How to view the change history of a file using Git

When using Git, viewing the change history of a file is a common and highly useful operation that helps us track and understand how the file has evolved over time. Specifically, you can achieve this through the following steps:

1. View the history using the git log command

First, you can use the git log command to view the commit history of the entire project. If you're interested in a specific file, you can specify the filename as a parameter to git log, which will show only the change history for that file. For example:

bash
git log -- path/to/file

This command lists all commits that affected the specified file, displaying the commit ID, author, date, and commit message for each.

2. View detailed changes for a specific commit

If you want to view the specific changes made to a file in a particular commit, you can use the git show command followed by the commit ID and file path. For example:

bash
git show COMMIT_ID -- path/to/file

This will display the detailed changes to the specified file in that commit, including which lines were added or deleted.

3. View a summary of the file's change history

For scenarios where you need a quick summary of the file's changes, you can use the git log command with the --patch or -p option, which not only shows the commit information but also the specific changes. The command is:

bash
git log -p -- path/to/file

Practical Application Example

In my previous work project, we needed to locate a long-standing bug that was introduced due to an incorrect change in a configuration file. By using:

bash
git log -p -- config/settings.py

I was able to review the historical changes to this file step by step and eventually identified the specific commit that caused the issue. After discussing with team members, we traced back the business requirements and code implementation at that time, confirmed the cause of the change, and developed a fix strategy.

Conclusion

Using Git to view the change history of a file not only helps us better understand the project's evolution but is also an important means for diagnosing issues, reviewing code, and reverting to previous states. In practical work, reasonably utilizing these commands can significantly improve our work efficiency and the maintainability of the project.