sebastiandaschner blog


Create Git patches from command line

friday, february 14, 2020

Git patches are an easy way to apply changes to a project if you don’t want to go through the regular commit-pull-request flow. Patches are files that contain an equivalent diff of a Git commit.

You can create a patch of your modified working state using git diff. The diff output is in the correct patch format.

$> git status
On branch master
Changes not staged for commit:
  (use "git add <file>..." to update what will be committed)
  (use "git checkout -- <file>..." to discard changes in working directory)
	modified:   hello.txt

no changes added to commit (use "git add" and/or "git commit -a")

$> git diff > ~/important-changes.patch

This will create a simple patch file that can be applied to a different repo and will create the same file changes in the working directory:

$> git status
On branch master
nothing to commit, working tree clean

$> git apply ~/important-changes.patch

$> git status
On branch master
Changes not staged for commit:
  [...]
	modified:   hello.txt

What’s also possible is to create a formatted patch from commits which includes the commit metadata. These patches were created to be sent via email.

You can use git format-patch <since> to create a patch from all commits since a certain point, or within a range, respectively.

$> git format-patch origin/master --output ~/
/home/sebastian/0001-changed-file.patch
/home/sebastian/0002-changed-file-again.patch

# or into a single file
$> git format-patch origin/master --stdout > ~/important-commits.patch

Again, these changes can be applied using git apply. Now, we can also use git am to apply all commits including their metadata:

$> git am ~/important-commits.patch
Applying: changed file
Applying: changed file again

These patches can be helpful for local workaround that you need to apply to codebases every now and then.

The content of this post was reposted from my newsletter issue 037.

 

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