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28 .\" @(#)pty.4 8.2 (Berkeley) 11/30/93
29 .\" $FreeBSD: src/share/man/man4/pty.4,v 1.8.2.3 2001/08/17 13:08:39 ru Exp $
30 .\" $DragonFly: src/share/man/man4/pty.4,v 1.2 2003/06/17 04:36:59 dillon Exp $
37 .Nd pseudo terminal driver
39 .Cd "pseudo-device pty"
43 driver provides support for a device-pair termed a
45 A pseudo terminal is a pair of character devices, a
49 device. The slave device provides to a process
50 an interface identical
53 However, whereas all other devices which provide the
54 interface described in
56 have a hardware device of some sort behind them, the slave
57 device has, instead, another process manipulating
58 it through the master half of the pseudo terminal.
59 That is, anything written on the master device is
60 given to the slave device as input and anything written
61 on the slave device is presented as input on the master
66 calls apply only to pseudo terminals:
67 .Bl -tag -width ".Dv TIOCREMOTE"
69 Stops output to a terminal (e.g. like typing
74 Restarts output (stopped by
82 mode. Packet mode is enabled by specifying (by reference)
83 a nonzero parameter and disabled by specifying (by reference)
84 a zero parameter. When applied to the master side of a pseudo
85 terminal, each subsequent
87 from the terminal will return data written on the slave part of
88 the pseudo terminal preceded by a zero byte (symbolically
91 or a single byte reflecting control
92 status information. In the latter case, the byte is an inclusive-or
93 of zero or more of the bits:
94 .Bl -tag -width TIOCPKT_FLUSHWRITE
95 .It Dv TIOCPKT_FLUSHREAD
96 whenever the read queue for the terminal is flushed.
97 .It Dv TIOCPKT_FLUSHWRITE
98 whenever the write queue for the terminal is flushed.
100 whenever output to the terminal is stopped a la
103 whenever output to the terminal is restarted.
104 .It Dv TIOCPKT_DOSTOP
113 .It Dv TIOCPKT_NOSTOP
114 whenever the start and stop characters are not
117 While this mode is in use, the presence of control status information
118 to be read from the master side may be detected by a
120 for exceptional conditions.
126 to implement a remote-echoed, locally
129 remote login with proper back-flushing of output; it can be
130 used by other similar programs.
133 Enable/disable a mode that allows a small number of simple user
135 commands to be passed through the pseudo-terminal,
136 using a protocol similar to that of
142 modes are mutually exclusive.
143 This mode is enabled from the master side of a pseudo terminal
144 by specifying (by reference)
145 a nonzero parameter and disabled by specifying (by reference)
149 from the master side will return data written on the slave part of
150 the pseudo terminal preceded by a zero byte,
151 or a single byte reflecting a user control operation on the slave side.
152 A user control command consists of a special
154 operation with no data; the command is given as
158 is a number in the range 1-255.
161 will be received as a single byte on the next
163 from the master side.
167 is a no-op that may be used to probe for
168 the existence of this facility.
171 mode, command operations may be detected with a
173 for exceptional conditions.
175 A mode for the master half of a pseudo terminal, independent
178 This mode causes input to the pseudo terminal
179 to be flow controlled and not input edited (regardless of the
180 terminal mode). Each write to the control terminal produces
181 a record boundary for the process reading the terminal. In
182 normal usage, a write of data is like the data typed as a line
183 on the terminal; a write of 0 bytes is like typing an end-of-file
186 can be used when doing remote line
187 editing in a window manager, or whenever flow controlled input
191 .Bl -tag -width /dev/tty[p-sP-S][0-9a-v]x -compact
192 .It Pa /dev/pty[p-sP-S][0-9a-v]
193 master pseudo terminals
194 .It Pa /dev/tty[p-sP-S][0-9a-v]
195 slave pseudo terminals