Using a Save Hook for an Automatically Updating "Last Modified" Timestamp

There are multiple ways that save hooks on GNU Emacs can be used for automatically updating timestamps. By default, Emacs will update timestamps in the first eight lines of a file. The lines would look like either: Time-stamp: <> Or: Time-stamp: "" In order for the timestamp to automatically change when you save a document, you need to add the save hook to your ~/.emacs file: (add-hook 'before-save-hook 'time-stamp) This is not the only way your timestamp can work, especially since it may be a bit awkward to look at an HTML document. Another way you can display timestamps would be how I do with my own web pages. To do this, you'll need to add the below code block to your .emacs file. (add-hook 'html-mode-hook (lambda () (set (make-local-variable 'time-stamp-pattern) "-8/+%3a %d %3b %:y %02H:%02M:%02S %p %Z"))) The above code will look in the last 8 lines of the document, and will add the time stamp in between the below comments:   Notes:

HTML mode hook based on the example from Emacs wiki.
The article's and web site's former use of  and  were cribbed from Simon Tatham's Home Page. They seemed to be logical names to give to the start and end indicators.
Mentions of ~/ for the .emacs file path refer to your user home directory.
I previously, years ago, tried to use a JavaScript script to do a similar thing to the Emacs save hook (it would've shown "Last modified: " for this web page). I simply do not write last modified dates on the pages anymore. If you would like to see it still, you may use your browser's debugging tools to view the connection headers.
While the JavaScript timestamps may look easier, especially since they do not require GNU Emacs to work, they do not work on platforms like GitHub pages that regenerate the entire web site on every tiny change. See Dr. O'Neil's web site if you need proof of this.

Anton McClure / anton@aperture.nonpaged.com