How can I reset or revert a file to a specific revision?

Question

I have made some changes to a file which has been committed a few times as part of a group of files, but now want to reset/revert the changes on it back to a previous versio

Answer 1

Obviously someone either needs to write an intelligible book on git, or git needs to be better explained in the documentation. Faced with this same problem I guessed that

cd 
git revert master

would undo the last commit which is seemed to do.

Ian