How can I make git log order based on author's timestamp?

git version 1.8.4 added an --author-date-order argument to git log; according to the release notes, "the output is topologically sorted and commits in parallel histories are shown intermixed together based on the author timestamp."

Okay, this took me a very long time to figure out (details). In short, I found many examples that were either incomplete or incorrect. The following command does what I think you would expect:

$ git log --pretty="format:%at %C(yellow)commit %H%Creset\nAuthor: %an <%ae>\nDate: %aD\n\n %s\n" | sort -r | cut -d" " -f2- | sed -e "s/\\\n/\\`echo -e '\n\r'`/g" | tr -d '\15\32' | less -R

You can find this script and others in Git Extras on GitHub.

--date-order/--topo-order really just controls the ordering of commits in a revision list when you are viewing multiple branches running alongside another. The "x is-a-parent of y" relationship is always respected, even if your committer/authoring timestamp is in the distant past or future.

You'd need something like git log --pretty="format:%at %H" | sort -g and then feed the hashes back into git log.