Default Behaviour Of "git push" Without A Branch Specified

When working with Git, understanding how Git push operates without specifying a branch can prevent many potential pitfalls in version control. This article will guide you through the default behaviour of Git Push Without A Branch Specified.

What is git push?

git push is a fundamental Git command used to upload local repository content to a remote repository. It transfers commits from your local branches to corresponding branches on the remote repository, providing collaboration among multiple developers.

Syntax:

git push <remote> <branch>

For example, pushing the current branch to the origin remote:

git push origin main

However, what happens if the branch is not specified?

Default Behavior Without a Branch Specified

When you execute git push without specifying a branch, the behavior depends on several factors:

1. Default Remote and Branch:

If you're on a branch that has an upstream branch set (the tracking branch is configured), Git pushes to that upstream branch. This is typical in many workflows where each local branch tracks a corresponding remote branch.

git push

In this case, Git pushes to the upstream branch defined for your current branch. If your local main branch tracks origin/main, running git push will push changes from main to origin/main.

2. Branch Not Configured:

If your current branch does not have an upstream branch set, Git will output an error indicating that the current branch lacks an upstream. For instance:

fatal: The current branch <branch-name> has no upstream branch.

3. Git Configuration:

The behavior can also be influenced by Git's configuration settings, especially push.default. This setting controls how Git selects which branches to push when no branch is explicitly specified.

Git push.default Settings

The push.default setting defines the behavior of git push without a specified branch. You can view or set this configuration using:

git config --global push.default <value>

Here's a rundown of the possible values for push.default:

1. simple: This is the default in Git 2.0 and later. It only pushes the current branch to its corresponding upstream branch if they have the same name. If they don’t, an error is raised.

git config --global push.default simple

2. matching: This setting pushes all local branches that have matching names in the remote repository. It was the default in Git versions earlier than 2.0.

git config --global push.default matching

3. upstream: Pushes the current branch to its upstream branch (configured with git branch --set-upstream-to or during branch creation). This is often used for maintaining a clear correspondence between local and remote branches.

git config --global push.default upstream

4. current: Pushes the current branch to a remote branch of the same name.

git config --global push.default current

5. nothing: Does not push anything. This can be useful if you want to prevent accidental pushes.

git config --global push.default nothing

Example

1. Using simple Mode

# Configuration
git config --global push.default simple

# Scenario
# You are on branch `main` which tracks `origin/main`

git push

This will push your main branch to origin/main. If main does not track origin/main, Git will raise an error.

2. Using matching Mode

# Configuration
git config --global push.default matching

# Scenario
# You have local branches `feature1` and `main` which both exist on the remote

git push

This will push both feature1 and main to their corresponding branches on the remote.

3. Using upstream Mode

# Configuration
git config --global push.default upstream

# Scenario
# You are on branch `develop` which tracks `origin/develop`

git push

This will push develop to origin/develop.