Moving Git repository content to another repository preserving history

Question

I think the commands you are looking for are:

cd repo2
git checkout master
git remote add r1remote **url-of-repo1**
git fetch r1remote
git merge r1remote/master --allow-unrelated-histories
git remote rm r1remote

After that repo2/master will contain everything from repo2/master and repo1/master, and will also have the history of both of them.

Perfectly described here https://www.smashingmagazine.com/2014/05/moving-git-repository-new-server/

First, we have to fetch all of the remote branches and tags from the existing repository to our local index:

git fetch origin

We can check for any missing branches that we need to create a local copy of:

git branch -a

Let’s use the SSH-cloned URL of our new repository to create a new remote in our existing local repository:

git remote add new-origin [email protected]:manakor/manascope.git

Now we are ready to push all local branches and tags to the new remote named new-origin:

git push --all new-origin 
git push --tags new-origin

Let’s make new-origin the default remote:

git remote rm origin

Rename new-origin to just origin, so that it becomes the default remote:

git remote rename new-origin origin

If you're looking to preserve the existing branches and commit history, here's one way that worked for me.

git clone --mirror https://github.com/account/repo.git cloned-repo
cd cloned-repo
git push --mirror {URL of new (empty) repo}

# at this point only remote cloned-repo is correct, local has auto-generated repo structure with folders such as "branches" or "refs"
cd ..
rm -rf cloned-repo
git clone {URL of new (empty) repo}
# only now will you see the expected user-generated contents in local cloned-repo folder

# note: all non-master branches are avaialable, but git branch will not show them until you git checkout each of them
# to automatically checkout all remote branches use this loop:
for b in `git branch -r | grep -v -- '->'`; do git branch --track ${b##origin/} $b; done

Now, suppose you want to keep the source and destination repos in sync for a period of time. For example, there's still activity within the current remote repo that you want to bring over to the new/replacement repo.

git clone -o old https://github.com/account/repo.git my-repo
cd my-repo
git remote add new {URL of new repo}

To pull down the latest updates (assuming you have no local changes):

git checkout {branch(es) of interest}
git pull old
git push --all new

NB: I have yet to use submodules, so I don't know what additional steps might be required if you have them.

Simplest approach if the code is already tracked by Git then set new repository as your "origin" to push to.

cd existing-project
git remote set-url origin https://clone-url.git
git push -u origin --all
git push origin --tags

This worked to move my local repo (including history) to my remote github.com repo. After creating the new empty repo at GitHub.com I use the URL in step three below and it works great.

git clone --mirror <url_of_old_repo>
cd <name_of_old_repo>
git remote add new-origin <url_of_new_repo>
git push new-origin --mirror

I found this at: https://gist.github.com/niksumeiko/8972566

Mirroring a repository

As per @Dan-Cohn answer Mirror-push is your friend here. This is my go to for migrating repos:

1．Open Git Bash.

2．Create a bare clone of the repository.

$ git clone --bare https://github.com/exampleuser/old-repository.git

3．Mirror-push to the new repository.

$ cd old-repository.git
$ git push --mirror https://github.com/exampleuser/new-repository.git

4．Remove the temporary local repository you created in step 1.

$ cd ..
$ rm -rf old-repository.git

Reference and Credit: https://help.github.com/en/articles/duplicating-a-repository