how to use .gitignore reverse select

Question

use .gitignore to reverse selection,I just want to track the app catalog.App is the secondary directory under emply.

l used The following code,But git doesn't track anything

*
!*/
!*/app

I have already tested similar problems, Write like it, but invalid

Answer 1

I just had a slightly more tricky problem and ended up here, so if this is the case for you as well, here goes:

If you ignore a concrete directory (e.g. /Emply/ in this case) but want to include some of its sub-directories or included files, this will not work:

/Emply/
!/Emply/app  # Does not work!

The reason is that git will not list ignored directories for performance reasons (source). Instead, use the wildcard to ignore all sibling directories and files:

/Emply/*
!/Emply/app  # Works!

It's a bit obscure and just drove me mad.

Answer 2

Ignore everything, unignore top-level app and everything under it:

*
!/app/
!/app/*