path: root/usr/src/man/man7i/termio.7i

'\" te
.\" Copyright (c) 2005, Sun Microsystems, Inc.  All Rights Reserved.
.\" Copyright (c) 2014, Joyent, Inc.  All Rights Reserved.
.\" Copyright 1989 AT&T
.\" The contents of this file are subject to the terms of the Common Development and Distribution License (the "License").  You may not use this file except in compliance with the License.
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.TH TERMIO 7I "Dec 30, 2016"
.SH NAME
termio \- general terminal interface
.SH SYNOPSIS
.LP
.nf
#include <termio.h>

\fB\fR\fBioctl\fR(\fBint\fR \fIfildes\fR, \fBint\fR \fIrequest\fR, \fBstruct termio *\fR\fIarg\fR);
.fi

.LP
.nf
\fB\fR\fBioctl\fR(\fBint\fR \fIfildes\fR, \fBint\fR \fIrequest\fR, \fBint\fR \fIarg\fR);
.fi

.LP
.nf
#include <termios.h>

\fB\fR\fBioctl\fR(\fBint\fR \fIfildes\fR, \fBint\fR \fIrequest\fR, \fBstruct termios *\fR\fIarg\fR);
.fi

.SH DESCRIPTION
.LP
This release supports a general interface for asynchronous communications ports
that is hardware-independent. The user interface to this functionality is using
function calls (the preferred interface) described in \fBtermios\fR(3C) or
\fBioctl\fR commands described in this section. This section also discusses the
common features of the  terminal subsystem which are relevant with both user
interfaces.
.sp
.LP
When a terminal file is opened, it normally causes the process to wait until a
connection is established. In practice, user programs seldom open terminal
files; they are opened by the system and become a user's standard input,
output, and error files. The first terminal file opened by the session leader
that is not already associated with a session becomes the controlling terminal
for that session. The controlling terminal plays a special role in handling
quit and interrupt signals, as discussed below. The controlling terminal is
inherited by a child process during a \fBfork\fR(2). A process can break this
association by changing its session using \fBsetsid()\fR (see \fBsetsid\fR(2)).
.sp
.LP
A terminal associated with one of these files ordinarily operates in
full-duplex mode. Characters may be typed at any time, even while output is
occurring, and are only lost when the character input buffers of the system
become completely full, which is rare. For example, the number of characters in
the line discipline buffer may exceed {\fBMAX_CANON\fR}  and  \fBIMAXBEL\fR
(see below) is not set, or the user may accumulate { \fBMAX_INPUT\fR} number of
input characters that have not yet been read by some program. When the input
limit is reached, all the characters saved in the buffer up to that point are
thrown away without notice.
.SS "Session Management (Job Control)"
.LP
A control terminal will distinguish one of the process groups in the session
associated with it to be the  foreground process group. All other process
groups in the session are designated as background process groups. This
foreground process group plays a special role in handling signal-generating
input characters, as discussed below. By default, when a controlling terminal
is allocated, the controlling process's process group is assigned  as
foreground process group.
.sp
.LP
Background process groups in the controlling process's session are subject to a
job control line discipline when they attempt to access their controlling
terminal. Process groups can be sent signals that will cause them to stop,
unless they have made other arrangements. An exception is made for members of
orphaned process groups.
.sp
.LP
An orphaned process group is one where the process group (see \fBgetpgid\fR(2))
has no members with a parent in a different process group but sharing the same
controlling terminal. When a member of an orphaned process group attempts to
access its controlling terminal, EIO is returned because there would be no way
to restart the process if it were stopped on one of these signals.
.sp
.LP
If a member of a background process group attempts to read its controlling
terminal, its process group will be sent a  \fBSIGTTIN\fR signal, which will
normally cause the members of that process group to stop. If, however, the
process is ignoring or holding \fBSIGTTIN\fR, or is a member of an orphaned
process group, the read will fail with \fBerrno\fR set to  \fBEIO\fR, and no
signal is sent.
.sp
.LP
If a member of a background process group attempts to write its controlling
terminal and the \fBTOSTOP\fR bit is set in the \fBc_lflag\fR field, its
process group is sent a \fBSIGTTOU\fR signal, which will normally cause the
members of that process group to stop. If, however, the process is ignoring or
holding \fBSIGTTOU\fR, the write will succeed. If the process is not ignoring
or holding \fBSIGTTOU\fR and is a member of an orphaned process group, the
write will fail with  \fBerrno\fR set to  \fBEIO\fR, and no signal will be
sent.
.sp
.LP
If \fBTOSTOP\fR is set and a member of a background process group attempts  to
\fBioctl\fR its controlling terminal, and that \fBioctl\fR will modify terminal
parameters (for example, \fBTCSETA\fR, \fBTCSETAW\fR, \fBTCSETAF\fR, or
\fBTIOCSPGRP)\fR, its process group will be sent a \fBSIGTTOU\fR signal, which
will normally cause the members of that process group to stop. If, however, the
process is ignoring or holding \fBSIGTTOU\fR, the ioctl will succeed. If the
process is not ignoring or holding \fBSIGTTOU\fR and is a member of an orphaned
process group, the write will fail with  \fBerrno\fR set to \fBEIO\fR, and no
signal will be sent.
.SS "Canonical Mode Input Processing"
.LP
Normally, terminal input is processed in units of lines. A line is delimited by
a newline (\fBASCII LF\fR) character, an end-of-file (\fBASCII EOT\fR)
character, or an end-of-line character. This means that a program attempting to
read will block until an entire line has been typed. Also, no matter how many
characters are requested in the read call, at most one line will be returned.
It is not necessary, however, to read a whole line at once; any number of
characters may be requested in a read, even one, without losing information.
.sp
.LP
During input, erase, erase2, and kill processing is normally done. The
\fBERASE\fR and \fBERASE2\fR character (by default, the character \fBDEL\fR for \fBERASE\fR and \fBControl-h\fR for \fBERASE2\fR) erases the last character
typed. The \fBWERASE\fR character (the character  \fBControl-w\fR) erases the
last "word" typed in the current input line (but not any preceding spaces or
tabs). A "word" is defined as a sequence of non-blank characters, with tabs
counted as blanks. None of \fBERASE\fR or \fBERASE2\fR or \fBWERASE\fR will
erase beyond the beginning of the line.  The \fBKILL\fR character (by default,
the character \fBNAK\fR) kills (deletes) the entire input line, and optionally
outputs a newline character. All these characters operate on a key stroke basis,
independent of any backspacing or tabbing that may have been done. The
\fBREPRINT\fR character (the character Control-r) prints a newline followed by
all characters that have not been read. Reprinting also occurs automatically if
characters that would normally be erased from the screen are fouled by program
output. The characters are reprinted as if they were being echoed;
consequencely, if \fBECHO\fR is not set, they are not printed.
.sp
.LP
The \fBERASE\fR, \fBERASE2\fR, and \fBKILL\fR characters may be entered
literally by preceding them with the escape character. In this case, the
escape character is not read.  The erase, erase2, and kill characters may be
changed.
.SS "Non-canonical Mode Input Processing"
.LP
In non-canonical mode input processing, input characters are not assembled into
lines, and erase and kill processing does not occur. The \fBMIN\fR and
\fBTIME\fR values are used to determine how to process the characters received.
.sp
.LP
\fBMIN\fR represents the minimum number of characters that should be received
when the read is satisfied (that is, when the characters are returned to the
user). \fBTIME\fR is a timer of 0.10-second granularity that is used to timeout
bursty and short-term data transmissions. The four possible values for
\fBMIN\fR and \fBTIME\fR and their interactions are described below.
.sp
.ne 2
.na
\fBCase A: MIN > 0, TIME > 0\fR
.ad
.RS 29n
In this case, \fBTIME\fR serves as an intercharacter timer and is activated
after the first character is received.  Since it is an intercharacter timer, it
is reset after a character is received. The interaction between \fBMIN\fR and
\fBTIME\fR is as follows: as soon as one character is received, the
intercharacter timer is started. If  \fBMIN\fR characters are received before
the intercharacter timer expires (note that the timer is reset upon receipt of
each character), the read is satisfied.  If the timer expires before \fBMIN\fR
characters are received, the characters received to that point are returned to
the user. Note that if  \fBTIME\fR expires, at least one character will be
returned because  the timer would not have been enabled unless a character was
received. In this case (MIN > 0, TIME > 0), the read sleeps until the \fBMIN\fR
and \fBTIME\fR mechanisms are activated by the receipt of the first character.
If the number of characters read is less than the number of characters
available, the timer is not reactivated and the subsequent read is satisfied
immediately.
.RE

