How to .gitignore all files/folder in a folder, but not the folder itself?

Put this .gitignore into the folder, then git add .gitignore.

*
*/
!.gitignore

The * line tells git to ignore all files in the folder, but !.gitignore tells git to still include the .gitignore file. This way, your local repository and any other clones of the repository all get both the empty folder and the .gitignore it needs.

Edit: May be obvious but also add */ to the .gitignore to also ignore subfolders.

You can't commit empty folders in git. If you want it to show up, you need to put something in it, even just an empty file.

For example, add an empty file called .gitkeep to the folder you want to keep, then in your .gitignore file write:

# exclude everything
somefolder/*

# exception to the rule
!somefolder/.gitkeep 

Commit your .gitignore and .gitkeep files and this should resolve your issue.