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Learn how to manage Git file history after `git mv` and merging branches. We explain how to recover lost file history and avoid common pitfalls.
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Understanding Git's mv and Merge: Does History Disappear?

In the world of version control, Git is a robust tool that offers numerous commands to manage your files efficiently. However, navigating file movements and merges can sometimes lead to confusion, especially when it comes to maintaining file history. One common dilemma among developers is whether moving a file (or folder) with git mv and subsequently merging that change can cause the loss of a file's commit history. In this post, we’ll unpack this problem and explore practical solutions to ensure your file history remains intact throughout these operations.

The Problem Scenario

Imagine you find yourself in the following situation:

Before Consolidation: Your main branch has a directory structure that includes various Python scripts organized into subdirectories.

After Consolidation: You reorganize your directories to better suit your project needs. For instance, you might move scripts into a different structure forever.

Here's how your project structure looks before and after consolidation:

Before Consolidation:

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

After Consolidation:

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

Feature Branch: You create a feature branch where you add a new file test4.py, which has a solid history of 10 commits.

After Merge: When you merge your feature branch back (using git merge -s ort), you notice that test4.py seems to have lost its history, or worse, it appears deleted.

Why Did This Happen?

If during the merge process, git mv led to your file being moved rather than deleted, you might not see the expected history reflected in your main branch. Git is designed to track moves, but if there were substantial changes or if the file was misaligned during the merge, you could end up in a situation where the history seems deleted or inaccessible.

Solutions to Recover File History

Fortunately, there are several approaches you can take to recover your file history and understand what happened during the merge. Below, we break these down into clear sections.

1. Use the gitk --follow Command

One of the simplest ways to trace the history of a moved or renamed file is to use the gitk command with the --follow option:

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

This command will show you the commit history of test4.py even if it has been moved to a different location.

2. Checking for Major Changes

If test4.py underwent significant alterations, you can enhance your tracking command with additional flags:

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

The -M50 option helps in tracking renames even when there’s been substantial changes in the file content.

3. Using git blame

If you want to find out who last modified the file, using the git blame command will automatically utilize the --follow parameter:

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

This will give you insights into the last modifications made to the file, along with the commit history.

4. Investigate Deleted Files

If the file appears deleted and you need to determine when it happened, try the following command to find the last commit that deleted it:

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

Append a caret symbol (^) to the commit hash that shows up, and this will give you the last known state of the file before it was deleted.

Conclusion

In conclusion, while moving files and merging branches can create confusion regarding commit history, understanding how Git tracks these movements is crucial for preserving your history. By leveraging commands like gitk, git blame, and various log options, you can recover and view your file his