Pty ports and TIOCUCNTL mode

[Doug Gwyn]

In article <576 at modular.UUCP> olson at modular.UUCP (Jon Olson) writes:
>Does anyone know anything about the TIOCUCNTL mode for Unix pty ports?

ioctl(fd, TIOCUCNTL, &flag) enables (if flag nonzero) or disables (if flag zero)
the transmission of ioctl information through a pty.  Unfortunately only one byte
of ioctl information can be transmitted per ioctl.

The main use of TIOCUCNTL is for user-mode terminal multiplexing, as in the
"mpx" utility that supports AT&T Teletype 5620 or 630 dot-mapped display
terminals in their "layers" mode of operation.  It is the analogue of JSMPX
in the "xt" kernel-multiplexing version.