This post goes over the difference between git checkout, git clean, and git reset:
They will be compared using the example below.
Example
Given the index and working tree:
git status
On branch master
Changes not staged for commit:
(use "git add <file>..." to update what will be committed)
(use "git checkout -- <file>..." to discard changes in working directory)
modified: modified.txt
Untracked files:
(use "git add <file>..." to include in what will be committed)
untracked.txt
no changes added to commit (use "git add" and/or "git commit -a")
Or in the short format:
git status -s
M modified.txt
?? untracked.txt
git checkout
Changes to modified files are discarded but untracked files are untouched:
git checkout .
git status -s
?? untracked.txt
See docs on git checkout for more info.
git clean
Untracked files are removed but modified files are unchanged:
git clean -f
Removing untracked.txt
git status -s
M modified.txt
To remove untracked directories in addition to untracked files, run:
git clean -f -d
See docs on git clean for more info.
git reset
Changes to modified files are discarded but untracked files are untouched:
git reset --hard
HEAD is now at sha1234 my commit message
git status -s
?? untracked.txt
Thus, to discard modified files and remove untracked files:
git reset --hard && git clean -f -d
See docs git reset for more info.