pty.4

来自「<B>Digital的Unix操作系统VAX 4.2源码</B>」· 4 代码 · 共 131 行

.\" SCCSID: @(#)pty.4	3.1	11/24/87
.TH pty 4
.SH Name
pty \- pseudoterminal driver
.SH Syntax
\fBpseudo-device pty[\|\fIn\fB\|]\fR
.SH Description
.NXR "pty interface"
.NXR "pseudoterminal interface"
.NXR "pseudoterminal" "defined"
.NXR "slave pseudoterminal" "defined"
.NXR "master pseudoterminal" "defined"
The
.PN pty
driver provides support for a device-pair termed a
.I pseudoterminal.
A pseudoterminal is a pair of character devices, a
.I master
device and a
.I slave
device.  The slave device provides processes with
an interface identical
to that described in 
.MS tty 4 .
However, whereas all other devices that provide the 
interface described in 
.MS 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 pseudoterminal.
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 slave device can be opened multiple times, while the master
half can be opened only once.
.PP
If no optional \fIn\fR value is given defining
the number of pseudoterminal pairs to be configured, 
16 pseudoterminal pairs are configured.
All pseudoterminal lines should have a corresponding entry in the
/etc/ttys file.  This must be done to insure that logins that use 
pseudoterminals will be tracked in the utmp and wtmp files.
.PP
The following 
.PN ioctl
calls apply only to pseudoterminals:
.NXR "pseudoterminal interface" "ioctl list"
.TP
TIOCSTOP
Stops output to a terminal (for example, like typing CTRL/S).  Takes
no parameter.
.TP
TIOCSTART
Restarts output (stopped by TIOCSTOP or by typing CTRL/S).
Takes no parameter.
.TP
TIOCPKT
Enable/disable 
.I 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 pseudoterminal, 
each subsequent 
.PN read 
from the terminal will return data written on the slave part of
the pseudoterminal 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:
.RS
.TP
TIOCPKT_FLUSHREAD
whenever the read queue for the terminal is flushed.
.TP
TIOCPKT_FLUSHWRITE
whenever the write queue for the terminal is flushed.
.TP
TIOCPKT_STOP
whenever output to the terminal is stopped by typing CTRL/S.
.TP
TIOCPKT_START
whenever output to the terminal is restarted.
.TP
TIOCPKT_DOSTOP
whenever 
the stop character
is CTRL/S
and 
the start character
is CTRL/Q.
.TP
TIOCPKT_NOSTOP
whenever the start and stop characters are not CTRL/S and/or CTRL/Q.
.RE
.IP
This mode is used by 
.MS rlogin 1c
and
.MS rlogind 8c
to implement a remote-echoed, locally flow-controlled (using CTRL/S
or CTRL/Q, or both) remote login with proper back-flushing of output.
It can be used by other similar programs.
.TP
TIOCREMOTE
A mode for the master half of a pseudoterminal, independent
of TIOCPKT.  This mode causes input to the pseudoterminal
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.
.TP
TIOCMASTER
Allows the master to have complete control over the pseudoterminal and
causes the slave side to sleep until the master relinquishes control.
This is useful in preventing changes on the pseudoterminal from
going undetected and being reset by the master.
.SH Files
.TP 15
.PN /dev/pty??
(master pseudoterminals)
.TP
.PN /dev/tty??
(slave pseudoterminals)
.SH See Also
tty(4), MAKEDEV(8)