OT? want to save web page image automatically

[Peter Flynn]

On 10/11/2020 20:58, Dave Stevens wrote:
> On Tue, 10 Nov 2020 08:49:56 +0000
> David Fletcher <dave at thefletchers.net> wrote:
> 
>> On Mon, 2020-11-09 at 16:40 -0800, Dave Stevens wrote:
>>> I have a web page that displays a chart of values that change once
>>> per
>>> hour. It it uses chart.js under node.js on mint.
>>>
>>> See it here: http://209.145.101.163/24chart.html
>>>
>>> If I right click on the image I have an option (in Firefox) to save
>>> it
>>> as a png. That works fine. What I'd like to do is save the image
>>> once per hour without intervention. Does anyone know a scriptable
>>> method?

AFAIK you can run FF from the command line with an option to open a page 
and screenshot it.

https://developer.mozilla.org/en-US/docs/Mozilla/Firefox/Headless_mode

Basically, create a special profile first (in about:profiles), and then

$ firefox -P <profilename> --screenshot webpage.jpg https://whatever/ --exit

This creates a (potentially VERY tall, narrow) screenshot of the whole 
page, exactly like Vivaldi's pageshot button does. Excellent for making 
screenshot for documentation.

Peter