Introduction

There may be situations where you need to adjust the time of a Git commit. For example:

  • Organizing commit history across different time zones
  • Maintaining a chronological commit history of a project
  • Adjusting timestamps of restored code from a backup

However, adjusting commit times should be done with caution, especially in collaborative projects.

Methods to Adjust Commit Times

1. Specify Time When Creating a New Commit

When creating a new commit, you can specify a specific time:

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# Using ISO 8601 format
git commit --date="2024-05-25T23:31:13+09:00" -m "feat: Implement login feature"

# Specifying relative time
git commit --date="2 days ago" -m "docs: Update README"

2. Modify Time of Recent Commit

To modify the time of just the most recent commit:

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# Modifying time only
git commit --amend --date="2024-05-25T23:31:13+09:00" --no-edit

# Modifying both time and message
git commit --amend --date="2024-05-25T23:31:13+09:00" -m "Amended commit message"

3. Modify Time of Past Commits

To modify the time of a specific past commit, use interactive rebase:

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# Modify last 3 commits
git rebase -i HEAD~3

# Modify from a specific commit onwards
git rebase -i <commit-hash>

In the rebase editor:

edit abc1234 First commit message
pick def5678 Second commit message
pick ghi9012 Third commit message

Then:

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git commit --amend --date="2024-05-25T23:31:13+09:00" --no-edit
git rebase --continue

Practical Use Cases

Scenario 1: Syncing Offline Work

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# Commit your yesterday's work
git add .
git commit --date="yesterday 14:30" -m "feat: Offline work"

Scenario 2: Adjust for Time Zone Difference

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# Set commit time in UTC
git commit --date="2024-05-25T14:31:13Z" -m "docs: Update API specification"

Precautions

  1. Usage in Collaborative Projects

    • Avoid modifying time of already-pushed commits
    • Consult with teammates beforehand
    • Create a separate branch to work in

  2. Maintaining Git History

    • Modifying commit time changes history
    • May require force push
    • Backup is recommended

  3. Best Practices

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    # Backup current state before changes
git branch backup/before-rebase

# Force push if necessary after changes
git push origin master --force-with-lease

Conclusion

Adjusting commit times is a useful Git feature, but it should be used with caution. Especially in collaborative projects, consider team policies and Git workflow before using it.