<p>What commands in Emacs can I use to insert into the text buffer of a file the current date and time?</p>

<p><em>(For example, the equivalent in Notepad is simply pressing F5 which is about the only useful feature for Notepad!)</em></p>

Put in your .emacs file:
```
```
;; ====================
;; insert date and time

(defvar current-date-time-format "%a %b %d %H:%M:%S %Z %Y"
  "Format of date to insert with `insert-current-date-time' func
See help of `format-time-string' for possible replacements")

(defvar current-time-format "%a %H:%M:%S"
  "Format of date to insert with `insert-current-time' func.
Note the weekly scope of the command's precision.")

(defun insert-current-date-time ()
  "insert the current date and time into current buffer.
Uses `current-date-time-format' for the formatting the date/time."
       (interactive)
       (insert "==========\n")
;       (insert (let () (comment-start)))
       (insert (format-time-string current-date-time-format (current-time)))
       (insert "\n")
       )

(defun insert-current-time ()
  "insert the current time (1-week scope) into the current buffer."
       (interactive)
       (insert (format-time-string current-time-format (current-time)))
       (insert "\n")
       )

(global-set-key "\C-c\C-d" 'insert-current-date-time)
(global-set-key "\C-c\C-t" 'insert-current-time)
```
```
Reference