origin - git reset--hard orig_head
Why git can't do hard/soft resets by path? (3)
Because there's no point (other commands provide that functionality already), and it reduces the potential for doing the wrong thing by accident.
A "hard reset" for a path is just done with
git checkout HEAD -- <path> (checking out the existing version of the file).
A soft reset for a path doesn't make sense.
A mixed reset for a path is what
git reset -- <path> does.
$ git reset -- <file_path> can reset by path.
$ git reset (--hard|--soft) <file_path> will report an error like below:
Cannot do hard|soft reset with paths.
The question how is already answered, I'll explain the why part.
So, what does git reset do? Depending on the parameters specified, it can do two different things:
If you specify a path, it replaces the matched files in the index with the files from a commit (HEAD by default). This action doesn't affect the working tree at all and is usually used as the opposite of git add.
If you don't specify a path, it moves the current branch head to a specified commit and, together with that, optionally resets the index and the working tree to the state of that commit. This additional behavior is controlled by the mode parameter:
--soft: don't touch the index and the working tree.
--mixed (default): reset the index but not the working tree.
--hard: reset the index and the working tree.
There are also other options, see the documentation for the full list and some use cases.
When you don't specify a commit, it defaults to HEAD, so
git reset --softwill do nothing, as it is a command to move the head to HEAD (to its current state).
git reset --hard, on the other hand, makes sense due to its side effects, it says move the head to HEAD and reset the index and the working tree to HEAD.
I think it should be clear by now why this operation is not for specific files by its nature - it is intended to move a branch head in the first place, resetting the working tree and the index is secondary functionality.
git reset --soft HEAD~1 filename undo the commit but changes remain in local. filename could be -- for all commited files