Hard reset of a single file

Solution 1:

You can use the following command:

git checkout HEAD -- my-file.txt

... which will update both the working copy of my-file.txt and its state in the index with that from HEAD.

-- basically means: treat every argument after this point as a file name. More details in this answer. Thanks to VonC for pointing this out.

Solution 2:

Reset to head:

To hard reset a single file to HEAD:

git checkout @ -- myfile.ext

Note that @ is short for HEAD. An older version of git may not support the short form.

Reset to index:

To hard reset a single file to the index, assuming the index is non-empty, otherwise to HEAD:

git checkout -- myfile.ext

The point is that to be safe, you don't want to leave out @ or HEAD from the command unless you specifically mean to reset to the index only.