- Commit messages must have a subject line and may have body copy. These must be separated by a blank line.
- The subject line must not exceed 50 characters
- The subject line should be capitalized and must not end in a period
- The subject line must be written in imperative mood (Fix, not Fixed / Fixes etc.)
- The body copy must be wrapped at 72 columns
- The body copy must only contain explanations as to what and why, never how. The latter belongs in documentation and implementation.
This is an example of a complete commit message that adheres to this standard. Parts of this are optional, so read on.
Summarize changes in around 50 characters or less More detailed explanatory text, if necessary. Wrap it to about 72 characters or so. In some contexts, the first line is treated as the subject of the commit 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); various tools like `log`, `shortlog` and `rebase` can get confused if you run the two together. Explain the problem that this commit is solving. Focus on why you are making this change as opposed to how (the code explains that). Are there side effects or other unintuitive consequences of this change? Here's the place to explain them. Further paragraphs come after blank lines. - Bullet points are okay, too - Typically a hyphen or asterisk is used for the bullet, preceded by a single space, with blank lines in between, but conventions vary here If you use an issue tracker, put references to them at the bottom, like this: Resolves: #123 See also: #456, #789
Subject and Body
- A body copy is not required for commits that are overly simple. If you find yourself repeating the subject line in the body copy, it's a good sign that the body might be superfluous.
To perform a simple commit, a single command if sufficient:
$ git commit -m"Fix my subject line style"
If you need to write copy, issue
git commit. Git will now open your default text editor. To set a custom editor, use
git config --global core.editor nano (in this example, nano is the editor).
Here's an example of a subject and body commit message:
Derezz the master control program MCP turned out to be evil and had become intent on world domination. This commit throws Tron's disc into MCP (causing its deresolution) and turns it back into a chess game.
This makes browsing the git log easier:
$ git log commit 42e769bdf4894310333942ffc5a15151222a87be Author: Kevin Flynn <firstname.lastname@example.org> Date: Fri Jan 01 00:00:00 1982 -0200 Derezz the master control program MCP turned out to be evil and had become intent on world domination. This commit throws Tron's disc into MCP (causing its deresolution) and turns it back into a chess game.
You can view a shorter log, by restricting the output to the subject lines:
$ git log --oneline 42e769 Derezz the master control program
This provied an easy way to get a quick overview by means of reading the shortlog:
$ git shortlog Kevin Flynn (1): Derezz the master control program Alan Bradley (1): Introduce security program "Tron" Ed Dillinger (3): Rename chess program to "MCP" Modify chess program Upgrade chess program Walter Gibbs (1): Introduce protoype chess program
Use the Imperative
Inkeeping with the standard output of git itself, all commit subject lines must be written using the imperative:
- Refactor subsystem X for readability
- Update getting started documentation
- Remove deprecated methods
- Release version 1.0.0
- Fixed bug with Y
- Changing behavior of X
- More fixes for broken stuff
- Sweet new API methods
Your commit subject line must be able to complete the sentence
If applied, this commit will ...
If it doesn't, it's non-conformant. The body may use any style you want.
Use the Body to Explain the Background and Reasoning, not the Implementation
Especially if the diff is rather large or extremely clustered, you can save all fellow developers some time by explaining why you did what.
Here's a perfect example:
commit eb0b56b19017ab5c16c745e6da39c53126924ed6 Author: Pieter Wuille <email@example.com> Date: Fri Aug 1 22:57:55 2014 +0200 Simplify serialize.h's exception handling Remove the 'state' and 'exceptmask' from serialize.h's stream implementations, as well as related methods. As exceptmask always included 'failbit', and setstate was always called with bits = failbit, all it did was immediately raise an exception. Get rid of those variables, and replace the setstate with direct exception throwing (which also removes some dead code). As a result, good() is never reached after a failure (there are only 2 calls, one of which is in tests), and can just be replaced by !eof(). fail(), clear(n) and exceptions() are just never called. Delete them.
This is way easier to parse than the corresponding diff.
Subject Line Standard Terminology
|Add||Create a capability e.g. feature, test, dependency.|
|Cut||Remove a capability e.g. feature, test, dependency.|
|Fix||Fix an issue e.g. bug, typo, accident, misstatement.|
|Bump||Increase the version of something e.g. dependency.|
|Make||Change the build process, or tooling, or infra.|
|Start||Begin doing something; e.g. create a feature flag.|
|Stop||End doing something; e.g. remove a feature flag.|
|Refactor||A code change that MUST be just a refactoring.|
|Reformat||Refactor of formatting, e.g. omit whitespace.|
|Optimize||Refactor of performance, e.g. speed up code.|
|Document||Refactor of documentation, e.g. help files.|
Subject lines must never contain (and / or start with) anything else. Especially not something that's unique to your system, like
- [bug] ...
- (release) ...
- #12345 ...
- docs: ...