coap-client(5) on Linux
The text b0eb07e5d3b2, as Debian 9 (Stretch) shipped it.
CoAP Client based on libcoap
Flags it lists
-
-A -
-B -
-N -
-O -
-P -
-T -
-U -
-a -
-b -
-e -
-f -
-m -
-o -
-p -
-s -
-t -
-v