your PATH (on the command line and in .profile):

export PATH=$PATH:/opt/rvm/bin:/opt/rvm/sbin

(The directories are just examples.) Using $PATH preserves your current PATH and adds the two new directories on the end. Directories are searched from left to right and are separated by :.

More on this can be found in man bash or man sh or man ksh depending on your shell.

On Ubuntu you need to use ~/.bashrc instead of ~/.bash_profile in case if per user installations, So do:

echo '[[ -s "$HOME/.rvm/scripts/rvm" ]] && . "$HOME/.rvm/scripts/rvm" # Load RVM function' >> ~/.bashrc

or if you're using ubuntu 12.04:

echo '[[ -s "/usr/local/rvm/scripts/rvm" ]] && . "/usr/local/rvm/scripts/rvm" # Load RVM function' >> ~/.bashrc

and after that:

source ~/.bashrc

and test with:

type rvm | head -1

you should get: rvm is a function