# Git Style Guide This is a Git Style Guide inspired by [*How to Get Your Change Into the Linux Kernel*](https://kernel.org/doc/html/latest/process/submitting-patches.html), the [git man pages](http://git-scm.com/doc) and various practices popular among the community. Translations are available in the following languages: * [Chinese (Simplified)](https://github.com/aseaday/git-style-guide) * [Chinese (Traditional)](https://github.com/JuanitoFatas/git-style-guide) * [French](https://github.com/pierreroth64/git-style-guide) * [Georgian](https://github.com/davidkadaria/git-style-guide) * [German](https://github.com/runjak/git-style-guide) * [Greek](https://github.com/grigoria/git-style-guide) * [Italian](https://github.com/vincendep/git-style-guide) * [Japanese](https://github.com/objectx/git-style-guide) * [Korean](https://github.com/ikaruce/git-style-guide) * [Polish](https://github.com/mbiesiad/git-style-guide/tree/pl_PL) * [Portuguese](https://github.com/guylhermetabosa/git-style-guide) * [Russian](https://github.com/alik0211/git-style-guide) * [Spanish](https://github.com/jeko2000/git-style-guide) * [Thai](https://github.com/zondezatera/git-style-guide) * [Turkish](https://github.com/CnytSntrk/git-style-guide) * [Ukrainian](https://github.com/denysdovhan/git-style-guide) If you feel like contributing, please do so! Fork the project and open a pull request. # Table of contents 1. [Branches](#branches) 2. [Commits](#commits) 1. [Messages](#messages) 3. [Merging](#merging) 4. [Misc.](#misc) ## Branches * Choose *short* and *descriptive* names: ```shell # good $ git checkout -b oauth-migration # bad - too vague $ git checkout -b login_fix ``` * Identifiers from corresponding tickets in an external service (eg. a GitHub issue) are also good candidates for use in branch names. For example: ```shell # GitHub issue #15 $ git checkout -b issue-15 ``` * Use lowercase in branch names. External ticket identifiers with uppercase letters are a valid exception. Use *hyphens* to separate words. ```shell $ git checkout -b new-feature # good $ git checkout -b T321-new-feature # good (Phabricator task id) $ git checkout -b New_Feature # bad ``` * When several people are working on the *same* feature, it might be convenient to have *personal* feature branches and a *team-wide* feature branch. Use the following naming convention: ```shell $ git checkout -b feature-a/main # team-wide branch $ git checkout -b feature-a/maria # Maria's personal branch $ git checkout -b feature-a/nick # Nick's personal branch ``` Merge at will the personal branches to the team-wide branch (see ["Merging"](#merging)). Eventually, the team-wide branch will be merged to "main". * Delete your branch from the upstream repository after it's merged, unless there is a specific reason not to. Tip: Use the following command while being on "main", to list merged branches: ```shell $ git branch --merged | grep -v "\*" ``` ## Commits * Each commit should be a single *logical change*. Don't make several *logical changes* in one commit. For example, if a patch fixes a bug and optimizes the performance of a feature, split it into two separate commits. *Tip: Use `git add -p` to interactively stage specific portions of the modified files.* * Don't split a single *logical change* into several commits. For example, the implementation of a feature and the corresponding tests should be in the same commit. * Commit *early* and *often*. Small, self-contained commits are easier to understand and revert when something goes wrong. * Commits should be ordered *logically*. For example, if *commit X* depends on changes done in *commit Y*, then *commit Y* should come before *commit X*. Note: While working alone on a local branch that *has not yet been pushed*, it's fine to use commits as temporary snapshots of your work. However, it still holds true that you should apply all of the above *before* pushing it. ### Messages * Use the editor, not the terminal, when writing a commit message: ```shell # good $ git commit # bad $ git commit -m "Quick fix" ``` Committing from the terminal encourages a mindset of having to fit everything in a single line which usually results in non-informative, ambiguous commit messages. * The summary line (ie. the first line of the message) should be *descriptive* yet *succinct*. Ideally, it should be no longer than *50 characters*. It should be capitalized and written in imperative present tense. It should not end with a period since it is effectively the commit *title*: ```shell # good - imperative present tense, capitalized, fewer than 50 characters Mark huge records as obsolete when clearing hinting faults # bad fixed ActiveModel::Errors deprecation messages failing when AR was used outside of Rails. ``` * After that should come a blank line followed by a more thorough description. It should