Fix a Git detached head?

Question

I was doing some work in my repository and noticed a file had local changes. I didn\'t want them anymore so I deleted the file, thinking I can just checkout a fresh copy. I

Answer 1

When you check out a specific commit in git, you end up in a detached head state...that is, your working copy no longer reflects the state of a named reference (like "master"). This is useful for examining the past state of the repository, but not what you want if you're actually trying to revert changes.

If you have made changes to a particular file and you simply want to discard them, you can use the checkout command like this:

git checkout myfile

This will discard any uncommitted changes and revert the file to whatever state it has in the head of your current branch. If you want to discard changes that you have already committed, you may want to use the reset command. For example, this will reset the repository to the state of the previous commit, discarding any subsequent changes:

git reset --hard HEAD^

However, if you are sharing the repository with other people, a git reset can be disruptive (because it erases a portion of the repository history). If you have already shared changes with other people, you generally want to look at git revert instead, which generates an "anticommit" -- that is, it creates a new commit that "undoes" the changes in question.

The Git Book has more details.