Why can I not commit? (Your branch is up-to-date with 'origin/master', no changes added to commit)

问题

I have been having some trouble committing a file to GitHub. I can make it to git add, but soon as I try $ git commit -m 'my message' I get an error, not allowing me to complete the process of adding a file.

$ git add HelloWorld.md

$ git commit -m 'Hello world'

I get the following answer (deleted: README.md & .DS_Store are in red):

On branch master

Your branch is up-to-date with 'origin/master'.

Changes not staged for commit:
        deleted:    README.md

Untracked files:
        .DS_Store

no changes added to commit

回答1:

If you changed the file but there is still nothing to commit, maybe you didn't add the file to git. (or replaced it after adding). Try adding the file before committing:

git add filename.ext

Or simply add the whole dir:

git add .

回答2:

Apparently you did not change anything in the HelloWorld.md file (or it doesn't exist at all), so there is nothing to commit. If you just want to add an "empty" file, make sure to touch HelloWorld.md first, so the file is actually created. If it does exist, edit it (using vim HelloWorld.md for example) and make sure to save the changes in your editor when you're done.

Once you've done that and there are actual changes to the file, you should be able to commit it.

回答3:

You have nothing to commit. More specifically:

README.md was a tracked file, but you deleted without using git rm README.md. Git detects that the file has been deleted, but you still have to stage that deletion if you want the latter to be effective in the next commit.
.DS_Store is an untracked file; as such, it cannot be part of the next commit. (By the way, you should ignore such files globally.)
git add HelloWorld.md has no effect: the file is being tracked by Git, but there is nothing to stage in there, because you simply haven't made any changes to it since the last commit.

How can I tell? If HelloWorld.md were a previously untracked file or if it were a tracked file which you changed since the last commit, git add HelloWorld.md would have successfully staged those changes; there would have been something to commit, and you would have been able to successfully commit.

Make some changes, stage them, and then you'll be able to commit. Finally,