In the realm of version control with Git, understanding the git diff command is crucial for developers. This post not only explores the basics but also dives into advanced uses of git diff, complete with detailed examples and code blocks for a comprehensive understanding.
Basic Usage of Git Diff
1. Viewing Uncommitted Changes
git diff
This command shows the differences between your working directory and the index (staging area). It’s helpful to review changes before staging them.
Example:
Suppose file.txt originally contains “Hello, World!” and you add “New line” to it. Running git diff will show:
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2. Viewing Changes That Are Staged for Commit
git diff --staged
This compares your staged changes with the last commit, useful for a final review before committing.
3. Comparing Two Files Within the Working Directory
git diff -- file1.txt file2.txt
This compares two local files, showing differences even if they aren’t tracked by Git.
Advanced Usage of Git Diff
1. Difference Between Two Branches
git diff main..feature-branch
This shows the changes between the main branch and feature-branch, useful for reviewing changes before merging branches.
Example:
Suppose in your main branch, you have a file hello.txt with “Hello, World!”, and in your feature-branch, it’s changed to “Hello, Git World!”. The command git diff main..feature-branch will show the differences.
2. Difference Between Two Commits
git diff <HASH-OLDER-COMMIT>..<HASH-NEWER-COMMIT>
This is for comparing specific commits, perhaps to understand the changes introduced in a feature branch.
3. Diff a File Across Branches or Commits
git diff main feature-branch file.txt
This focuses on how a single file (file.txt) differs between the main branch and feature-branch.
4. Diff a File Over Time in the Same Branch
First step: git log --before="2023-01-01" --after="2022-01-01" --follow -- file.txt
Then: git diff <old-commit-hash>..<new-commit-hash>
This combination is great for tracking a file’s evolution over a specified period.
5. Diff a File That Has Been Renamed
git diff <old-commit-hash>..<new-commit-hash>
Git automatically tracks renamed files post Git 2.9, making it easier to see changes to files even after renaming.
Advanced Features
Combining Diffs
git diff <commit1>..<commit2>..<commit3>
This aggregates changes from multiple commits into one view, simplifying code review or audits.
Diff with Context
git diff --unified=5 <commit1>..<commit2>
This shows more surrounding lines (context) around changes for better understanding.
Word Diff
git diff --word-diff <commit1>..<commit2>
It breaks down the differences to the word level, offering a more granular view.
Ignoring Space Changes
git diff -w <commit1>..<commit2>
This ignores white space changes, focusing only on actual content changes.
Wrapping it up 👏
Understanding git diff at both basic and advanced levels empowers developers to effectively track and understand changes in their codebase. Whether it’s a quick check of unstaged changes or a detailed comparison of branches, git diff proves to be an invaluable tool in the software development lifecycle. A deep dive into git diff not only enhances your Git proficiency but also contributes to better collaboration and code quality in your projects.
Cheers! 🍺