The date function has an option to output dates in rfc3339 format. A successor to this format is rfc9557[0]. RFC 9557 adds additional options to use information from tzdata in the output, in particular dates of the form:
2006-08-14T02:34:56-06:00[America/Guatemala] Would there be willingness to consider a patch that adds this functionality? In additon to changes in date.c changes would be needed in GNUlib as this provides the main functionality and allows for portability through strftime.c can contribute necessary changes to GNULib as well. There has been a little related discussion at: https://lists.gnu.org/archive/html/bug-gnulib/2024-08/msg00007.html GNU/Linux systems using systemd provide timezone information in the form [Region/City], through timedatectl but this is not in rfc9557 form. One may want this functionality on other systems, for example using OpenRC, so having it in the date command would be desirable. Benson [0] https://datatracker.ietf.org/doc/html/rfc9557
