On 11/28/17, Andrew Warkentin <andreww591(a)gmail.com> wrote:
Multics had dash options, so that's presumably where Unix got them
from. I believe slash options were mostly a DEC thing that DOS and its
successors borrowed (I think they originated in TOPS-10).
That's how I remember it. I think slash was chosen because it looks
somewhat like a toggle switch. MS/DOS patterned its command line
syntax after RT-11 and inherited the slash as a command option
introduction from there. Unfortunately this meant that they couldn't
use slash as a directory separator when they got a hierarchical file
system, and so they chose backslash instead. Nowadays the Windows
shell, and I think also the underlying image activation system
service, use an ugly algorithmic hack to support both directions of
slashes in file pathnames.