How can one change the timestamp of an old commit

Question

The answers to How to modify existing, unpushed commits? describe a way to amend previous commit messages that haven't yet been pushed upstream. The new messages inherit the timestamps of the original commits. This seems logical, but is there a way to also re-set the times?

Answer 1

if it is previous last commit.

git rebase  -i HEAD~2
git commit --amend --date=now

if you already push to orgin and can force use:

git push --force 

if you can't force the push and if it is pushed, you can't change the commit! .

Answer 2

If you want to perform the accepted answer (https://stackoverflow.com/a/454750/72809) in standard Windows command line, you need the following command:

git filter-branch -f --env-filter "if [ $GIT_COMMIT = 578e6a450ff5318981367fe1f6f2390ce60ee045 ]; then export GIT_AUTHOR_DATE='2009-10-16T16:00+03:00'; export GIT_COMMITTER_DATE=$GIT_AUTHOR_DATE; fi"

Notes:

• It may be possible to split the command over multiple lines (Windows supports line splitting with the carret symbol ^), but I didn't succeed.
• You can write ISO dates, saving a lot of time finding the right day-of-week and general frustration over the order of elements.
• If you want the Author and Committer date to be the same, you can just reference the previously set variable.

Many thanks go to a blog post by Colin Svingen. Even though his code didn't work for me, it helped me find the correct solution.

Answer 3

git commit --amend --date="now"

Answer 4

I created this npm package to change date of old commits.

https://github.com/bitriddler/git-change-date

Sample Usage:

npm install -g git-change-date
cd [your-directory]
git-change-date

You will be prompted to choose the commit you want to modify then to enter the new date.

If you want to change a commit by specific hash run this git-change-date --hash=[hash]

Answer 5

There are already many great answers, but when I want to change date for multiple commits in one day or in one month, I don't find a proper answer. So I create a new script for this with explaintion, hope it will help someone:

#!/bin/bash

# change GIT_AUTHOR_DATE for commit at Thu Sep 14 13:39:41 2017 +0800
# you can change the data_match to change all commits at any date, one day or one month
# you can also do the same for GIT_COMMITTER_DATE

git filter-branch --force --env-filter '

date_match="^Thu, 14 Sep 2017 13+"              

# GIT_AUTHOR_DATE will be @1505367581 +0800, Git internal format 
author_data=$GIT_AUTHOR_DATE;                   
author_data=${author_data#@}                  
author_data=${author_data% +0800}                # author_data is 1505367581     

oneday=$((24*60*60))

# author_data_str will be "Thu, 14 Sep 2017 13:39:41 +0800", RFC2822 format
author_data_str=`date -R -d @$author_data`      

if [[ $author_data_str =~ $date_match ]];
then
    # remove one day from author_data
    new_data_sec=$(($author_data-$oneday))
    # change to git internal format based on new_data_sec
    new_data="@$new_data_sec +0800"             
    export GIT_AUTHOR_DATE="$new_data"
fi
' --tag-name-filter cat -- --branches --tags

The date will be changed:

AuthorDate: Wed Sep 13 13:39:41 2017 +0800