Mac OS X Mountain Lion "Rails is not currently installed on this system."

Use RVM http://rvm.io or rbenv to install newer Rails versions than what come pre-installed with OS X.

Follow examples on the site https://rvm.io/rvm/install/ but basically:

Install RVM: $ \curl -L https://get.rvm.io | bash -s stable

You can then $rvm list known to see what Rubies are available to you (lots). And simply $rvm install 1.9.3 to get the most current version of Ruby (which as of this writing is ruby-1.9.3-p327)

Set that ruby as your default $rvm --default use 1.9.3

Create a default gemset to store your gems $rvm use 1.9.3@mygemset --create --default

Then install Rails $ gem install rails will get you current which today is same as typing gem install rails -v 3.2.9

If you're using rbenv, don't forget to rbenv rehash after installing/updating ruby.

Just had this issue using rbenv, no idea how this happened, but figured that my ~/.rbenv/shims/rails was empty...

So to fix this:

• Cleaned empty shims: find ~/.rbenv/shims -empty -delete

• Then regenerate: rbenv rehash (was not overwriting empty one...)