Remove previously commit files in update .gitignore - ala http://stackoverflow.com/questions/7527982/applying-gitignore-to-committed-files

gistfile1.txt

After editing .gitignore to match the ignored files, you can do git ls-files -ci --exclude-standard to see the files that are included in the exclude lists; you can then do git ls-files -ci --exclude-standard -z | xargs -0 git rm --cached to remove them from the repository (without deleting them from disk).

Edit: You can also add this as an alias in your .gitconfig file so you can run it anytime you like. Just add the following line under the [alias] section:

    apply-gitignore = !git ls-files -ci --exclude-standard -z | xargs -0r git rm --cached
(The -r flag in xargs prevents git rm from running on an empty result and printing out its usage message.)

Now you can just type git apply-gitignore in your repo, and it'll do the work for you!