An Overview of Patch Workflows | Benefits and Special Features [ For Freshers and Experience ]

• In this article you will get
• 1.What is a Git patch?
• 2.What is git format-patch?
• 3.How to create a Git patch?
• 4.What does format-patch do?
• 5.What is the format of a Git patch?
• 6.When should I format a git patch?
• 7.Git format-patch HEAD
• 8.Conclusion

What is Git patch?

A patch in Git is the textual representation of changes in a commit, formatted in a way that a Git can reconstruct a commit and apply it on a branch in the another repository.

What is a git format-patch?

Git format-patch is Git command that automatically generates a patches between each commit and it’s parent, for a given set of a commits. These patches are formatted such that they can simply be a shared over an email, so that are recipient can apply those commits to own repository.

How to create Git patch?

Creating a patch is the simple as running git format-patch <"commit"> in a local Git repo.

Can specify a commit using it’s commit id, any branch or tag name, or variation of Git HEAD such as HEAD^ for a previous commit.

After running command, see one or more .patch files generated in a current directory containing patch data. The file names are prefixed with a 4-digit number indicating their order in a patch series, followed by hyphen-separated string created using commit message. For the format used above,

What does a format-patch do?

By default, running git format-patch will create a patch for each commit starting with a specified commit, and ending with currently checked-out commit.One patch is generated per commit based on a diff between the each commit and its parent.

Git format-patch example:

Can format Git patches for a one commit at a time, or for the multiple commits at once. start with the formatting patches for multiple commits since that is more common scenario.

Git-Format Patch Multiple Commits:

By default, when run the standard git format-patch <"commit">, a patch will be created for an each commit starting at one can specified with <"commit">, up until a current HEAD is reached. Therefore, usually end up with the more than 1 patch being created, unless start generating at HEAD^ (aka HEAD~1), which isa commit previous to currently checked out HEAD. This means no patches will be created for a commits previous to a <"commit"> that can specified.

Alternatively, can use a –root flag to instead create the patches for all commits from the beginning or commit history, up until the specified <"commit">.

What is a format of a Git patch?

A sample format for an email patch in Git. Let’s expand on that. can think of each patch file as being message – and it really is since it’s meant to be emailed as the message to another dev.

This message starts with the email header that includes a “From:”, “Date:”, and “Subject:” fields. Note that subject field contains a first line from commit message of a corresponding commit.

Next comes remaining lines (if there are any) of a commit message. Our example format above does not include the more lines in the commit a log message.

After this, there is 3-hyphen delimiter, separating a commit message from patch content itself.Lastly, have the actual diffstat output, which represents a meat of the patch. This is actually output of the diff -p –stat command.

When should format a git patch?

Should format a patch in a Git any time want to send one or more commits to another person by a email. This could simply be to get their input or review on a proposed code changes.

It could also be to share the commit with the project maintainer for them to integrate into their own branch.

How can see a git patch?

Can see the patch files in a current directory by running a ls command in Linux or MacOS. In Windows can use a dir command. Alternatively, can see the patches listed in a file explorer in any operating system.Keep in mind that if generating a long patch series with more patches, and may want to put them in their own subdirectory using a -o option:

The specified subdirectory will be created if it doesn’t yet be exist.This can be useful for a grouping together patches related to a particular feature, so can make sure to only mail out those patches together and no others by an accident.

How do view a patch file?

Since Git patches are just text files with the .patch extension, and can view them with the any text editor. This could be command-line text editor like Vim or a favorite GUI editor.

Git format-patch HEAD

If try to run a git format-patch on its own or git format-patch HEAD, won’t get any output and no patch will be created. That’s because there are no differences between a specified patch (HEAD) and a current commit (which is also be a HEAD). So confused by this, just realize need to specify the commit earlier on in a branch history.

Conclusion

In this article, explained the purpose of Git’s format patch command and explained how it works.To format a Git patch and when to do so. saw that a patch in Git is just the textual representation of diff between a commit and its parent. These diffs are formatted in the standardized way that makes them convenient to send an over email.