For Gnome 45+
ISO Clock is a Gnome extension that changes the clock to an ISO8601 style date format (yyyy-mm-dd)
To install, visit the Gnome Extensions website: https://extensions.gnome.org/extension/7126/iso-clock/
This extension uses settings from the Gnome Settings app
- Added support for day of the week and AM/PM display based on preferences
This is an update to S410's original 'iso8601ish' clock extension, which can be found: here