Split a subdirectory into a new Git repo

gistfile1.sh

# You need to install the command git-subtree from here:
# https://github.com/apenwarr/git-subtree

# Let's say you got a subdirectory 'lib-abc' under 'project' git repo that you like to
# split into a new repository

# First you need to create a bare repository, i.e. a Github project called 'lib-abc'
# Your new remote could be somethings like 'git@github.com:yourname/lib-abc.git'

cd project/
git subtree split --prefix=lib-abc -b new_branch

# add the lib-abc's remote at Github
git remote add split git@github.com:yourname/lib-abc.git

# push the splitted branch as a master to Github
git push split new_branch:master

# That's all :-)
# Now some clean up

git branch -D new_branch
git remote rm split