结合Andrew Sohn的回答(https://stackoverflow.com/a/14265207/1929406)

branchcreated=$(git reflog show --date=format:'%Y-%m-%d %H:%M:%S' --all | sed 's!^.*refs/!refs/!' | grep '/master' | tail -1| cut -d'{' -f 2| cut -d'}' -f 1 | xargs)
echo $branchcreated

正如在评论和Jackub的回答中指出的那样，只要你的分支比配置设置gc中设置的天数更年轻。Reflogexpire(默认值是90天)，然后您可以使用reflog来查找分支引用第一次创建的时间。

注意，git reflog可以接受大多数git日志标志。进一步注意，HEAD@{0}样式选择器是有效的时间概念，实际上是作为日期字符串处理的(以一种hack的方式)。这意味着你可以使用标记——date=local并得到如下输出:

$ git reflog --date=local
763008c HEAD@{Fri Aug 20 10:09:18 2010}: pull : Fast-forward
f6cec0a HEAD@{Tue Aug 10 09:37:55 2010}: pull : Fast-forward
e9e70bc HEAD@{Thu Feb 4 02:51:10 2010}: pull : Fast forward
836f48c HEAD@{Thu Jan 21 14:08:14 2010}: checkout: moving from master to master
836f48c HEAD@{Thu Jan 21 14:08:10 2010}: pull : Fast forward
24bc734 HEAD@{Wed Jan 20 12:05:45 2010}: checkout: moving from 74fca6a42863ffacaf7ba6f1936a9f228950f657 
74fca6a HEAD@{Wed Jan 20 11:55:43 2010}: checkout: moving from master to v2.6.31
24bc734 HEAD@{Wed Jan 20 11:44:42 2010}: pull : Fast forward
964fe08 HEAD@{Mon Oct 26 15:29:29 2009}: checkout: moving from 4a6908a3a050aacc9c3a2f36b276b46c0629ad91 
4a6908a HEAD@{Mon Oct 26 14:52:12 2009}: checkout: moving from master to v2.6.28

有时使用——date=relative也很有用:

$ git reflog --date=relative
763008c HEAD@{4 weeks ago}: pull : Fast-forward
f6cec0a HEAD@{6 weeks ago}: pull : Fast-forward
e9e70bc HEAD@{8 months ago}: pull : Fast forward
836f48c HEAD@{8 months ago}: checkout: moving from master to master
836f48c HEAD@{8 months ago}: pull : Fast forward
24bc734 HEAD@{8 months ago}: checkout: moving from 74fca6a42863ffacaf7ba6f1936a9f228950f657 to master
74fca6a HEAD@{8 months ago}: checkout: moving from master to v2.6.31
24bc734 HEAD@{8 months ago}: pull : Fast forward
964fe08 HEAD@{11 months ago}: checkout: moving from 4a6908a3a050aacc9c3a2f36b276b46c0629ad91 to master
4a6908a HEAD@{11 months ago}: checkout: moving from master to v2.6.28

最后注意:——all标志(实际上是git-reflog理解的git-log标志)将显示refs/中所有已知引用的reflogs(而不是简单的HEAD)，这将清楚地显示分支事件:

git reflog --date=local --all
860e4e4 refs/heads/master@{Sun Sep 19 23:00:30 2010}: commit: Second.
17695bc refs/heads/example_branch@{Mon Sep 20 00:31:06 2010}: branch: Created from HEAD

我找到了最好的方法: 我总是检查用这种方法创建的最新分支

git for-each-ref --sort=-committerdate refs/heads/

试试这个

  git for-each-ref --format='%(committerdate) %09 %(authorname) %09 %(refname)'

如何通过Github GUI知道

我展示了所有的答案，没有人用UI给出答案。如果有人想看到分支是通过Github UI创建的。

进入洞察标签。 在侧栏中选择Network选项卡。

您可以看到分支的创建，如下所示

Use:

git reflog

在当前文件夹中显示存储库的所有生命周期。 首先出现的分支名称(从下到上)是创建的源。

855a3ce HEAD@{0}: checkout: moving from development to feature-sut-46
855a3ce HEAD@{1}: checkout: moving from feature-sut-46 to development
855a3ce HEAD@{2}: checkout: moving from feature-jira35 to feature-sut-46
535dd9d HEAD@{3}: checkout: moving from feature-sut-46 to feature-jira35
855a3ce HEAD@{4}: checkout: moving from development to feature-sut-46
855a3ce HEAD@{5}: checkout: moving from feature-jira35 to development
535dd9d HEAD@{6}: commit: insert the format for vendor specific brower - screen.css
855a3ce HEAD@{7}: checkout: moving from development to feature-jira35
855a3ce HEAD@{8}: checkout: moving from master to development

这意味着:

从master创建分支开发(checkout -b) 分支feature-jira35从开发中创建(checkout -b) 分支特性-jira-sut-46从开发中创建(签出-b)