Find the REMOTE parent branch of a LOCAL git branch

Question

How do I get the name of the remote git branch from which the local git current commit was branched-off?

I assume this is a 4 step process, and that the first three steps might be as follows:

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Step One: Get the name of the current branch in the local git repo:

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git rev-parse --abbrev-ref HEAD    

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Step Two: Get the hash of the currently checked out commit from the local repo:

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git rev-parse HEAD          # full hash  

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Step Three: Get the name of the upstream tracking branch on the remote git repo:

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git rev-parse --abbrev-ref @{upstream}

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Step Four: Get the name of the parent upstream tracking branch on the remote git repo:

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What specific code is required to do this? After reading @ChrisJohnsen's answer to this other posting, I imagine that the solution involves looking for the most recent commit that was derived from another branch in the remote repository. However, the code in the answers to the linked posting all seem to be designed for local repositories. This current question is different because I am asking how to find the remote repository parent branch from a local repository child branch.

I am adding the bash tag because these commands are running on CentOS servers that can use bash scripting.

Answer 1

To get the remote parent branch by view all the branch structure, you can print the commit history as graph by any of below commands:

gitk --all
git log --oneline --decorate --graph --all

To get the remote parent branch only for a local branch by script, you can create local temp branches based on the remote branches. Then you can find the parent branch of the local branch from the temp branches. After finding the temp branch is the parent branch of the local branch, you can get the remote branch correspondingly. Finally, delete all the temp branches. Detail steps as below:

1. List all the remote branches by git branch -r (assume the remote branches are origin/master, origin/dev and origin/feature).

2. Get the tracking/remote branch from the local branch

   The way to get the remote branch of the given local branch as you use the commmand git rev-parse --abbrev-ref @{upstream} (assume it’s origin/master branch which you want to find it’s parent branch).

3. Create local temp branches from remote branches separately

   git branch -b origin-master origin/master        #Create a local branch origin-master from origin/master
   git branch -b origin-dev origin/dev
   git branach -b origin-feature origin/feature
   

4. Find the parent branch from the temp branches

   Now you just need to find origin-master branch’s parent branch from all the temp branches (origin-master, origin-dev and origin-feature). It converts to the same situation as the post (Find the parent branch of a Git branch) shows. And you can use the same way to achieve.

5. Convert the parent branch to the corresponding remote branch

   Such as you find the parent branch of origin-master branch is origin-dev, then replace - to / to get the remote parent branch name origin/dev.

6. Delete all the temp branches

   git branch -D origin-master
   git branch -D origin-dev
   git branch -D origin-feature