Git remote add with other SSH port

Another way to make a directory stay (almost) empty (in the repository) is to create a .gitignore file inside that directory that contains these four lines:

# Ignore everything in this directory
*
# Except this file
!.gitignore

Then you don't have to get the order right the way that you have to do in m104's solution.

This also gives the benefit that files in that directory won't show up as "untracked" when you do a git status.

Making @GreenAsJade's comment persistent:

I think it's worth noting that this solution does precisely what the question asked for, but is not perhaps what many people looking at this question will have been looking for. This solution guarantees that the directory remains empty. It says "I truly never want files checked in here". As opposed to "I don't have any files to check in here, yet, but I need the directory here, files may be coming later".

You can undo git add before commit with

git reset <file>

which will remove it from the current index (the "about to be committed" list) without changing anything else.

You can use

git reset

without any file name to unstage all due changes. This can come in handy when there are too many files to be listed one by one in a reasonable amount of time.

In old versions of Git, the above commands are equivalent to git reset HEAD <file> and git reset HEAD respectively, and will fail if HEAD is undefined (because you haven't yet made any commits in your repository) or ambiguous (because you created a branch called HEAD, which is a stupid thing that you shouldn't do). This was changed in Git 1.8.2, though, so in modern versions of Git you can use the commands above even prior to making your first commit:

"git reset" (without options or parameters) used to error out when you do not have any commits in your history, but it now gives you an empty index (to match non-existent commit you are not even on).

Documentation: git reset