PTY(4) COMMAND REFERENCE PTY(4)
NAME
pty - pseudo terminal driver
SYNOPSIS
#include <sys/ioctl.h>
DESCRIPTION
The pty driver provides support for a device-pair termed a
pseudo terminal. A pseudo terminal is a pair of character
devices, a master device and a slave device. The slave
device provides processes an interface identical to that
described in tty(4). However, whereas all other devices
which provide the interface described in tty(4) have a
hardware device of some sort behind them, the slave device
has, instead, another process manipulating it through the
master half of the pseudo terminal. That is, anything
written on the master device is given to the slave device as
input and anything written on the slave device is presented
as input on the master device.
The following ioctl calls apply only to pseudo terminals:
TIOCSTOP
Stops output to a terminal (e.g., like typing ^S).
Takes no parameter.
TIOCSTART
Restarts output (stopped by TIOCSTOP or by typing ^S).
Takes no parameter.
TIOCPKT
Enable/disable packet mode. Packet mode is enabled by
specifying (by reference) a nonzero parameter and
disabled by specifying (by reference) a zero parameter.
When applied to the master side of a pseudo terminal,
each subsequent read from the terminal will return data
written on the slave part of the pseudo terminal
preceded by a zero byte (symbolically defined as
TIOCPKT_DATA), or a single byte reflecting control
status information. In the latter case, the byte is an
inclusive-or of zero or more of the bits:
TIOCPKT_FLUSHREAD
whenever the read queue for the terminal is
flushed.
TIOCPKT_FLUSHWRITE
whenever the write queue for the terminal is
flushed.
TIOCPKT_STOP
whenever output to the terminal is stopped a la
Printed 10/17/86 1
PTY(4) COMMAND REFERENCE PTY(4)
^S.
TIOCPKT_START
whenever output to the terminal is restarted.
TIOCPKT_DOSTOP
whenever t_stopc is ^S and t_startc is ^Q.
TIOCPKT_NOSTOP
whenever the start and stop characters are not
^S/^Q.
This mode is used by rlogin(1C) and rlogind(8C) to
implement a remote-echoed, locally ^S/^Q flow-
controlled remote login with proper back-flushing of
output; it can be used by other similar programs.
TIOCREMOTE
A mode for the master half of a pseudo terminal,
independent of TIOCPKT. This mode causes input to the
pseudo terminal to be flow controlled and not input
edited (regardless of the terminal mode). Each write
to the control terminal produces a record boundary for
the process reading the terminal. In normal usage, a
write of data is like the data typed as a line on the
terminal; a write of 0 bytes is like typing an end-of-
file character. TIOCREMOTE can be used when doing
remote line editing in a window manager, or whenever
flow controlled input is required.
FILES
/dev/pty* master pseudo terminals
/dev/ttyp* slave pseudo terminals
DIAGNOSTICS
None.
CAVEATS
It is not possible to send an EOT.
Pseudo terminals will be replaced by a more efficient
mechanism in a future version of UTek.
Printed 10/17/86 2
%%index%%
na:72,64;
sy:136,212;
de:348,2129;2621,1288;
fi:3909,119;
di:4028,90;
ca:4118,204;
%%index%%000000000116