It is highly recommended for QMK development, regardless of what is being done or where, to keep your master branch updated, but never commit to it. Instead, do all your changes in a development branch and issue pull requests from your branches when you're developing.
To reduce the chances of merge conflicts — instances where two or more users have edited the same part of a file concurrently — keep your master branch relatively up-to-date, and start any new developments by creating a new branch.
To keep your master branch updated, it is recommended to add the QMK Firmware repository ("repo") as a remote repository in git. To do this, open your Git command line interface and enter:
git remote add upstream https://github.com/qmk/qmk_firmware.git
?> The name upstream is arbitrary, but a common convention; you can give the QMK remote any name that suits you. Git's remote command uses the syntax git remote add <name> <url>, <name> being shorthand for the remote repo. This name can be used with many Git commands, including but not limited to fetch, pull and push, to specify the remote repo on which to act.
To verify that the repository has been added, run git remote -v, which should return the following:
$ git remote -v
origin https://github.com/<your_username>/qmk_firmware.git (fetch)
origin https://github.com/<your_username>/qmk_firmware.git (push)
upstream https://github.com/qmk/qmk_firmware.git (fetch)
upstream https://github.com/qmk/qmk_firmware.git (push)
Now that this is done, you can check for updates to the repo by running git fetch upstream. This retrieves the branches and tags — collectively referred to as "refs" — from the QMK repo, which now has the nickname upstream. We can now compare the data on our fork origin to that held by QMK.
To update your fork's master, run the following, hitting the Enter key after each line:
git checkout master
git fetch upstream
git pull upstream master
git push origin master
This switches you to your master branch, retrieves the refs from the QMK repo, downloads the current QMK master branch to your computer, and then uploads it to your fork.
To make changes, create a new branch by entering:
git checkout -b dev_branch
git push --set-upstream origin dev_branch
This creates a new branch named dev_branch, checks it out, and then saves the new branch to your fork. The --set-upstream argument tells git to use your fork and the dev_branch branch every time you use git push or git pull from this branch. It only needs to be used on the first push; after that, you can safely use git push or git pull, without the rest of the arguments.
?> With git push, you can use -u in place of --set-upstream — -u is an alias for --set-upstream.
You can name your branch nearly anything you want, though it is recommended to name it something related to the changes you are going to make.
By default git checkout -b will base your new branch on the branch that is currently checked out. You can base your new branch on an existing branch that is not checked out by adding the name of the existing branch to the command:
git checkout -b dev_branch master
Now that you have a development branch, open your text editor and make whatever changes you need to make. It is recommended to make many small commits to your branch; that way, any change that causes issues can be more easily traced and undone if needed. To make your changes, edit and save any files that need to be updated, add them to Git's staging area, and then commit them to your branch:
git add path/to/updated_file
git commit -m "My commit message."
git add adds files that have been changed to Git's staging area, which is Git's "loading zone." This contains the changes that are going to be committed by git commit, which saves the changes to the repo. Use descriptive commit messages so you can know what was changed at a glance.
?> If you've changed multiple files, you can use git add -- path/to/file1 path/to/file2 ... to add all your desired files.
The last step is to push your changes to your fork. To do this, enter git push. Git will then publish the current state of dev_branch to your fork.