.sp
.ne 2
.na
\fBCase B: MIN > 0, TIME = 0\fR
.ad
.RS 29n
In this case, since the value of \fBTIME\fR is zero, the timer plays no role
and only \fBMIN\fR is significant.  A pending read is not satisfied until
\fBMIN\fR characters are received (the pending read sleeps until  \fBMIN\fR
characters are received). A program that uses this case to read record based
terminal \fBI/O\fR may block indefinitely in the read operation.
.RE

.sp
.ne 2
.na
\fBCase C: MIN = 0, TIME > 0\fR
.ad
.RS 29n
In this case, since \fBMIN\fR = 0,  \fBTIME\fR no longer represents an
intercharacter timer: it now serves as a read timer that is activated as soon
as a \fBread\fR is done.  A read is satisfied as soon as a single character is
received or the read timer expires. Note that, in this case, if the timer
expires, no character is returned. If the timer does not expire, the only way
the read can be satisfied is if a  character is received. In this case, the
read will not block indefinitely waiting for a character; if no character is
received within \fBTIME\fR *.10 seconds after the read is initiated, the read
returns with zero characters.
.RE

.sp
.ne 2
.na
\fBCase D: MIN = 0, TIME = 0\fR
.ad
.RS 29n
In this case, return is immediate. The minimum of either the number of
characters requested or the number of characters currently available is
returned without waiting for more characters to be input.
.RE

.SS "Comparing Different Cases of MIN, TIME Interaction"
.LP
Some points to note about  \fBMIN\fR and  \fBTIME\fR :
.RS +4
.TP
.ie t \(bu
.el o
In the following explanations, note that the interactions of \fBMIN\fR and
\fBTIME\fR are not symmetric.  For example, when  \fBMIN\fR > 0 and  \fBTIME\fR
= 0,  \fBTIME\fR has no effect. However, in the opposite case, where  \fBMIN\fR
= 0 and \fBTIME\fR > 0, both  \fBMIN\fR and  \fBTIME\fR play a role in that
\fBMIN\fR is satisfied with the receipt of a single character.
.RE
.RS +4
.TP
.ie t \(bu
.el o
Also note that in case A (\fBMIN\fR > 0, \fBTIME\fR > 0), \fBTIME\fR represents
an intercharacter timer,  whereas in case C ( \fBMIN\fR = 0, \fBTIME\fR > 0),
\fBTIME\fR represents a read timer.
.RE
.sp
.LP
These two points highlight the dual purpose of the  \fBMIN/TIME\fR feature.
Cases A and B, where  \fBMIN\fR > 0, exist to handle burst mode activity (for
example, file transfer programs), where a program would like to process at
least \fBMIN\fR characters at a time. In case A, the intercharacter timer is
activated by a user as a safety measure; in case B, the timer is turned off.
.sp
.LP
Cases C and D exist to handle single character, timed transfers. These cases
are readily adaptable to screen-based applications that need to know if a
character is present in the input queue before refreshing the screen. In case
C, the read is timed, whereas in case D, it is not.
.sp
.LP
Another important note is that \fBMIN\fR is always just a minimum.  It does not
denote a record length. For example, if a program does a read of 20 bytes,
\fBMIN\fR is 10, and 25 characters are present, then 20 characters will be
returned to the user.
.SS "Writing Characters"
.LP
When one or more characters are written, they are transmitted to the terminal
as soon as previously written characters have finished typing. Input characters
are echoed as they are typed if echoing has been enabled. If a process produces
characters more rapidly than they can be typed, it will be suspended when its
output queue exceeds some limit. When the queue is drained down to some
threshold, the program is resumed.
.SS "Special Characters"
.LP
Certain characters have special functions on input. These functions and their
default character values are summarized as follows:
.sp
.ne 2
.na
\fB\fBINTR\fR\fR
.ad
.RS 11n
(Control-c or \fBASCII ETX\fR) generates a \fBSIGINT\fR signal. \fBSIGINT\fR is
sent to all foreground processes associated with the controlling terminal.
Normally, each such process is forced to terminate, but arrangements may be
made either to ignore the signal or to receive a trap to an agreed upon
location. (See  \fBsignal.h\fR(3HEAD)).
.RE

.sp
.ne 2
.na
\fB\fBQUIT\fR\fR
.ad
.RS 11n
(Control-| or \fBASCII FS\fR) generates a \fBSIGQUIT\fR signal.  Its treatment
is identical to the interrupt signal except that, unless a receiving process
has made other arrangements, it will not only be terminated but a core image
file (called  \fBcore\fR) will be created in the current working directory.
.RE

.sp
.ne 2
.na
\fB\fBERASE\fR\fR
.ad
.RS 11n
(DEL) erases the preceding character. It does not erase beyond
the start of a line, as delimited by a \fBNL\fR, \fBEOF\fR, \fBEOL\fR, or
\fBEOL2\fR character.
.RE

.sp
.ne 2
.na
\fB\fBERASE2\fR\fR
.ad
.RS 11n
(Control-h or \fBASCII BS\fR) erases the preceding character, with behaviour
identical to that of ERASE.
.RE

.sp
.ne 2
.na
\fB\fBWERASE\fR\fR
.ad
.RS 11n
(Control-w or \fBASCII ETX\fR) erases the preceding "word". It does not erase
beyond the start of a line, as delimited by a \fBNL\fR, \fBEOF\fR, \fBEOL\fR,
or \fBEOL2\fR character.
.RE

.sp
.ne 2
.na
\fB\fBKILL\fR\fR
.ad
.RS 11n
(Control-u or \fBASCII NAK\fR) deletes the entire line, as delimited by a
\fBNL\fR, \fBEOF\fR, \fBEOL\fR, or \fBEOL2\fR character.
.RE

