Why does git checkout not delete new files?

Question

Suppose I create (but do not commit) a file file.txt, and then type git checkout HEAD or git checkout HEAD .. I thought git checkout basically overwrote your current working files with the snapshot at the commit you give it, so I would have thought this would delete file.txt. But it doesn't. Why?

Answer 1

git checkout doesn't overwrite your working copy by-design.

It works in the same way as git reset --hard but with the important difference - git checkout is working-directory safe, so it doesn't overwrite existing changes in your working directory. Actually, it’s a bit smarter — it tries to do a trivial merge in the working directory.

So, if you want to discard all of your changes and just get the snapshot from HEAD use git reset --hard HEAD or just git reset --hard instead.

But even git reset --hard doesn't remove your untracked files. To remove untracked files:

• Run git clean --dry-run. It just tells you what will be removed. Do it because cleaning is a dangerous command.
• Run git clean --force to eventually remove your untracked files.

You can find more details about git checkout and git reset here and about cleaning here.

Answer 2

file.txt, being untracked, is "invisible" to Git. If there is another file named file.txt in the commit you check out, it can be overwritten as a side effect of the check out, but Git won't go out of its way to removed untracked files.