git-examples.txt

Here's a scenario where you (user1) have a git repo on github (repo1),
and want to merge your code into another git repo (repo2) that belongs
to another person (user2). I'm assuming we're going to do this on/via
github (GH) but procedures on other cloud services should match
closely.

We use the concept called "a pull request from a branch", unless user2
has given you direct access to their repo2 of course.  The procedure
below allows you to bypass this special access and prepare your own
cloned version of repo2 with your repo1 code.

As far as I know, you cannot retain the history of your repo1 into
repo2, but pending a final word on that, here is the procedure to
merge user1/repo1 into user2/repo2:

1. Fork the other repo (user2/repo2) into your GH (as user1/repo2) space.
   This is easiest done on github.com, though there are command line
   versions of this as well.  (this would cover steps 1-2)

2. Clone the repo (repo2) from your GH space to your laptop
          git clone https:/github.com/user1/repo2
	  cd repo2

3. Create a branch (branch1) and switch to it
   	  git branch branch1
	  git checkout branch1

4. Copy the files you want to merge from your local copy in repo1 into
   this repo2, add them, and commit them. then push it back to GH
   	  cp -i ../repo1/file1 .
	  git add file1
	  git commit file1
	  git push -u origin branch1
   (this push needs a first time syntax change, since that branch
    does not exist yet in your GH's repo2; after this it's just "git push")

5. Now go on your GH's repo2 and change to this branch and issue a pull request
   from this branch to the upstream (user2)
   We normally call your own GH repo2 the "origin", and will designate the
   parent repo2 as the "upstream", so we can later merge new contributions
   made to upstreams repo2 into ours. See next and final step.

6. On your laptop you can find out your remotes with
      	  git remote
   and add this new "upstream" remote using
          git add remote upstream https://github.com/name2/repo2
   The commands
          git checkout master
          git fetch upstream
	  git merge upstream/master
   will now merge the upstream master into your master, so you are back in
   sync.  You normally only do this after user1 has followed up on your
   pull request, so your branch1 code is back on the upstream/master.
   Your branch could then be discarded, or you can later continue to work
   on it for pull requests back to the upstream.  If you continue with branch1,
   make sure that branch is in sync with your master, otherwise your pull request
   is going to look very strange.

7. Optionally, on your branch you could merge in the changes that are now on
   your master. This way you can next time continue to call pull requests
   from this branch. Or delete the branch and use a new branch. Up to you.

          git checkout branch1
	  git merge master
	  
   

NOTE added:
   Several pages describe how to merge two repos, and not loose file history.
   https://saintgimp.org/2013/01/22/merging-two-git-repositories-into-one-repository-without-losing-file-history/
   https://stackoverflow.com/questions/1425892/how-do-you-merge-two-git-repositories