how to add "YYYY-MM-DDThh:mmTZD" format on add-log-time-format

Question

• i am trying to create change log for all files edited on emacs using add-log-time-format
• however, as of now, add-log-time-format provides only 2 formats: 1. ISO8601 date YYMMDD_ 2023-12-12 and 2. current time string Wed Dec 13 00:07:35 2023
• i would like to add time format of YYYY-MM-DDThh:mmTZD as per w3c Date and Time Formats

Answer 1

There are three choices when you customize add-log-time-format (at least since 2015): the two you listed OR you can write your own function and customize add-log-time-format to specify Other with your own function as the value.

The function can be as simple as this:

(defun my/add-log-iso8601-time-string-with-extras (&optional time zone)
  (format-time-string "%Y-%m-%dT%H:%M%:z" time zone))

which can be added to your init file. Then C-h v add-log-time-format will bring up the doc string of the indicated variable. Click the customize link, select the Other radio button, type (or better yet, cut-and-paste) the name of the function in the text box (where, by default, it says ignore), then Apply and save. Then try to add a log entry. You should probably restart Emacs and try it again to make sure everything is set up correctly.