> Here are the commands:

> stty -F /dev/ttyUSB0 19200 raw parenb parodd

> cat /dev/ttyUSB0 > /tmp/tekrecv

> # in another terminal:

> tail -f /tmp/tekrecv

> Running these commands, we get these files with wildly varying sizes

I think something is missing there or I don’t get how to get the different file formats with just these commands.

Updated the article to clarify that you pick the format in the menu on the scope itself.

The file formats are produced on another end of the RS232 cable. That particular oscilloscope can send screenshots over that cable, in various formats.

Exactly. You pick the format in the menu on the oscilloscope itself (the menu can be seen in the screencap).