Temporarily ignoring files in GIT

From [http://gitready.com/intermediate/2009/02/18/temporarily-ignoring-files.html]

This prevents the changes to a file in the local repository to be pushed to the remote repository.

temporarily ignoring files

committed 18 Feb 2009

Usually ignoring files is quite simple with Git. However, you may need to quickly hide changes in a file, perhaps for an entire development session or other reasons. Luckily there’s a simple way around this, thanks to some clever manual diving from Eelco Wiersma.

His main problem was using git commit -a, which automatically adds files that are modified into the commit object. This is a neat shortcut, but make sure you understand the staging area if you find yourself running this command all the time.

So, to temporarily ignore changes in a certain file, run:

git update-index --assume-unchanged <file>

Then when you want to track changes again:

git update-index --no-assume-unchanged <file>

Obviously there’s quite a few caveats that come into play with this. If you git add the file directly, it will be added to the index. Merging a commit with this flag on will cause the merge to fail gracefully so you can handle it manually.

Let’s go over a quick example of using the command. Changes have been made to a few files in my working directory:

$ git status
# On branch master
#
# Changed but not updated:
#   (use "git add <file>..." to update what will be committed)
#
# modified:   README.textile
# modified:   Rakefile
# modified:   TODO
#
no changes added to commit (use "git add" and/or "git commit -a")

If I ran git commit -a from here, all of the files would be added into the new commit. However, I want to temporarily ignore the changes in one of the files:

$ git update-index --assume-unchanged README.textile   
$ git status
# On branch master
#
# Changed but not updated:
#   (use "git add <file>..." to update what will be committed)
#
# modified:   Rakefile
# modified:   TODO
#
no changes added to commit (use "git add" and/or "git commit -a")

So if we commit the work now then turn the flag off, we can see that Git didn’t lose the original changes to the README. From there, you could now add them into a new commit, or revert back to the latest copy.

$ git update-index --no-assume-unchanged README.textile
$ git status
# On branch master
# Your branch is ahead of 'origin/master' by 4 commits.
#
# Changed but not updated:
#   (use "git add <file>..." to update what will be committed)
#
# modified:   README.textile
#
no changes added to commit (use "git add" and/or "git commit -a")

Check out the man page for git update-index here. If you know of other clever tricks with the index, leave a comment or submit a tip!