Before committing, I see with git diff that I've made a change that I would rather not have made. Is there any way to revert this single change?
I suppose that I could use git add -p to commit the changes that I did intend to make, and then to checkout master. Is there a better way, preferably a way that does not require me to commit?
This is with Git 1.7.10.4 on Kubuntu Linux 12.10. Thanks!
git reset --patch (or git reset -p) does what you want.
The relevant bit of the documentation:
git reset (--patch | -p) [] [--] […]
Interactively select hunks in the difference between the index and (defaults to HEAD). The chosen hunks are applied in reverse to the index.
This means that git reset -p is the opposite of git add -p, i.e. you can use it to selectively reset hunks. See the “Interactive Mode” section of git-add(1) to learn how to operate the --patch mode.
Note that git reset (applied on paths) does match git add — the latter stages files or chunks while the former unstages them, and so git reset supports the --patch option just like git add does.
You might also be interested to learn about git checkout --patch (or git checkout -p).