.gitignore exclude folder but include specific subfolder

Question

I have the folder application/ which I add to the .gitignore. Inside the application/ folder is the folder application/language

Answer 1

Commit 59856de from Karsten Blees (kblees) for Git 1.9/2.0 (Q1 2014) clarifies that case:

gitignore.txt: clarify recursive nature of excluded directories

An optional prefix "!" which negates the pattern; any matching file excluded by a previous pattern will become included again.

It is not possible to re-include a file if a parent directory of that file is excluded. (*)
(*: unless certain conditions are met in git 2.8+, see below)
Git doesn't list excluded directories for performance reasons, so any patterns on contained files have no effect, no matter where they are defined.

Put a backslash ("\") in front of the first "!" for patterns that begin with a literal "!", for example, "\!important!.txt".

Example to exclude everything except a specific directory foo/bar (note the /* - without the slash, the wildcard would also exclude everything within foo/bar):

 --------------------------------------------------------------
     $ cat .gitignore
     # exclude everything except directory foo/bar
     /*
     !/foo
     /foo/*
     !/foo/bar
 --------------------------------------------------------------

In your case:

application/*
!application/**/
application/language/*
!application/language/**/
!application/language/gr/**

You must white-list folders first, before being able to white-list files within a given folder.

---

Update Feb/March 2016:

Note that with git 2.9.x/2.10 (mid 2016?), it might be possible to re-include a file if a parent directory of that file is excluded if there is no wildcard in the path re-included.

Nguyễn Thái Ngọc Duy (pclouds) is trying to add this feature:

• commit 506d8f1 for git v2.7.0, reverted in commit 76b620d git v2.8.0-rc0
• commit 5e57f9c git v2.8.0-rc0,... reverted(!) in commit 5cee3493 git 2.8.0.

So with git 2.9+, this could have actually worked, but was ultimately reverted:

application/
!application/language/gr/