.sp
.ne 2
.na
\fB\fBREPRINT\fR\fR
.ad
.RS 11n
(Control-r or \fBASCII DC2\fR) reprints all characters, preceded by a newline,
that have not been read.
.RE

.sp
.ne 2
.na
\fB\fBEOF\fR\fR
.ad
.RS 11n
(Control-d or \fBASCII EOT\fR) may be used to generate an end-of-file  from a
terminal. When received, all the characters waiting to be read are immediately
passed to the program, without waiting for a newline, and the \fBEOF\fR is
discarded.  Thus, if no characters are waiting (that is, the \fBEOF\fR occurred
at the beginning of a line) zero characters are passed back, which is the
standard end-of-file indication. Unless escaped, the \fBEOF\fR character is not
echoed. Because \fBEOT\fR is the default \fBEOF\fR character, this prevents
terminals that respond to \fBEOT\fR from hanging up.
.RE

.sp
.ne 2
.na
\fB\fBNL\fR\fR
.ad
.RS 11n
(ASCII LF) is the normal line delimiter. It cannot be changed or escaped.
.RE

.sp
.ne 2
.na
\fB\fBEOL\fR\fR
.ad
.RS 11n
(ASCII NULL) is an additional line delimiter, like \fBNL\fR . It is not
normally used.
.RE

.sp
.ne 2
.na
\fB\fBEOL2\fR\fR
.ad
.RS 11n
is another additional line delimiter.
.RE

.sp
.ne 2
.na
\fB\fBSWTCH\fR\fR
.ad
.RS 11n
(Control-z or \fBASCII EM\fR) Header file symbols related to this special
character are present for compatibility purposes only and the kernel takes no
special action on matching SWTCH (except to discard the character).
.RE

.sp
.ne 2
.na
\fB\fBSUSP\fR\fR
.ad
.RS 11n
(Control-z or \fBASCII SUB\fR) generates a  \fBSIGTSTP\fR signal. \fBSIGTSTP\fR
stops all processes in the foreground process group for that terminal.
.RE

.sp
.ne 2
.na
\fB\fBDSUSP\fR\fR
.ad
.RS 11n
(Control-y or \fBASCII EM\fR). It generates a \fBSIGTSTP\fR signal as
\fBSUSP\fR does, but the signal is sent when a process in the foreground
process group attempts to read the \fBDSUSP\fR character, rather than when it
is typed.
.RE

.sp
.ne 2
.na
\fB\fBSTOP\fR\fR
.ad
.RS 11n
(Control-s or \fBASCII DC3\fR) can be used to suspend output temporarily. It is
useful with \fBCRT\fR terminals to prevent output from disappearing before it
can be read. While output is suspended, \fBSTOP\fR characters are ignored and
not read.
.RE

.sp
.ne 2
.na
\fB\fBSTART\fR\fR
.ad
.RS 11n
(Control-q or \fBASCII DC1\fR) is used to resume output. Output has been
suspended by a \fBSTOP\fR character.  While output is not suspended,
\fBSTART\fR characters are ignored and not read.
.RE

.sp
.ne 2
.na
\fB\fBDISCARD\fR\fR
.ad
.RS 11n
(Control-o or \fBASCII SI\fR) causes subsequent output to be discarded. Output
is discarded until another \fBDISCARD\fR character is typed, more input
arrives, or the condition is cleared by a program.
.RE

.sp
.ne 2
.na
\fB\fBSTATUS\fR\fR
.ad
.RS 11n
(Control-t or \fBASCII DC4\fR) generates a \fBSIGINFO\fR signal. Processes with
a handler will output status information when they receive \fBSIGINFO\fR, for
example, \fBdd(1)\fR. If a process does not have a \fBSIGINFO\fR handler, the
signal will be ignored.
.RE

.sp
.ne 2
.na
\fB\fBLNEXT\fR\fR
.ad
.RS 11n
(Control-v or \fBASCII SYN\fR) causes the special meaning of the next character
to be ignored.  This works for all the special characters mentioned above. It
allows characters to be input that would otherwise be interpreted by the system
(for example \fBKILL, QUIT\fR).  The character values for \fBINTR\fR,
\fBQUIT\fR, \fBERASE\fR, \fBERASE2\fR, \fBWERASE\fR, \fBKILL\fR, \fBREPRINT\fR,
\fBEOF\fR, \fBEOL\fR, \fBEOL2\fR, \fBSWTCH\fR, \fBSUSP\fR, \fBDSUSP\fR,
\fBSTOP\fR, \fBSTART\fR, \fBDISCARD\fR, \fBSTATUS\fR, and \fBLNEXT\fR may be
changed to suit individual tastes. If the value of a special control character
is _POSIX_VDISABLE (0), the function of that special control character is
disabled.
The \fBERASE\fR, \fBERASE2\fR, \fBKILL\fR, and \fBEOF\fR characters may be
escaped by a preceding backslash (\e) character, in which case no special
function is done.
Any of the special characters may be preceded by the \fBLNEXT\fR character, in
which case no special function is done.
.RE

.SS "Modem Disconnect"
.LP
When a modem disconnect is detected, a \fBSIGHUP\fR signal is sent to the
terminal's controlling process. Unless other arrangements have been made, these
signals cause the process to terminate. If  \fBSIGHUP\fR is ignored or caught,
any subsequent read returns with an end-of-file indication until the terminal
is closed.
.sp
.LP
If the controlling process is not in the  foreground process group of the
terminal, a \fBSIGTSTP\fR is sent to the terminal's foreground process group.
Unless other arrangements have been made, these signals cause the processes to
stop.
.sp
.LP
Processes in background process groups that attempt to access the controlling
terminal after modem disconnect while the terminal is still allocated to the
session will receive  appropriate \fBSIGTTOU\fR and  \fBSIGTTIN\fR signals.
Unless other arrangements have  been made, this signal causes the processes to
stop.
.sp
.LP
The controlling terminal will remain in this state until it is  reinitialized
with a successful open by the controlling process, or deallocated by the
controlling process.
.SS "Terminal Parameters"
.LP
The parameters that control the behavior of devices and modules providing the
\fBtermios\fR interface are specified by the \fBtermios\fR structure defined by
\fBtermios.h\fR. Several  \fBioctl\fR(2) system calls that fetch or change
these parameters use this structure that contains the following members:
.sp
.in +2
.nf
 tcflag_t c_iflag;  /* input modes */
	tcflag_t	c_oflag;  /* output modes */
	tcflag_t	c_cflag;  /* control modes */
	tcflag_t	c_lflag;  /* local modes */
	cc_t  c_cc[NCCS];  /* control chars */
.fi
.in -2

.sp
.LP
The special control characters are defined by the array \fBc_cc\fR. The
symbolic name \fBNCCS\fR is the size of the Control-character array and is also
defined by \fB<termios.h>\fR\&. The relative positions, subscript names, and
typical default values  for each function are as follows:
.sp

