argc[argv] and Berknet

[gwyn%brl-vld at sri-unix.UUCP]

From:      Doug Gwyn (VLD/VMB) <gwyn at brl-vld>

There is no mystery about	argc[argv] = 0;
pre-7th Edition PDP-11 UNIX exec marked the end of the arguments with
a 16-bit constant -1 and newer UNIXes mark the end of the argument list
with a (char *)0.  The run-time start-off looks for this terminator to
determine argc to pass to main().  The above code merely patches a 6th
Edition image so that *argv++ can be easily used to pick up arguments
and test for the last argument.  (Not recommended.)