[TUHS] The 'usage: ...' message. (Was: On Bloat...)

[Ralph Corderoy]

Hi,

I wrote:
> Another point against adding --help: there's a second attempt to
> describe the source.

It occurred to me --help's the third attempt as there's already ‘usage:
argv[0] ...’.  Back when running man took time and paper, I can see
a one-line summary to aid memory was useful.  I wondered when it first
appeared.

I've found V2, https://www.tuhs.org/cgi-bin/utree.pl?file=V2/cmd, has
cmp.s with

    cmp     (sp)+,$3
    beq     1f
    jsr     r5,mesg; <Usage: cmp arg1 arg2\n\0>; .even
    sys     exit

And cp.c has

    if(argc != 3) {
	    write(1,"Usage: cp oldfile newfile\n",26);
	    exit();
    }

Given the lack of options, the need for a usage message surprises me.
But then ‘cp a-src a-dest b-src b-dest ...’ used to copy files in pairs.
Perhaps when this was dropped, one too many losses?, the usage was
needed to remind users of the change.

Any earlier Unix examples known by the list?
And was ‘usage: ...’ adopted from an earlier system?

-- 
Cheers, Ralph.