The following setting display the date in Gregorian calendar in the mode line.

(setq display-time-day-and-date t)

My question is how to change the above settings for date to be shown in the Julian calendar?

  • 1
    Does the display-time-format variable help you?
    – giordano
    Commented Jan 14, 2015 at 14:34

1 Answer 1


You can compute arbitrary date strings by overriding display-time-string-forms.

The documentation says this:

List of expressions governing display of the time in the mode line. For most purposes, you can control the time format using `display-time-format' which is a more standard interface.

This expression is a list of expressions that can involve the keywords load, day, month, and year, 12-hours, 24-hours, minutes, seconds, all numbers in string form, and monthname, dayname, am-pm, and time-zone all alphabetic strings, and mail a true/nil value.

For example, the form

'((substring year -2) "/" month "/" day
  " " 24-hours ":" minutes ":" seconds
  (if time-zone " (") time-zone (if time-zone ")")
  (if mail " Mail" ""))

would give mode line times like `94/12/30 21:07:48 (UTC)'.

To display the Julian date as provided by calendar try this:

(require 'calendar)
(setq display-time-string-forms
  • by Julian date, I mean the default Julian date of Emacs. That can be given by M-x calendar then M-x calendar-julian-print-date.
    – Name
    Commented Jan 14, 2015 at 16:15
  • I'm not familiar with Julian dates, but please see my updated answer. You can use display-time-string-forms to call calendar-julian-date-string on the Gregorian date.
    – user2005
    Commented Jan 14, 2015 at 19:37
  • Thank you. (require 'calendar) should be added. By the way what is the value now. When restarting Emacs, the displaying time becomes different. I think without now it would be fine.
    – Name
    Commented Jan 14, 2015 at 21:00
  • now has the value of evaluating (current-time).
    – user2005
    Commented Jan 14, 2015 at 21:37

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