Selectively revert or checkout changes to a file in Git?

Question

Is there a command that allows you to partially undo the changes to a file (or files) in the working directory?

Suppose you have edited a file a lot but you realize that

Answer 1

You could use

git add -p 

to stage the chunks that you want to keep in a particular file, then

git checkout -- 

to discard the working tree changes that you didn't want to keep, by checking out the staged version of the file.

Finally, you can use

git reset -- 

to revert the staged version of the file to the most recent committed version of the file to leave you with your changes unstaged.