pty.c in 4.1BSD ?

[david at vaxwalle.UUCP]

In /sys/dev of 4.1BSD, there is a driver for the pseudo-device pty.
The only description of it is in the source - no manual page, etc.:

 * A pseudo-teletype is a special device which is not unlike a pipe.
 * It is used to communicate between two processes.  However, it allows
 * one to simulate a teletype, including mode setting, interrupt, and
 * multiple end of files (all not possible on a pipe).	There are
 * really two drivers here.  One is the device which looks like a TTY
 * and can be thought of as the slave device, and hence its routines
 * are prefixed with 'pts' (PTY Slave).	 The other driver can be
 * thought of as the controlling device, and its routines are prefixed
 * by 'ptc' (PTY Controller).  To type on the simulated keyboard of the
 * PTY, one does a 'write' to the controlling device.  To get the
 * simulated printout from the PTY, one does a 'read' on the controlling
 * device.  Normally, the controlling device is called 'ptyx' and the
 * slave device is called 'ttyx' (to make programs like 'who' happy).

Has anyone ever used it? What type of applications could it be used for?
And (most importantly) does it work?

Thanks in advance
	David Brown  (415) 945-2199
	Varian Instruments 2700 Mitchell Dr Walnut Creek CA 94598
	{zehntel,fortune,amd70}!varian!david