Make .gitignore ignore everything except a few files

An optional prefix ! which negates the pattern; any matching file excluded by a previous pattern will become included again. If a negated pattern matches, this will override lower precedence patterns sources.

# Ignore everything
*

# But not these files...
!.gitignore
!script.pl
!template.latex
# etc...

# ...even if they are in subdirectories
!*/

# if the files to be tracked are in subdirectories
!*/a/b/file1.txt
!*/a/b/c/*

If you want to ignore the whole content of a directory except one file inside it, you could write a pair of rules for each directory in the file path. E.g. .gitignore to ignore the pippo folder except from pippo/pluto/paperino.xml

pippo/*
!pippo/pluto
pippo/pluto/*
!pippo/pluto/paperino.xml

---

Note that if you simply had written above:

pippo/*
!pippo/pluto/paperino.xml

It wouldn't work because the intermediary pluto folder would not exist to Git, so paperino.xml could not find a place in which to exist.