.sp
.TS
box;
c | c | c
l | l | l .
Relative Position	Subscript Name	Typical Default Value
_
0	VINTR	ETX
_
1 	VQUIT	FS
_
2	VERASE	DEL
_
3	VKILL	NAK
_
4	VEOF	EOT
_
5	VEOL	NUL
_
6	VEOL2	NUL
_
7	VWSTCH	NUL
_
8	VSTART	NUL
_
9	VSTOP	DC3
_
10	VSUSP	SUB
_
11	VDSUSP	EM
_
12	VREPRINT	DC2
_
13	VDISCARD	SI
_
14	VWERASE	ETB
_
15	VLNEXT	SYN
_
16	VSTATUS	DC4
_
17	VERASE2	BS
_
18-19	Reserved
.TE

.SS "Input Modes"
.LP
The \fBc_iflag\fR field describes the basic terminal input control:
.sp
.ne 2
.na
\fB\fBIGNBRK\fR\fR
.ad
.RS 11n
 Ignore break condition.
.RE

.sp
.ne 2
.na
\fB\fBBRKINT\fR\fR
.ad
.RS 11n
Signal interrupt on break.
.RE

.sp
.ne 2
.na
\fB\fBIGNPAR\fR\fR
.ad
.RS 11n
Ignore characters with parity errors.
.RE

.sp
.ne 2
.na
\fB\fBPARMRK\fR\fR
.ad
.RS 11n
Mark parity errors.
.RE

.sp
.ne 2
.na
\fB\fBINPCK\fR\fR
.ad
.RS 11n
Enable input parity check.
.RE

.sp
.ne 2
.na
\fB\fBISTRIP\fR\fR
.ad
.RS 11n
Strip character.
.RE

.sp
.ne 2
.na
\fB\fBINLCR\fR\fR
.ad
.RS 11n
Map NL to CR on input.
.RE

.sp
.ne 2
.na
\fB\fBIGNCR\fR\fR
.ad
.RS 11n
Ignore CR.
.RE

.sp
.ne 2
.na
\fB\fBICRNL\fR\fR
.ad
.RS 11n
Map CR to NL on input.
.RE

.sp
.ne 2
.na
\fB\fBIUCLC\fR\fR
.ad
.RS 11n
Map upper-case to lower-case on input.
.RE

.sp
.ne 2
.na
\fB\fBIXON\fR\fR
.ad
.RS 11n
Enable start/stop output control.
.RE

.sp
.ne 2
.na
\fB\fBIXANY\fR\fR
.ad
.RS 11n
Enable any character to restart output.
.RE

.sp
.ne 2
.na
\fB\fBIXOFF\fR\fR
.ad
.RS 11n
Enable start/stop input control.
.RE

.sp
.ne 2
.na
\fB\fBIMAXBEL\fR\fR
.ad
.RS 11n
Echo  \fBBEL\fR on input line too long.
.RE

.sp
.LP
If \fBIGNBRK\fR is set, a break condition (a character framing error with data
all zeros) detected on input is ignored, that is, not put on the input queue
and therefore not read by any process. If \fBIGNBRK\fR is not set and
\fBBRKINT\fR is set, the break condition shall flush the input and output
queues and if the terminal is the controlling terminal of a foreground process
group, the break condition generates a single \fBSIGINT\fR signal to that
foreground process group. If neither \fBIGNBRK\fR nor \fBBRKINT\fR is set, a
break condition is read as a single '\e0' (\fBASCII NULL\fR) character, or if
\fBPARMRK\fR is set, as '\e377', '\e0', c, where '\e377' is a single character
with value 377 octal (0xff hex, 255 decimal), '\e0' is a single character with
value 0, and c is the errored character received.
.sp
.LP
If  \fBIGNPAR\fR is set, a byte with framing or parity errors (other than
break)  is ignored.
.sp
.LP
If \fBPARMRK\fR is set, and \fBIGNPAR\fR is not set, a byte with a framing or
parity error (other than break) is given to the application as the
three-character sequence: '\e377', '\e0', c, where '\e377' is a single
character with value 377 octal (0xff hex, 255 decimal), '\e0' is a single
character with value 0, and c is the errored character received. To avoid
ambiguity in this case, if \fBISTRIP\fR is not set, a valid character
of '\e377' is given to the  application as `\e377.' If neither \fBIGNPAR\fR nor
\fBPARMRK\fR is set, a framing or parity error (other than break) is given to
the application as a single '\e0' (\fBASCII NULL\fR) character.
.sp
.LP
If \fBINPCK\fR is set, input parity checking is enabled. If \fBINPCK\fR is not
set, input parity checking is disabled. This allows output parity generation
without input parity errors.  Note that whether input parity checking is
enabled or disabled is independent of whether parity detection is enabled or
disabled.  If parity detection is enabled but input parity checking is
disabled, the hardware to which the terminal is connected will recognize the
parity bit, but the terminal special file will not check whether this is set
correctly or not.
.sp
.LP
If \fBISTRIP\fR is set, valid input characters are first stripped to seven
bits, otherwise all eight bits are processed.
.sp
.LP
If \fBINLCR\fR is set, a received \fBNL\fR character is translated into a
\fBCR\fR character.  If  \fBIGNCR\fR is set, a received \fBCR\fR character is
ignored (not read).  Otherwise, if \fBICRNL\fR is set, a received \fBCR\fR
character is translated into a \fBNL\fR character.
.sp
.LP
If \fBIUCLC\fR is set, a received upper case, alphabetic character is
translated into the corresponding lower case character.
.sp
.LP
If \fBIXON\fR is set, start/stop output control is enabled. A received
\fBSTOP\fR character suspends output and a received \fBSTART\fR character
restarts output. The \fBSTOP\fR and \fBSTART\fR characters will not be read,
but will merely perform  flow control functions. If \fBIXANY\fR is set, any
input character restarts output that has been suspended.
.sp
.LP
If \fBIXOFF\fR is set, the system transmits a \fBSTOP\fR character when the
input queue is nearly full, and a \fBSTART\fR character when enough input has
been read so that the input queue is nearly empty again.
.sp
.LP
If \fBIMAXBEL\fR is set, the \fBASCII BEL\fR character is echoed if the input
stream overflows. Further input is not stored, but any input already present in
the input stream is not disturbed.  If  \fBIMAXBEL\fR is not set, no \fBBEL\fR
character is echoed, and all input present in the input queue is discarded if
the input stream overflows.
.SS "Output Modes"
.LP
The  \fBc_oflag\fR field specifies the  system treatment of output:
.sp
.ne 2
.na
\fB\fBOPOST\fR\fR
.ad
.RS 10n
Post-process output.
.RE

.sp
.ne 2
.na
\fB\fBOLCUC\fR\fR
.ad
.RS 10n
Map lower case to upper on output.
.RE

.sp
.ne 2
.na
\fB\fBONLCR\fR\fR
.ad
.RS 10n
Map NL to CR-NL on output.
.RE

.sp
.ne 2
.na
\fB\fBOCRNL\fR\fR
.ad
.RS 10n
Map CR to NL on output.
.RE

.sp
.ne 2
.na
\fB\fBONOCR\fR\fR
.ad
.RS 10n
No \fBCR\fR output at column 0.
.RE

.sp
.ne 2
.na
\fB\fBONLRET\fR\fR
.ad
.RS 10n
\fBNL\fR performs \fBCR\fR function.
.RE

