Generally a patch – is a file containing source code differences. In a patch you can specify which line in which file should be added, updated or deleted. The structure of such file is standardized – that means if you create a patch file in Windows you can easily implement it on Linux.
Let’s imagine you have a project you work on. You have a production server and a development workstation. Before starting your work you copied the production source code to the workstation and initiated a Git repo there. After you finish updating you need to apply updates on the production server.
How can you do that? The easiest way is to create a patch.
Creating patches with Git
- Check out initial commit and create a version tag by command
git tag -a Initial_state
- Check out the commit with updated code. Create another version tag
git tag -a Problem_solved
- Verify tags are created
- Create a patch file
git diff Initial_state Problem_solved -- > the-patch.diff
- Move the-patch.diff file to the production server in the project root directory.
- Login to the production server via SSH and change directory to the project root directory.
- Open the-patch.diff file in text editor. You will see many instructions. The most important information for you is file names, e.g.
diff --git a/app/Console/Commands/someCommand.php b/app/Console/Commands/someCommand.php
- Create a backup of the current project state!
- Pay attention to the file path. Since you are in the project root directory, you need to cut off first parts of files paths: a/ and b/ while patch applying. To do that, use -p1 parameter of the patch command (-p1 stands for “cut 1 part of path”):
patch -p1 < ../the-patch.diff
- Carefully review the command’s output to avoid errors.