Example
The checked out file will overwrite not yet commited changes you did in this file.
This command will check out the file file.example (which is located in the directory path/to/) and overwrite any changes you might have made to this file.
git checkout some-branch path/to/file
some-branch can be anything tree-ish known to git (see Revision Selection and gitrevisions for more details)
You have to add -- before the path if your file could be mistaken for a file (optional otherwise). No more options can be supplied after the --.
git checkout some-branch -- some-file
The second some-file is a file in this example.
