ooh good call, thanks! Added.
With more recent versions of rvm (where recently may be over a year, not sure), you can shorten the rvm commands (lines 18-21) to:
rvm use --create --rvmrc 1.9.3-p125@msf
I was once again reminded that I'm not "with the times" on gemset management.
Here's the newer more cross-functional way, although, I'm not a fan of it's invocation, it's definitely more persistent if you need to blow your RVM env away:
echo "gem_set_name" > .ruby-gemset
echo "ruby-2.1.2" > .ruby-version
This of course is done in the root dir of the project.
An even "better" way...
rvm --create --ruby-version use ruby-2.0.0-p247@mycoolapp