I want to change the date/time format on the top panel to a format close to RFC 3339 / ISO 8601, like one of these:
%F %T → 2013-06-24 16:13:00
%F %a %T → 2013-06-24 Mon 16:13:00
%A %F %T → Monday 2013-06-24 16:13:00
I know Unity has a preference somewhere hidden away in dconf, this is how I did it in Unity, but I can't find such a preference for Gnome 3 shell. Preferably, I'd also like to set one of these as my system-wide date/time locale preference.
Open a terminal and set
gsettings set org.gnome.desktop.interface clock-show-date true
YMMW - this did work for me on Fedora 19.
I was ultimately able to achieve my exactly desired format using a GNOME extension made by Daniel Khodabakhsh. Thank you Daniel!
I found that here: https://github.com/Daniel-Khodabakhsh/datetime-format
Screenshot:
Format: %A | %m-%d-%G | %I:%M %p
In addition to what Martin says, the following worked for me on Ubuntu 14.04, where dconf-editor didn't:
gsettings set org.gnome.desktop.interface clock-show-date true
gsettings set org.gnome.desktop.interface clock-show-seconds true
You can try one of these three extensions:
Replaces the default clock with a complete one showing time, date and week day
Replaces the default clock with a one showing date, week, day of week and time.
Format Clock (development discontinued, but apparently working fine in 3.16)
Change top panel clock format.
It says the develpmont has been discontinued, but I tested it, manually editing metadata.json to include 3.18, and it works:
Partial answer:
Although it doesn't look like the panel clock is easy to format, the calendar menu opened by clicking on it is very easy. Here's a quick hack:
$ sudo vim /usr/share/gnome-shell/js/ui/dateMenu.js
(vim or any other text editor.)
Search for ‘B %d, %Y’, and replace with ‘F’. Save. Press Alt+F2, r, Enter, to restart the shell.
Searching the parent directory reveals a few others that might be worth experimenting with:
$ rgrep -I '%B' /usr/share/gnome-shell/js/ui/
but unfortunately, searching for the abbreviated month name in the panel clock returns nothing here:
$ rgrep -I '%b' /usr/share/gnome-shell/
Any changes to these file will probably be overwritten by updates to Gnome, and you may want to keep the originals of files you edit (sudo mv [name].js [name].js.orig).
On Ubuntu 19.10:
gsettings set org.gnome.desktop.interface clock-show-weekday true
gsettings set org.gnome.desktop.interface clock-show-seconds true
etc.
Or, run
dconf-editor
and go to org.gnome.desktop.interface. You will find clock-show-weekday, clock-show-seconds, clock-show-date and others.