.sp
.ne 2
.na
\fB\fBOFILL\fR\fR
.ad
.RS 10n
Use fill characters for delay.
.RE

.sp
.ne 2
.na
\fB\fBOFDEL\fR\fR
.ad
.RS 10n
Fill is \fBDEL\fR, else \fINULL\fR.
.RE

.sp
.ne 2
.na
\fB\fBNLDLY\fR\fR
.ad
.RS 10n
Select newline delays:
.br
.in +2
\fBNL0\fR
.in -2
.br
.in +2
\fBNL1\fR
.in -2
.RE

.sp
.ne 2
.na
\fB\fBCRDLY\fR\fR
.ad
.RS 10n
Select carriage-return delays:
.br
.in +2
\fBCR0\fR
.in -2
.br
.in +2
\fBCR1\fR
.in -2
.br
.in +2
\fBCR2\fR
.in -2
.br
.in +2
\fBCR3\fR
.in -2
.RE

.sp
.ne 2
.na
\fB\fBTABDLY\fR\fR
.ad
.RS 10n
Select horizontal tab delays or tab expansion:
.sp
.ne 2
.na
\fB\fBTAB0\fR\fR
.ad
.RS 9n

.RE

.sp
.ne 2
.na
\fB\fBTAB1\fR\fR
.ad
.RS 9n

.RE

.sp
.ne 2
.na
\fB\fBTAB2\fR\fR
.ad
.RS 9n

.RE

.sp
.ne 2
.na
\fB\fBTAB3\fR\fR
.ad
.RS 9n
Expand tabs to spaces
.RE

.sp
.ne 2
.na
\fB\fBXTABS\fR\fR
.ad
.RS 9n
Expand tabs to spaces
.RE

.RE

.sp
.ne 2
.na
\fB\fBBSDLY\fR\fR
.ad
.RS 10n
Select backspace delays:
.br
.in +2
\fBBS0\fR
.in -2
.br
.in +2
\fBBS1\fR
.in -2
.RE

.sp
.ne 2
.na
\fB\fBVTDLY\fR\fR
.ad
.RS 10n
Select vertical tab delays:
.br
.in +2
\fBVT0\fR
.in -2
.br
.in +2
\fBVT1\fR
.in -2
.RE

.sp
.ne 2
.na
\fB\fBFFDLY\fR\fR
.ad
.RS 10n
Select form feed delays:
.br
.in +2
\fBFF0\fR
.in -2
.br
.in +2
\fBFF1\fR
.in -2
.RE

.sp
.LP
If \fBOPOST\fR is set, output characters are post-processed as indicated by the
remaining flags; otherwise, characters are transmitted without change.
.sp
.LP
If \fBOLCUC\fR is set, a lower case alphabetic character is transmitted as the
corresponding upper case character. This function is often used in conjunction
with \fBIUCLC.\fR
.sp
.LP
If \fBONLCR\fR is set, the \fBNL\fR character is transmitted as the \fBCR-NL\fR
character pair.  If  \fBOCRNL\fR is set, the \fBCR\fR character is transmitted
as the \fBNL\fR character.  If \fBONOCR\fR is set, no \fBCR\fR character is
transmitted when at column 0 (first position). If  \fBONRET\fR is set, the
\fBNL\fR character is assumed to do the carriage-return function; the column
pointer is set to 0 and the delays specified for \fBCR\fR are used.  Otherwise,
the \fBNL\fR character is assumed to do just the line-feed function; the column
pointer remains unchanged. The column pointer is also set to 0 if the \fBCR\fR
character is actually transmitted.
.sp
.LP
The delay bits specify how long transmission stops to allow for mechanical or
other movement when certain characters are sent to the terminal. In all cases,
a value of 0 indicates no delay. If  \fBOFILL\fR is set, fill characters are
transmitted for delay instead of a timed delay. This is useful for high baud
rate terminals that need only a minimal delay.  If  \fBOFDEL\fR is set, the
fill character is \fBDEL\fR ; otherwise it is  \fINULL\fR.
.sp
.LP
If a form-feed or vertical-tab delay is specified, it lasts for about 2
seconds.
.sp
.LP
Newline delay lasts about 0.10 seconds. If \fBONLRET\fR is set, the
carriage-return delays are used instead of the newline delays. If \fBOFILL\fR
is set, two fill characters are transmitted.
.sp
.LP
Carriage-return delay type 1 is dependent on the current column position, type
2 is about 0.10 seconds, and type 3 is about 0.15 seconds. If  \fBOFILL\fR is
set, delay type 1 transmits two fill characters, and type 2 transmits four fill
characters.
.sp
.LP
Horizontal-tab delay type 1 is dependent on the current column position. Type 2
is about 0.10 seconds. Type 3 specifies that tabs are to be expanded into
spaces. If \fBOFILL\fR is set, two fill characters are transmitted for any
delay.
.sp
.LP
Backspace delay lasts about 0.05 seconds. If  \fBOFILL\fR is set, one fill
character is transmitted.
.sp
.LP
The actual delays depend on line speed and system load.
.SS "Control Modes"
.LP
The \fBc_cflag\fR field describes the hardware control of the terminal:
.sp
.ne 2
.na
\fB\fBCBAUD\fR\fR
.ad
.RS 13n
Baud rate:
.RE

