date change of commit?

Hello,

Is it possible to change the date of a commit?

Thank you,

Alex

Alex K <spaceoutlet@gmail.com> writes:

See git-filter-branch. This won't change the date of the existing commit (which is impossible in Git), but will create another commit where only the date has been changed.

Thank you. And how would you use git-filter-branch to create another branch with a different time stamp? Is it possible to commit under a different time stamp than the one provided by your default local time?

2009/10/25 Matthieu Moy <Matthieu.Moy@grenoble-inp.fr>:

On Tue, Oct 27, 2009 at 10:41:47AM +0100, Alex K <spaceoutlet@gmail.com> wrote:

You can set GIT_AUTHOR_DATE and GIT_COMMITTER_DATE. Both expect a format like: "1112911993 -0700" (unix timestamp + timezone info).

And how do you actually set those variables? Sorry to ask such a trivial question but it's been an hour that i'm going through the doc for such a simple feature. I thought those were environment variables ... but they are not seen under git var -l. Thank you.

2009/10/27 Miklos Vajna <vmiklos@frugalware.org>:

Alex K wrote:

As you suspected, they are environment variables.

i.e. :

$ GIT_AUTHOR_DATE="1112911993 -0700" git commit x

Hope that helps.

Rogan

Rogan Dawes wrote:

Since this was in the context of git-filter-branch, I should point out that you'll have to use the variables with --env-filter and (like the manpage says) make sure you export them.

So to change the date of a single commit with SHA1 <sha1>, you could say

git filter-branch --env-filter '
  if [ $GIT_COMMIT = <sha1> ]; then
    export GIT_AUTHOR_DATE="1112911993 -0700"
    export GIT_COMMITTER_DATE="1112911993 -0700"
  fi
' <other_arguments>

Alex K wrote:

I'm not sure if you're referring to setting the variables or actually rewriting the commits here, but anyway:

The reason why the latter is so hard is that rewriting "old" history is a _huge_ hassle for people who already have the previous version of that history.

That being said, _why_? The dates are never a guarantee that something happened earlier or later precisely because they can easily be modified at commit time. So nobody should take them as more than a hint, and there's little use in faking hints.