What if you accidentally committed
file.txt, which you didn’t intend to commit:
$ git commit -am "Commit all files"
How do you revert the file to its previous state before the commit?
The quick solution is to undo your last commit:
$ git reset HEAD~
However, you’ll need to recommit everything all over again.
Alternatively, you could checkout the file at a state before it was committed:
$ git checkout HEAD~ -- file.txt
Then amend your commit:
$ git commit --amend