Create a .gitignore file after creating a new rails app and BEFORE committing! http://stackoverflow.com/questions/1274057/making-git-forget-about-a-file-that-was-tracked-but-is-now-in-gitignore See here for more info: https://help.github.com/articles/ignoring-files

gitignore

Create a local .gitignore

If you create a file in your repository named .gitignore, Git uses it to determine which files and directories to ignore, before you make a commit.

A .gitignore file should be committed into your repository, in order to share the ignore rules with any other users that clone the repository.

GitHub maintains an official list of recommended .gitignore files for many popular operating systems, environments, and languages in the github/gitignore public repository.

In Terminal, navigate to the location of your Git repository.
Enter: touch .gitignore to create a .gitignore file.
The Octocat has a Gist containing some good rules to add to this file.

If you already have a file checked in, and you want to ignore it, Git will not ignore the file if you add a rule later. In those cases, you must untrack the file first, by running the following command in your terminal:

1. git rm -r --cached . 
2. git add .
3. git commit -am "Remove ignored files"
4. push to master

Rules for the .gitignore file:

*.rbc
capybara-*.html
.rspec
/log
/tmp
/db/*.sqlite3
/public/system
/coverage/
/spec/tmp
**.orig
rerun.txt
pickle-email-*.html

# TODO Comment out these rules if you are OK with secrets being uploaded to the repo
config/initializers/secret_token.rb
config/secrets.yml

## Environment normalisation:
/.bundle
/vendor/bundle

# these should all be checked in to normalise the environment:
# Gemfile.lock, .ruby-version, .ruby-gemset

# unless supporting rvm < 1.11.0 or doing something fancy, ignore this:
.rvmrc

# if using bower-rails ignore default bower_components path bower.json files
/vendor/assets/bower_components
*.bowerrc
bower.json