What does __FILE__ mean in Ruby?

Question

I see this all the time in Ruby:

require File.dirname(__FILE__) + \"/../../config/environment\"  

What does __FILE__ mean?

Answer 1

__FILE__ is the filename with extension of the file containing the code being executed.

In foo.rb, __FILE__ would be "foo.rb".

If foo.rb were in the dir /home/josh then File.dirname(__FILE__) would return /home/josh.