Question: I installed RVM, Ruby 1.9.2 and Rails 3.0.9 on Lion which works fine. Only problem is, after I close the terminal I need to execute this: 

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

```

for it to pick up RVM.I then need to make RVM use Ruby 1.9.2 first before I can do Rails stuff again.

How can I make this permanent?

Answer: 
After you first execute 

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

```

you shouldn't need to do it again. That line appends the necessary file inclusion information RVM into your `.bash_profile`. If you are using `bash` (as opposed to zsh, ksh, csh, tcsh or any other shell), then RVM will be accessible each time you open a new session. If you are using a different shell, that line may need to be in a different startup file. For example, if you are using zsh, then you'll probably want to append it to your `~/.zshrc` file. 

Having done this, simply running `rvm --default use ruby-1.9.2` once should ensure that you have the desired version of Ruby by default. Note, you should not need to add this line to your `.bash_profile` or similar.
In order to make Terminal (e.g. bash) enable RVM every time you open it, edit `~/.profile` and add the following line to it:

```
[[ -s "/Users/foo/.rvm/scripts/rvm" ]] && source "/Users/foo/.rvm/scripts/rvm"  # This loads RVM into a shell session.

```

Then to make the RVM's version of ruby default, as fl00r has mentioned, run:

```
rvm --default use ruby-1.9.2

```

Alternatively, you can add an `.rvmrc` file to the root folder of your app that uses Rails 3.0.9 and specify which version of Ruby you want to use with that project there:

```
rvm ruby-1.9.2

```

Even better, you should create a gemset by running `rvm gemset create rails-3.0.9` and update you `.rvmrc` file to become like this:

```
rvm ruby-1.9.2@rails-3.0.9

```

Then run cd into the project once again (you must cd into it once again), and run bundle install.

This way your project will have its own isolated gemset.