Скачать или смотреть How to Efficiently Extract a Single Line of Modifications with git diff

Learn how to use Bash and `git diff` to retrieve the exact line you modified in your files. This guide provides a clear step-by-step solution for Jenkins users.
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This video is based on the question https://stackoverflow.com/q/72047153/ asked by the user 'paul' ( https://stackoverflow.com/u/854207/ ) and on the answer https://stackoverflow.com/a/72048796/ provided by the user 'jthill' ( https://stackoverflow.com/u/1290731/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Extracting Modifications in Git with a One-Liner

When working with git, particularly in a Jenkins environment, you may want to see exactly what changes you've made in a file. While the git diff command provides a comprehensive overview of modifications, you might find yourself in need of a more streamlined approach. In this guide, we'll dissect a solution to extract your most recent single-line modification effectively utilizing Bash and git diff.

The Problem

In a Jenkins DSL script, you may want a command that succinctly returns just the modified text from a file. The challenge previously tackled was getting a summary of changes, like this output:

[[See Video to Reveal this Text or Code Snippet]]

However, the goal here is to specifically extract the text that was added or modified—such as "hello world." Let’s explore how to achieve that.

The Solution

The solution comes down to using a combination of git diff and sed commands. Here’s the streamlined command you'll want to use:

[[See Video to Reveal this Text or Code Snippet]]

Breaking Down the Command

git diff -U0: The -U0 option modifies the output of git diff, limiting the context lines around the change to zero. This means you'll only see the lines that have actually changed, without surrounding lines that may be part of the file.

sed 1,/^@@/d: This sed command works as follows:

1,/^@@/: This tells sed to match from the first line to the line containing @@, which is generally where the change summary appears in git diff output.

d: Deletes that matched range from the output. As a result, you’re left with just the modified lines.

Stripping the Leading Character

The command above might still include leading indicators such as a +, indicating added lines. To tidy up the output even further, you can incorporate an additional sed command to remove leading characters. An example enhancement could be:

[[See Video to Reveal this Text or Code Snippet]]

This final output will yield clean text reflecting only the changes you made, like "hello world."

Summary

Using a combination of git diff and sed, you can efficiently extract modifications from your projects in Jenkins. This method is not only effective but also clean and quick, allowing you to see your changes at a glance. Whether you're troubleshooting code or simply keeping track of your latest contributions, mastering this one-liner will streamline your workflow significantly.

Make sure to try this command in your environment to see how effortlessly you can extract modifications directly from Git!