git undo all uncommitted or unsaved changes

• This will unstage all files you might have staged with git add:

  git reset
  

• This will revert all local uncommitted changes (should be executed in repo root):

  git checkout .
  

  You can also revert uncommitted changes only to particular file or directory:

  git checkout [some_dir|file.txt]
  

  Yet another way to revert all uncommitted changes (longer to type, but works from any subdirectory):

  git reset --hard HEAD
  

• This will remove all local untracked files, so only git tracked files remain:

  git clean -fdx
  

  WARNING: -x will also remove all ignored files, including ones specified by .gitignore! You may want to use -n for preview of files to be deleted.

To sum it up: executing commands below is basically equivalent to fresh git clone from original source (but it does not re-download anything, so is much faster):

git reset
git checkout .
git clean -fdx

Typical usage for this would be in build scripts, when you must make sure that your tree is absolutely clean – does not have any modifications or locally created object files or build artefacts, and you want to make it work very fast and to not re-clone whole repository every single time.