How to I combine two separate Git repositories?

I have cloned a git repo which has my emacs config files in. I would like to add pylookup in a subdirectory. What is the correct way to do this?

Below are the options I can think of.

1. If I clone it into ~/.emacs.d/pylookup/ and add that folder to my emacs repo, will that update properly when I do开发者_Python百科:

   cd ~/.emacs.d/pylookup/
   git pull
   cd ~/.emacs.d
   git commit -a -m "updates to pylookup"
   git push
   

   i.e. when I pull those changes on my other machines will I have the new version of pylookup?

2. Do I simply get my emacs repo to ignore pylookup/* and update it on every machine whenever pylookup is updated. This would get annoying if there was a few repo's and a few machines but I can live with it.

3. Is there some smart tricks with git submodule. If so could you provide an explanation I didn't really understand the documentation. How would I pull changes for emacs and for pylookup.

4. Do I go with answer 2 but make a script to update all sub-repos. If I did that I could run that once on each machine every time pylookup changed.

Couple of possible related posts.

• Combining multiple git repositories
• Create a git repository that contains another git repository

If you create a Git submodule:

$ git submodule add git://github.com/tsgates/pylookup.git pylookup
$ git submodule init pylookup
$ git submodule update pylookup

Let's say there are some changes to pylookup and you want to get them:

$ cd pylookup
$ git pull origin master
$ cd ..
$ git add pylookup
$ git commit -m "Track new commit of pylookup"

I used subtree merge with a similar problem - http://git-scm.com/book/en/Git-Tools-Subtree-Merging. Something like:

$ git remote add -f pylookup /path/to/pylookup
$ git merge -s ours --no-commit pylookup/master
$ git read-tree --prefix=pylookup/ -u pylookup/master
$ git ci -m "merging pylookup into pylookup subdirectory"

Good guide here: http://jasonkarns.com/blog/merge-two-git-repositories-into-one