Git: Ignore All Contents of a Directory but the Directory Itself

You sometime want to ignore all contents of a directory but the directory itself in a commitment, such as cache/ directory for example. It can both reduce the amount of data and temporary files to be stored in the repository.

In case of Git, all you need is to create a .gitignore file inside the cache/ directory with  the content as follows.

*
!.gitignore

The first line tells Git to ignore all contents, but the second line tells Git to keep the file .gitignore, and therefore, keeps it to be a non-empty directory.