Q:

Why can't RVM find compiler and 'make' tool after installing XCode?

I installed RVM on OS X 10.8.3. The command rvm -v works but there was one error when I tried to execute the following code:
\curl -L https://get.rvm.io | bash -s stable --rails # Or, --ruby=2.0.0-p195

Here is the error:

rvm 1.20.13 (stable) by Wayne E. Seguin , Michal Papis  [https://rvm.io/]

Searching for binary rubies, this might take some time.
No binary rubies available for: osx/10.8/x86_64/ruby-2.0.0-p195.
Continuing with compilation. Please read 'rvm mount' to get more information on binary rubies.
Installing requirements for osx, might require sudo password.

    Can not find compiler and 'make' tool - make sure Xcode and/or Command Line Tools are installed.

I even tried  rvm install 1.9.2 but the same error showed up. I also installed Xcode with no luck. 

A:

It looks like you have installed Xcode, but not the command line tools that RVM requires to build Ruby and other components (make, gcc, etc)
Here are some instructions (taken from this answer):

Xcode includes a new "Downloads" preference pane to install optional
  components such as command line tools, and previous iOS Simulators. 
  To open this pane click the "Xcode" button in the top left of the
  screen near the Apple logo, then click "Preferences", then click
  "Downloads".

Then install the 'Command Line Tools' bundle by clicking the Install button to the right of it.

A:

For Xcode 5 it's
Xcode -> Preferences -> Download -> Command Line Tools