.sp
.ne 2
.na
\fB\fBB0\fR\fR
.ad
.RS 13n
Hang up
.RE

.sp
.ne 2
.na
\fB\fBB50\fR\fR
.ad
.RS 13n
50 baud
.RE

.sp
.ne 2
.na
\fB\fBB75\fR\fR
.ad
.RS 13n
75 baud
.RE

.sp
.ne 2
.na
\fB\fBB110\fR\fR
.ad
.RS 13n
110 baud
.RE

.sp
.ne 2
.na
\fB\fBB134\fR\fR
.ad
.RS 13n
134 baud
.RE

.sp
.ne 2
.na
\fB\fBB150\fR\fR
.ad
.RS 13n
150 baud
.RE

.sp
.ne 2
.na
\fB\fBB200\fR\fR
.ad
.RS 13n
200 baud
.RE

.sp
.ne 2
.na
\fB\fBB300\fR\fR
.ad
.RS 13n
300 baud
.RE

.sp
.ne 2
.na
\fB\fBB600\fR\fR
.ad
.RS 13n
600 baud
.RE

.sp
.ne 2
.na
\fB\fBB1200\fR\fR
.ad
.RS 13n
1200 baud
.RE

.sp
.ne 2
.na
\fB\fBB1800\fR\fR
.ad
.RS 13n
1800 baud
.RE

.sp
.ne 2
.na
\fB\fBB2400\fR\fR
.ad
.RS 13n
2400 baud
.RE

.sp
.ne 2
.na
\fB\fBB4800\fR\fR
.ad
.RS 13n
4800 baud
.RE

.sp
.ne 2
.na
\fB\fBB9600\fR\fR
.ad
.RS 13n
9600 baud
.RE

.sp
.ne 2
.na
\fB\fBB19200\fR\fR
.ad
.RS 13n
19200 baud
.RE

.sp
.ne 2
.na
\fB\fBEXTA\fR\fR
.ad
.RS 13n
External A
.RE

.sp
.ne 2
.na
\fB\fBB38400\fR\fR
.ad
.RS 13n
38400 baud
.RE

.sp
.ne 2
.na
\fB\fBEXTB\fR\fR
.ad
.RS 13n
External B
.RE

.sp
.ne 2
.na
\fB\fBB57600\fR\fR
.ad
.RS 13n
57600 baud
.RE

.sp
.ne 2
.na
\fB\fBB76800\fR\fR
.ad
.RS 13n
76800 baud
.RE

.sp
.ne 2
.na
\fB\fBB115200\fR\fR
.ad
.RS 13n
115200 baud
.RE

.sp
.ne 2
.na
\fB\fBB153600\fR\fR
.ad
.RS 13n
153600 baud
.RE

.sp
.ne 2
.na
\fB\fBB230400\fR\fR
.ad
.RS 13n
230400 baud
.RE

.sp
.ne 2
.na
\fB\fBB307200\fR\fR
.ad
.RS 13n
307200 baud
.RE

.sp
.ne 2
.na
\fB\fBB460800\fR\fR
.ad
.RS 13n
460800 baud
.RE

.sp
.ne 2
.na
\fB\fBCSIZE\fR\fR
.ad
.RS 13n
Character size:
.RE

.sp
.ne 2
.na
\fB\fBCS5\fR\fR
.ad
.RS 13n
5 bits
.RE

.sp
.ne 2
.na
\fB\fBCS6\fR\fR
.ad
.RS 13n
6 bits
.RE

.sp
.ne 2
.na
\fB\fBCS7\fR\fR
.ad
.RS 13n
7 bits
.RE

.sp
.ne 2
.na
\fB\fBCS8\fR\fR
.ad
.RS 13n
8 bits
.RE

.sp
.ne 2
.na
\fB\fBCSTOPB\fR\fR
.ad
.RS 13n
Send two stop bits, else one
.RE

.sp
.ne 2
.na
\fB\fBCREAD\fR\fR
.ad
.RS 13n
Enable receiver
.RE

.sp
.ne 2
.na
\fB\fBPARENB\fR\fR
.ad
.RS 13n
Parity enable
.RE

.sp
.ne 2
.na
\fB\fBPARODD\fR\fR
.ad
.RS 13n
Odd parity, else even
.RE

.sp
.ne 2
.na
\fB\fBHUPCL\fR\fR
.ad
.RS 13n
Hang up on last close
.RE

.sp
.ne 2
.na
\fB\fBCLOCAL\fR\fR
.ad
.RS 13n
Local line, else dial-up
.RE

.sp
.ne 2
.na
\fB\fBCIBAUD\fR\fR
.ad
.RS 13n
Input baud rate, if different from output rate
.RE

.sp
.ne 2
.na
\fB\fBPAREXT\fR\fR
.ad
.RS 13n
Extended parity for mark and space parity
.RE

.sp
.ne 2
.na
\fB\fBCRTSXOFF\fR\fR
.ad
.RS 13n
Enable inbound hardware flow control
.RE

.sp
.ne 2
.na
\fB\fBCRTSCTS\fR\fR
.ad
.RS 13n
Enable outbound hardware flow control
.RE

.sp
.ne 2
.na
\fB\fBCBAUDEXT\fR\fR
.ad
.RS 13n
Bit to indicate output speed > B38400
.RE

.sp
.ne 2
.na
\fB\fBCIBAUDEXT\fR\fR
.ad
.RS 13n
Bit to indicate input speed > B38400
.RE

.sp
.LP
The \fBCBAUD\fR bits together with the \fBCBAUDEXT\fR bit specify the output
baud rate. To retrieve the output speed from the \fBtermios\fR structure
pointed to by \fBtermios_p\fR see the following code segment.
.sp
.in +2
.nf
speed_t ospeed;
if (termios_p->c_cflag & CBAUDEXT)
   ospeed = (termios_p->c_cflag & CBAUD) + CBAUD + 1;
else
   ospeed = termios_p->c_cflag & CBAUD;
.fi
.in -2

.sp
.LP
To store the output speed in the termios structure pointed to by
\fBtermios_p\fR see the following code segment.
.sp
.in +2
.nf
speed_t ospeed;
if (ospeed > CBAUD) {
   termios_p->c_cflag |= CBAUDEXT;
   ospeed -= (CBAUD + 1);
} else
   termios_p->c_cflag &= ~CBAUDEXT;
 termios_p->c_cflag =
	(termios_p->c_cflag & ~CBAUD) | (ospeed & CBAUD);
.fi
.in -2

.sp
.LP
The zero baud rate, B0, is used to hang up the connection. If B0 is specified,
the data-terminal-ready signal is not asserted. Normally, this disconnects the
line.
.sp
.LP
If the \fBCIBAUDEXT\fR or \fBCIBAUD\fR bits are not zero, they specify the
input baud rate, with the \fBCBAUDEXT\fR and \fBCBAUD\fR bits specifying the
output baud rate; otherwise, the output and input baud rates are both specified
by the \fBCBAUDEXT\fR and  \fBCBAUD\fR bits.  The values for the \fBCIBAUD\fR
bits are the same as the values for the \fBCBAUD\fR bits, shifted left
\fBIBSHIFT\fR bits. For any particular hardware, impossible speed changes are
ignored. To retrieve the input speed in the  \fBtermios\fR structure pointed to
by  \fBtermios_p\fR see the following code segment.
.sp
.in +2
.nf
speed_t ispeed;
if (termios_p->c_cflag & CIBAUDEXT)
   ispeed = ((termios_p->c_cflag & CIBAUD) >> IBSHIFT)
   + (CIBAUD >> IBSHIFT) + 1;
else
   ispeed = (termios_p->c_cflag & CIBAUD) >> IBSHIFT;
.fi
.in -2

.sp
.LP
To store the input speed in the  \fBtermios\fR structure pointed to by
\fBtermios_p\fR see the following code segment.
.sp
.in +2
.nf
speed_t ispeed;
if (ispeed == 0) {
   ispeed = termios_p->c_cflag & CBAUD;
if (termios_p->c_cflag & CBAUDEXT)
   ispeed += (CBAUD + 1);
}
 if ((ispeed << IBSHIFT) > CIBAUD) {
    termios_p->c_cflag |= CIBAUDEXT;
    ispeed -= ((CIBAUD >> IBSHIFT) + 1);
} else
    termios_p->c_cflag &= ~CIBAUDEXT;
    termios_p->c_cflag =
    (termios_p->c_cflag & ~CIBAUD) |
           ((ispeed << IBSHIFT) & CIBAUD);
.fi
.in -2

