# Create and switch to a new branch based off the master branch in Nixpkgs
   git switch --create update-hello upstream/master
   ```

   To avoid having to download and build potentially many derivations, at the expense of using a potentially outdated version, you can base the branch off a specific [Git commit](https://www.git-scm.com/docs/gitglossary#def_commit) instead:
   - The commit of the latest `nixpkgs-unstable` channel, available [here](https://channels.nixos.org/nixpkgs-unstable/git-revision).
   - The commit of a local Nixpkgs downloaded using [nix-channel](https://nixos.org/manual/nix/stable/command-ref/nix-channel), available using `nix-instantiate --eval --expr '(import <nixpkgs/lib>).trivial.revisionWithDefault null'`
   - If you're using NixOS, the commit of your NixOS installation, available with `nixos-version --revision`.

   Once you have an appropriate commit you can use it instead of `upstream/master` in the above command:
   ```bash
   git switch --create update-hello <the desired base commit>
   ```

3. Make the desired changes in the local Nixpkgs repository using an editor of your choice.
   Make sure to:
   - Adhere to both the [general code conventions][code-conventions], and the code conventions specific to the part you're making changes to.
     See the [overview section][overview] for more specific information.
   - Test the changes.
     See the [overview section][overview] for more specific information.
   - If necessary, document the change.
     See the [overview section][overview] for more specific information.

4. Commit your changes using `git commit`.
   Make sure to adhere to the [commit conventions](#commit-conventions).

   Repeat the steps 3-4 as many times as necessary.
   Advance to the next step if all the commits (viewable with `git log`) make sense together.

5. Push your commits to your fork of Nixpkgs.
   ```
   git push --set-upstream origin HEAD
   ```

   The above command will output a link that allows you to directly quickly do the next step:
   ```
   remote: Create a pull request for 'update-hello' on GitHub by visiting:
   remote:      https://github.com/myUser/nixpkgs/pull/new/update-hello
   ```

6. [Create a pull request](https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/proposing-changes-to-your-work-with-pull-requests/creating-a-pull-request#creating-the-pull-request) from the new branch in your Nixpkgs fork to the upstream Nixpkgs repository.
   Use the branch from step 2 as the pull requests base branch.
   Go through the [pull request template](#pull-request-template) in the pre-filled default description.

7. Respond to review comments, potential CI failures and potential merge conflicts by updating the pull request.
   Always keep the pull request in a mergeable state.

   This process is covered in more detail from the non-technical side in [I opened a PR, how do I get it merged?](#i-opened-a-pr-how-do-i-get-it-merged).

   The custom [OfBorg](https://github.com/NixOS/ofborg) CI system will perform various checks to help ensure code quality, whose results you can see at the bottom of the pull request.
   See [the OfBorg Readme](https://github.com/NixOS/ofborg#readme) for more details.

   - To add new commits, repeat steps 3-4 and push the result using
     ```
     git push
     ```

   - To change existing commits you will have to [rewrite Git history](https://git-scm.com/book/en/v2/Git-Tools-Rewriting-History).
     Useful Git commands that can help a lot with this are `git commit --patch --amend` and `git rebase --interactive`.
     With a rewritten history you need to force-push the commits using
     ```
     git push --force-with-lease
     ```

   - In case of merge conflicts you will also have to [rebase the branch](https://git-scm.com/book/en/v2/Git-Branching-Rebasing) on top of current `master`.
     Sometimes this can be done [on GitHub directly](https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/proposing-changes-to-your-work-with-pull-requests/keeping-your-pull-request-in-sync-with-the-base-branch#updating-your-pull-request-branch), but if not you will have to rebase locally using