Gitignore - Exclude all except specific subdirectory

.gitignore

#
# If all files excluded and you will include only specific sub-directories
# the parent path must matched before.
#

/**
!/.gitignore

###############################
# Un-ignore the affected subdirectory
!/libraries/
# Ignore subdirectory and all including directories and files to match pattern as valid for the next pattern
/libraries/**
# This pattern only works with the two previous patterns
# (i remember it was working alone on older git versions)
!/libraries/myLibrary/
###############################

# Another example
!/templates/
/templates/**
!/templates/myTemplate/

Thank you!
I wanted to share my example, maybe it would help someone.

My .gitignore:

# Disable all directories.
*/
!.gitignore

# Enable `Jenkins Service/init.groovy.d`.
!Jenkins Service/
Jenkins Service/*
!Jenkins Service/init.groovy.d/

# Enable `Scripts`.
!Scripts/

After git add .:

Changes to be committed:
  (use "git rm --cached <file>..." to unstage)
        new file:   .gitignore
        new file:   Jenkins Service/init.groovy.d/BuildRerunner.groovy
        new file:   Jenkins Service/init.groovy.d/rerun-last-prod-build.groovy
        new file:   Jenkins Service/init.groovy.d/rerun-zombie-builds.groovy
        new file:   Scripts/jenkins-delete-cache.bat

Thanks for the solution!
In my case git add * must be used after configuration of the gitignore file. Somehow git add . does not work.

Awesome, thanks!

In case it helps anyone else, this is what I needed for my case.

• Need to ignore everything at the root, including files and directories
• Except certain directories
• And certain subdirectories of those directories
• But ignore DS_Store in those directories

It didn't work to use ** or * to ignore everything and then unignore. it also didn't work to unignore subdirectories with their full relative path.

# ignore directories
*/
# ignore files at the root
/*

#----

# allow these
!.gitignore
!dir1
!dir2
!dir3
# .obsidian is subdir of the above dir1, dir2, dir3. but must be referenced like this
!.obsidian
# plugins is subdir of dir1/.obsidian, dir2/.obsidian, dir3/.obsidian
!plugins
# these are subdirs of .obsidian/plugins
!obsidian-vimrc-support
!file-diff

# but ignore these
*.DS_Store

After getting it right, all I needed was to run git status -u to check what it picked up.