Git reset single file in feature branch to be the same as in master [duplicate]

Question 1

I'm trying to revert my changes in a single file in my feature branch and I want this file to be the same as in master.

I tried:

git checkout -- filename
git checkout filename 
git checkout HEAD -- filename

It seems that none of these made any changes to my feature branch. Any suggestions?

Question 2

If you want to revert the file to its state in master:

git checkout origin/master [filename]

Question