rails_admin.git installation problem or more general problem

i want to install this https://github.com/sferik/rails_admin so i pasting those 2 in the gemfile

gem 'devise' # Devise must be required before RailsAdmin

gem 'rails_admin', :git => 'git://github.com/sferik/rails_admin.git'

however when i bundle install, the second one alone seems to give this problem:

Fetching git://github.com/sferik/rails_admin.git
sh: git: command not found
An error has occurred in git when runn开发者_JAVA技巧ing `git clone "git://github.com/sferik/rails_admin.git" "/Library/Ruby/Gems/1.8/cache/bundler/git/rails_admin-76c2c78f1892a43807d922e810aef4edcddc12b7" --bare --no-hardlinks`. Cannot complete bundling.

Any ideas?

It doesn't appear as if you have git installed. Please follow the GitHub guide for installing it on your operating system.