Git patch LEARNOVITA

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

Last updated on 03rd Nov 2022, Artciles, Blog

About author

Ram Chandra (Git Technical Lead Engineer )

Ram Chandra is an Git Technical Lead Engineer and an expert in Hands-on experience in Git or GitHub ecosystem using Rust, Bash, Ruby, and REST APIs. He has a certified professional with more than 6 years of professional expertise.

(5.0) | 19847 Ratings 2150
    • 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.

Git patch

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,

  • 0001-Update-nf-again.patch
To create Git patch

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:

  • $ git format-patch -o <"new-feature-subdirectory"> <"commit">

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.

Are you looking training with Right Jobs?

Contact Us

Popular Courses