Just the Code
# Set the HEAD to the old commit that we want to tag
git checkout 9fceb02
# temporarily set the date to the date of the HEAD commit, and add the tag
GIT_COMMITTER_DATE="$(git show --format=%aD | head -1)" \
git tag -a v1.2 -m"v1.2"
# push to origin
git push origin --tags
# set HEAD back to whatever you want it to be
git checkout master
Details
The answer by @dkinzer creates tags whose date is the current date (when you ran the git tag
command), not the date of the commit. The Git help for tag
has a section "On Backdating Tags" which says:
If you have imported some changes from another VCS and would like to add tags for major releases of your work, it is useful to be able to specify the date to embed inside of the tag object; such data in the tag object affects, for example, the ordering of tags in the gitweb interface.
To set the date used in future tag objects, set the environment variable GIT_COMMITTER_DATE
(see the later discussion of possible values; the most common form is "YYYY-MM-DD HH:MM").
For example:
$ GIT_COMMITTER_DATE="2006-10-02 10:31" git tag -s v1.0.1
The page "How to Tag in Git" shows us that we can extract the time of the HEAD commit via:
git show --format=%aD | head -1
#=> Wed, 12 Feb 2014 12:36:47 -0700
We could extract the date of a specific commit via:
GIT_COMMITTER_DATE="$(git show 9fceb02 --format=%aD | head -1)" \
git tag -a v1.2 9fceb02 -m "v1.2"
However, instead of repeating the commit twice, it seems easier to just change the HEAD to that commit and use it implicitly in both commands:
git checkout 9fceb02
GIT_COMMITTER_DATE="$(git show --format=%aD | head -1)" git tag -a v1.2 -m "v1.2"