Git Basics: Creating a Branch and Merging It

A branch is a movable name for a commit. It lets you develop a change separately, then bring that work into another branch when it is ready.

Run these commands in Bash with Git 2.28 or newer installed. Each article starts in a fresh temporary repository; no remote account is needed.

git_practice=$(mktemp -d) || exit
cd "$git_practice" || exit
git init -q -b main
git config user.name 'Practice User'
git config user.email 'practice@example.invalid'
git config commit.gpgsign false

These settings apply only to this repository; signing is disabled for the exercise. Use your own identity in real projects. The temporary files remain after the exercise.

Start from one commit

printf 'port=8080\n' > app.conf
git add app.conf
git commit -q -m 'Add application config'
git switch -q -c change-port
printf 'port=9090\n' > app.conf
git add app.conf
git commit -q -m 'Change application port'
git branch --show-current

change-port

git switch -c creates the branch and switches to it. The new commit moves change-port forward; main still points to the original commit.

Return to main

git switch -q main
cat app.conf

port=8080

Switching updates the working files to match the selected branch. Commit or otherwise preserve unfinished work before switching: local edits can carry across branches, or Git may refuse a switch that would overwrite them.

Merge the change

git merge -q --ff-only change-port
cat app.conf

port=9090

This succeeds because main has no separate commits since the branch was created. Git can move main straight forward to the same commit as change-port. This is a fast-forward and creates no merge commit.

--ff-only refuses the merge if the histories have diverged. If that happens in a real project, inspect both histories and choose the team’s merge or rebase workflow rather than forcing an update.

After checking the result, remove the merged local branch name:

git branch -d change-port

Git prints a deletion confirmation with a commit ID that varies. The commit remains reachable through main. None of these steps creates a pull request or updates a remote repository.

Reference

Git merge manual

Acknowledgements

This post was created with assistance from AI.