Simple Git Tutorial: Branching and Merging

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Git's powerful branching and merging capabilities can help you deal with parallel collaborative development processes. Let's take a look.

So far, we've been working on a single default branch created by Git. The name of this branch is main. (It used to be master. See github/renaming: Guidance for changing the default branch name for GitHub repositories) Our every commit becomes a new node on this branch.

When we want to add a new feature, but aren't sure if the new feature is good enough to use, the natural thought is that we want to branch out based on our current location and do our new feature development and experimentation on the new branch. If it's good, merge it into the main branch. Otherwise discard it.

Branching

The basic commands for working on local branches are listed below:

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# lists all the local branches
git branch

# creates a new local branch named <branch_name>
git branch <branch_name>

# checks out branch <branch_name>
git checkout <branch_name>

# combines the create and check-out commands into one:
git checkout -b <branch_name>

# shows the latest commits of every branch
git branch -v

# renames a local branch
git branch -m <new_branch_name>
git branch -m <old_branch_name> <new_branch_name>

# deletes a local branch
git branch -d <branch_name>
git branch -D <branch_name>  # force

All of the above commands work on the local branch(es). Then let's take a look at the remote branch(es).

To list all the local and remote branches, run:

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git branch --all
# or
git branch -a

When you clone a repo from the Internet, you may find that there is a main branch and an origin/main branch. Here, main is a local branch, and origin/main is a remote branch (where origin means a remote server called origin and main means a branch of the same name on that remote server).

In this case, the local branch main and the remote branch origin/main are related in some way, called tracking. The local branch is called the tracking branch. The corresponding branch on the remote server is called the upstream branch. Usually, the tracking branch shares a name with its upstream branch (e.g., the upstream branch of a local branch feature is origin/feature), but that's not a requirement.

For example, the commands below create a new local branch feature and its upstream branch origin/feature:

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git checkout -b feature
git push -u origin feature  # or `git push --set-upstream origin feature`

Run the command below to show the connection:

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git branch -vv

More commands may be helpful:

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# sets up a new tracking
git checkout --track <server_name>/<branch>
# or
git checkout -b <branch>
git branch -u <server_name>/<branch>

# stops tracking
git brach --unset-upstream <branch>

# deletes a remote branch
git push origin --delete <branch_name>

Commands to rename a remote branch

There is no direct command to rename a remote branch. But you can do it like this:

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git pull origin <old_branch_name>
git push origin --delete <old_branch_name>
git branch -m <old_branch_name> <new_branch_name>
git push -u origin <new_branch_name>

Merging

To merge the other branch to this one, run:

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git merge <branch_name>

If your current branch is master, this command merge <branch_name> to master.

To show all the branches that have/haven't been merged to this branch, run:

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git branch --merged
git branch --no-merged

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