.sp
.LP
The \fBCSIZE\fR bits specify the character size in bits for both transmission
and reception. This size does not include the parity bit, if any. If
\fBCSTOPB\fR is set, two stop bits are used; otherwise, one stop bit is used.
For example, at 110 baud, two stops bits are required.
.sp
.LP
If \fBPARENB\fR is set, parity generation and detection is enabled, and a
parity bit is added to each character. If parity is enabled, the \fBPARODD\fR
flag specifies odd parity if set; otherwise, even parity is used.
.sp
.LP
If \fBCREAD\fR is set, the receiver is enabled. Otherwise, no characters are
received.
.sp
.LP
If \fBHUPCL\fR is set, the line is disconnected when the last process with the
line open closes it or terminates. That is, the data-terminal-ready signal is
not asserted.
.sp
.LP
If \fBCLOCAL\fR is set, the line is assumed to be a local, direct connection
with no modem control; otherwise, modem control is assumed.
.sp
.LP
If \fBCRTSXOFF\fR is set, inbound hardware flow control is enabled.
.sp
.LP
If  \fBCRTSCTS\fR is set, outbound hardware flow control is enabled.
.sp
.LP
The four possible combinations for the state of \fBCRTSCTS\fR and
\fBCRTSXOFF\fR bits and their interactions are described below.
.sp
.ne 2
.na
\fBCase A:\fR
.ad
.RS 11n
\fBCRTSCTS\fR off, \fBCRTSXOFF\fR off. In this case the hardware flow control
is disabled.
.RE

.sp
.ne 2
.na
\fBCase B:\fR
.ad
.RS 11n
\fBCRTSCTS\fR on, \fBCRTSXOFF\fR off. In this case only outbound hardware flow
control is enabled. The state of CTS signal is used to do outbound flow
control. It is expected that output will be suspended if CTS is low and resumed
when CTS is high.
.RE

.sp
.ne 2
.na
\fBCase C:\fR
.ad
.RS 11n
\fBCRTSCTS\fR off, \fBCRTSXOFF\fR on. In this case only inbound hardware flow
control is enabled. The state of RTS signal is used to do inbound flow control.
It is expected that input will be suspended if RTS is low and resumed when RTS
is high.
.RE

.sp
.ne 2
.na
\fBCase D:\fR
.ad
.RS 11n
\fBCRTSCTS\fR on, \fBCRTSXOFF\fR on. In this case both inbound and outbound
hardware flow control are enabled. Uses the state of CTS signal to do outbound
flow control and RTS signal to do inbound flow control.
.RE

.SS "Local Modes"
.LP
The \fBc_lflag\fR field of the argument structure is used by the line
discipline to control terminal functions. The basic line discipline provides
the following:
.sp
.ne 2
.na
\fB\fBISIG\fR\fR
.ad
.RS 11n
 Enable signals.
.RE

.sp
.ne 2
.na
\fB\fBICANON\fR\fR
.ad
.RS 11n
Canonical input (erase and kill processing).
.RE

.sp
.ne 2
.na
\fB\fBXCASE\fR\fR
.ad
.RS 11n
Canonical upper/lower presentation.
.RE

.sp
.ne 2
.na
\fB\fBECHO\fR\fR
.ad
.RS 11n
Enable echo.
.RE

.sp
.ne 2
.na
\fB\fBECHOE\fR\fR
.ad
.RS 11n
Echo erase character as \fBBS-SP-BS\fR &.
.RE

.sp
.ne 2
.na
\fB\fBECHOK\fR\fR
.ad
.RS 11n
Echo  \fBNL\fR after kill character.
.RE

.sp
.ne 2
.na
\fB\fBECHONL\fR\fR
.ad
.RS 11n
Echo  \fBNL\fR .
.RE

.sp
.ne 2
.na
\fB\fBNOFLSH\fR\fR
.ad
.RS 11n
Disable flush after interrupt or quit.
.RE

.sp
.ne 2
.na
\fB\fBTOSTOP\fR\fR
.ad
.RS 11n
Send  \fBSIGTTOU\fR for background output.
.RE

.sp
.ne 2
.na
\fB\fBECHOCTL\fR\fR
.ad
.RS 11n
Echo control characters as  \fIchar,\fR delete as ^?.
.RE

.sp
.ne 2
.na
\fB\fBECHOPRT\fR\fR
.ad
.RS 11n
Echo erase character as character erased.
.RE

.sp
.ne 2
.na
\fB\fBECHOKE\fR\fR
.ad
.RS 11n
\fBBS-SP-BS\fR erase entire line on line kill.
.RE

.sp
.ne 2
.na
\fB\fBFLUSHO\fR\fR
.ad
.RS 11n
Output is being flushed.
.RE

.sp
.ne 2
.na
\fB\fBPENDIN\fR\fR
.ad
.RS 11n
Retype pending input at next read or  input character.
.RE

.sp
.ne 2
.na
\fB\fBIEXTEN\fR\fR
.ad
.RS 11n
Enable extended (implementation-defined) functions.
.RE

.sp
.LP
If \fBISIG\fR is set, each input character is checked against the special
control characters INTR, QUIT, SWTCH,  SUSP, STATUS, and \fBDSUSP\fR. If an
input character matches one of these control characters, the function
associated with that character is performed. (Note: If SWTCH is set and the
character matches, the character is simply discarded. No other action is
taken.) If \fBISIG\fR is not set, no checking is done.  Thus, these special
input functions are possible only if \fBISIG\fR is set.
.sp
.LP
If \fBICANON\fR is set, canonical processing is enabled. This enables the erase
and kill edit functions, and the assembly of input characters into lines
delimited by \fBNL-c\fR, \fBEOF\fR, \fBEOL\fR, and \fBEOL\fR . If  \fBICANON\fR
is not set, read requests are satisfied directly from the input queue. A read
is not satisfied until at least \fBMIN\fR characters have been  received or the
timeout value \fBTIME\fR has expired between characters. This allows fast
bursts of input to be read efficiently while still allowing single character
input. The time value represents tenths of seconds.
.sp
.LP
If  \fBXCASE\fR is set and \fBICANON\fR is set, an upper case letter is
accepted on input if preceded by a backslash \fB(\e)\fR character, and is
output preceded by a  backslash \fB(\e)\fR character. In this mode, the
following escape sequences are generated on output and accepted on input:
.sp

.sp
.TS
box;
c | c
l | l .
FOR:	USE:
_
`	\e'
_
|	\e!
_
\(ap	\e^
_
{	\e(
_
}	\e)
_
\e	\e\e
.TE

