How to I combine two separate Git repositories?

Question

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:

   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.

• http://stackoverflow.com/questions/277029/combining-multiple-git-repositories
• http://stackoverflow.com/questions/1404232/create-a-git-repository-that-contains-another-git-repository

Answer 1

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"