be wrapped to *72 characters* and explain *why* the change is needed, *how* it addresses the issue and what *side-effects* it might have. It should also provide any pointers to related resources (eg. link to the corresponding issue in a bug tracker): ```text Short (50 chars or fewer) summary of changes More detailed explanatory text, if necessary. Wrap it to 72 characters. In some contexts, the first line is treated as the subject of an email and the rest of the text as the body. The blank line separating the summary from the body is critical (unless you omit the body entirely); tools like rebase can get confused if you run the two together. Further paragraphs come after blank lines. - Bullet points are okay, too - Use a hyphen or an asterisk for the bullet, followed by a single space, with blank lines in between The pointers to your related resources can serve as a footer for your commit message. Here is an example that is referencing issues in a bug tracker: Resolves: #56, #78 See also: #12, #34 Source: http://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html ``` Ultimately, when writing a commit message, think about what you would need to know if you run across the commit in a year from now. * If a *commit A* depends on *commit B*, the dependency should be stated in the message of *commit A*. Use the SHA1 when referring to commits. Similarly, if *commit A* solves a bug introduced by *commit B*, it should also be stated in the message of *commit A*. * If a commit is going to be squashed to another commit use the `--squash` and `--fixup` flags respectively, in order to make the intention clear: ```shell $ git commit --squash f387cab2 ``` *(Tip: Use the `--autosquash` flag when rebasing. The marked commits will be squashed automatically.)* ## Merging * **Do not rewrite published history.** The repository's history is valuable in its own right and it is very important to be able to tell *what actually happened*. Altering published history is a common source of problems for anyone working on the project. * However, there are cases where rewriting history is legitimate. These are when: * You are the only one working on the branch and it is not being reviewed. * You want to tidy up your branch (eg. squash commits) and/or rebase it onto the "main" in order to merge it later. That said, *never rewrite the history of the "main" branch* or any other special branches (ie. used by production or CI servers). * Keep the history *clean* and *simple*. *Just before you merge* your branch: 1. Make sure it conforms to the style guide and perform any needed actions if it doesn't (squash/reorder commits, reword messages etc.) 2. Rebase it onto the branch it's going to be merged to: ```shell [my-branch] $ git fetch [my-branch] $ git rebase origin/main # then merge ``` This results in a branch that can be applied directly to the end of the "main" branch and results in a very simple history. *(Note: This strategy is better suited for projects with short-running branches. Otherwise it might be better to occassionally merge the "main" branch instead of rebasing onto it.)* * If your branch includes more than one commit, do not merge with a fast-forward: ```shell # good - ensures that a merge commit is created $ git merge --no-ff my-branch # bad $ git merge my-branch ``` ## Misc. * There are various workflows and each one has its strengths and weaknesses. Whether a workflow fits your case, depends on the team, the project and your development procedures. That said, it is important to actually *choose* a workflow and stick with it. * *Be consistent.* This is related to the workflow but also expands to things like commit messages, branch names and tags. Having a consistent style throughout the repository makes it easy to understand what is going on by looking at the log, a commit message etc. * *Test before you push.* Do not push half-done work. * Use [annotated tags](https://git-scm.com/book/en/v2/Git-Basics-Tagging#_annotated_tags) for marking releases or other important points in the history. Prefer [lightweight tags](https://git-scm.com/book/en/v2/Git-Basics-Tagging#_lightweight_tags) for personal use, such as to bookmark commits for future reference. * Keep your repositories at a good shape by performing maintenance tasks occasionally: * [`git-gc(1)`](http://git-scm.com/docs/git-gc) * [`git-prune(1)`](http://git-scm.com/docs/git-prune) * [`git-fsck(1)`](http://git-scm.com/docs/git-fsck) # License ![cc license](http://i.creativecommons.org/l/by/4.0/88x31.png) This work is licensed under a [Creative Commons Attribution 4.0 International license](https://creativecommons.org/licenses/by/4.0/). # Credits Agis Anastasopoulos / [@agisanast](https://twitter.com/agisanast) / http://agis.io ... and [contributors](https://github.com/agis-/git-style-guide/graphs/contributors)!