How to generate and apply patches with git? — First published in fullweb.io issue #33

how-to-git-patch-diff.md

How to generate and apply patches with git?

It sometimes happen you need change code on a machine from which you cannot push to the repo. You’re ready to copy/paste what diff outputs to your local working copy.

You think there must be a better way to proceed and you’re right. It’s a simple 2 steps process:

1. Generate the patch:

git diff > some-changes.patch

2. Apply the diff:

Then copy this patch to your local machine, and apply it to your local working copy with:

git apply /path/to/some-changes.patch

And that’s it! The changes are now in your working copy and ready to be staged/commit/pushed :)

@h3ndry you can open your patch file in any text editor and can see changes and file informations.

Thanks for the snippets!
To make then work with changes to binary files, I had to run git diff --binary > some-changes.patch.

If you have a commit id, then you can also use

git show bc6626756 > ./my-changes.patch

and to restore use

git apply ./my-changes.patch

git diff will always add file path to the patch like this.

diff --git a/<file_path> b/<file_path>
...

If you want to reuse the same patch on the file that does not match this file_path, you can do it with patch command.

patch <file_to_patch> <file_with_patch>

I created patch file for stash using following command:
git stash show "stash@{0}" -p > '..\stashes\changes.patch'

When I try to apply the same using
git apply '..\stashes\changes.patch'

Got below error:
error: No valid patches in input (allow with "--allow-empty")

Path to the patch file is correct. Can someone please help?

If you run git diff it will show changes that were tracked previously. But newly added files are not shown in the diff. To create a patch, I did the following.

• git add -A # Add everything to the staging area.
• git diff --staged --patch > changes.patch # --staged shows all the changes including new files
• git reset # Reset to the old state

Now, I can apply the changes.

---

Edit: I just checked git diff --staged --patch and git diff --staged by creating two new patch files, and comparing them with the diff command. I don't find any difference.

@ssi-anik Didn't think about untracked files—I always forget about them when thinking about git command, thanks!

I believe you can simplify your solution even more by using intent-to-add like this:

git add --intent-to-add --all
# or
git add -NA

I can export the code change to .patch file, but the change only include the main part, Now I change the submodule and want to export the code change in submodule to the same .patch file so that I can apply the patch file for all code changes on new project including the submodule part, are there some commands to do this?

Hi

Git format-patch- 1- head

@MayuriVidekar, same error here on Windows. I'm pretty sure it used to work. Resorting now to git checkout -p the stash rev.

@MayuriVidekar @JulienCochuyt surely you're using PowerShell < 7.4. Upgrade or see https://stackoverflow.com/a/70283963/14098985 for workarounds.