How to See Who Changed a Line in Git Using git blame

Use the git blame command followed by the file name to see who last changed each line in that file. This command shows the author, commit hash, and timestamp for every line, helping you identify who changed a specific line.

Syntax

The basic syntax of git blame is:

• git blame [options] <file>: Shows the last change for each line in the specified file.
• Options can filter or format the output, like -L to limit lines or -e to show email addresses.

bash

git blame [options] <file>

Example

This example shows how to find who last changed each line in a file named app.js. It helps you identify the author and commit for every line.

bash

git blame app.js

Output

e3a1b2c4 (Alice 2024-06-01 14:22:10 +0200  1) const greet = () => {
5f7d9e8a (Bob   2024-06-02 09:15:30 +0200  2)   console.log('Hello, world!');
5f7d9e8a (Bob   2024-06-02 09:15:30 +0200  3) }

Common Pitfalls

Some common mistakes when using git blame include:

• Running git blame on a file that was recently renamed or moved without using the --follow option, which can miss history.
• Not limiting the output when the file is large, making it hard to find the line you want.
• Confusing git blame output with the current author if the line was changed multiple times.

To avoid these, use git blame --follow <file> to track history across renames and git blame -L <start,end> <file> to focus on specific lines.

bash

git blame --follow app.js

git blame -L 10,20 app.js

Quick Reference

Command	Description
git blame	Show last change info for each line in the file
git blame --follow	Include history across file renames
git blame -L	Show blame for specific line range
git blame -e	Show author email instead of name
git blame -C	Detect lines copied or moved within the file

Key Takeaways

Use git blame <file> to see who last changed each line in a file.

Add --follow to track changes through file renames.

Use -L option to limit output to specific lines.

Read the output carefully to understand author, commit, and timestamp per line.

Avoid confusion by combining blame with other git commands for full history.