.sp
.LP
For example, input A as \ea, \en as \e\en, and \eN as \e\e\en.
.sp
.LP
If \fBECHO\fR is set, characters are echoed as received.
.sp
.LP
When \fBICANON\fR is set, the following echo functions are possible.
.RS +4
.TP
.ie t \(bu
.el o
If \fBECHO\fR and \fBECHOE\fR are set, and  \fBECHOPRT\fR is not set,  the
\fBERASE\fR, \fBERASE2\fR, and \fBWERASE\fR characters are echoed as one or
more ASCII BS SP BS, which clears the last character(s) from a \fBCRT\fR screen.
.RE
.RS +4
.TP
.ie t \(bu
.el o
If \fBECHO\fR, \fBECHOPRT\fR, and \fBIEXTEN\fR are set, the first \fBERASE\fR,
\fBERASE2\fR, and \fBWERASE\fR character in a sequence echoes as a backslash
(\fB\e\fR), followed by the characters being erased.  Subsequent \fBERASE\fR and
\fBWERASE\fR characters echo the characters being erased, in reverse order. The
next non-erase character causes a `/' (slash) to be typed before it is echoed.
\fBECHOPRT\fR should be used for hard copy terminals.
.RE
.RS +4
.TP
.ie t \(bu
.el o
If  \fBECHOKE\fR and \fBIEXTEN\fR are set, the kill character is echoed by
erasing each  character on the line from the screen (using the mechanism
selected by \fBECHOE\fR and \fBECHOPR\fRa).
.RE
.RS +4
.TP
.ie t \(bu
.el o
If  \fBECHOK\fR is set, and \fBECHOKE\fR is not set, the \fBNL\fR character is
echoed after the kill character to emphasize that the line is deleted. Note
that a `\' (escape) character or an \fBLNEXT\fR character preceding the erase
or kill character removes any special function.
.RE
.RS +4
.TP
.ie t \(bu
.el o
If  \fBECHONL\fR is set, the \fBNL\fR character is echoed even if  \fBECHO\fR
is not set.  This is useful for terminals set to local echo (so called
half-duplex).
.RE
.sp
.LP
If \fBECHOCTL\fR and \fBIEXTEN\fR are set, all control characters (characters
with codes between 0 and 37 octal) other than  \fBASCII TAB\fR, \fBASCII NL\fR,
the \fBSTART\fR character, and the \fBSTOP\fR character,  \fBASCII CR\fR, and
\fBASCII BS\fR are echoed as ^ \fBX,\fR where \fBX\fR is the character given by
adding 100 octal to the code of the  control character (so that the character
with octal code 1 is echoed as ^ \fBA),\fR and the \fBASCII DEL\fR character,
with code 177 octal, is echoed as ^ \fB?\fR.
.sp
.LP
If  \fBNOFLSH\fR is set, the normal flush of the input and output queues
associated with the \fBINTR\fR, \fBQUIT\fR, \fBSTATUS\fR, and \fBSUSP\fR
characters is not done.  This bit should be set when restarting system calls
that read from or write to a terminal (see  \fBsigaction\fR(2)\|).
.sp
.LP
If  \fBTOSTOP\fR and \fBIEXTEN\fR are set, the signal  \fBSIGTTOU\fR is sent to
a process that tries to write to its controlling terminal if it is not in the
foreground process group for that terminal. This signal normally stops the
process. Otherwise, the output generated by that process is output to the
current output stream. Processes that are blocking or ignoring  \fBSIGTTOU\fR
signals are excepted and allowed to produce output, if any.
.sp
.LP
If \fBFLUSHO\fR and \fBIEXTEN\fR are set, data written to the terminal is
discarded. This bit is set when the \fBFLUSH\fR character is typed. A program
can cancel the effect of typing the \fBFLUSH\fR character by clearing
\fBFLUSHO\fR.
.sp
.LP
If \fBPENDIN\fR and  \fBIEXTEN\fR are set, any input that has not yet been read
is reprinted when the next character arrives as input. \fBPENDIN\fR is then
automatically cleared.
.sp
.LP
If \fBIEXTEN\fR is set, the following implementation-defined functions are
enabled:  special characters ( \fBWERASE\fR, \fBREPRINT\fR, \fBDISCARD\fR, and
\fBLNEXT\fR) and local flags ( \fBTOSTOP\fR, \fBECHOCTL\fR, \fBECHOPRT\fR,
\fBECHOKE\fR, \fBFLUSHO\fR, and \fBPENDIN\fR).
.SS "Minimum and Timeout"
.LP
The \fBMIN\fR and \fBTIME\fR values were described previously, in the
subsection, \fBNon-canonical Mode Input Processing\fR. The initial value of
\fBMIN\fR is 1, and the initial value of \fBTIME\fR is 0.
.SS "Terminal Size"
.LP
The number of lines and columns on the terminal's display is specified in the
\fBwinsize\fR structure defined by  \fBsys/termios.h\fR and includes the
following members:
.sp
.in +2
.nf
unsigned	short ws_row;  /* rows, in characters */
unsigned short	ws_col;    /* columns, in characters */
unsigned short	ws_xpixel; /* horizontal size, in pixels */
unsigned short	ws_ypixel; /* vertical size, in pixels */
.fi
.in -2

.SS "Termio Structure"
.LP
The SunOS/SVR4 \fBtermio\fR structure is used by some \fBioctl\fRs; it is
defined by \fBsys/termio.h\fR and includes the following members:
.sp
.in +2
.nf
unsigned	 short	c_iflag;  /* input modes */
unsigned	 short	c_oflag;  /* output modes */
unsigned	 short	c_cflag;  /* control modes */
unsigned	 short c_lflag; /* local modes */
char c_line;			  /* line discipline */
unsigned	 char  c_cc[NCC];  /* control chars */
.fi
.in -2

.sp
.LP
The special control characters are defined by the array \fBc_cc\fR. The
symbolic name \fBNCC\fR is the size of the Control-character array and is also
defined by \fBtermio.h\fR. The relative positions, subscript names, and typical
default values  for each function are as follows:
.sp

.sp
.TS
box;
c | c | c
l | l | l .
Relative Positions	Subscript Names	Typical Default Values
_
0	VINTR	EXT
_
1	VQUIT	FS
_
2	VERASE	DEL
_
3	VKILL	NAK
_
4	VEOF	EOT
_
5	VEOL	NUL
_
6	VEOL2	NUL
_
7	Reserved	
.TE

.sp
.LP
The \fBMIN\fR values is stored in the \fBVMIN\fR element of the \fBc_cc\fR
array; the \fBTIME\fR value is stored in the  \fBVTIME\fR element of the
\fBc_cc\fR array. The  \fBVMIN\fR element is the same element as the
\fBVEOF\fR element; the \fBVTIME\fR element is the same element as the
\fBVEOL\fR element.
.sp
.LP
The calls that use the \fBtermio\fR structure only affect the flags and control
characters that can be stored in the \fBtermio\fR structure; all other flags
and control characters are unaffected.
.SS "Modem Lines"
.LP
On special files representing serial ports, modem control lines can be read.
Control lines  (if the underlying hardware supports it) may also be changed.
Status lines are read-only. The following modem control and status lines may be
supported by a device; they are defined by \fBsys/termios.h\fR:
.sp
.ne 2
.na
\fB\fBTIOCM_LE\fR\fR
.ad
.RS 13n
 line enable
.RE

.sp
.ne 2
.na
\fB\fBTIOCM_DTR\fR\fR
.ad
.RS 13n
data terminal ready
.RE

.sp
.ne 2
.na
\fB\fBTIOCM_RTS\fR\fR
.ad
.RS 13n
request to send
.RE

.sp
.ne 2
.na
\fB\fBTIOCM_ST\fR\fR
.ad
.RS 13n
secondary transmit
.RE

.sp
.ne 2
.na
\fB\fBTIOCM_SR\fR\fR
.ad
.RS 13n
secondary receive
.RE

.sp
.ne 2
.na
\fB\fBTIOCM_CTS\fR\fR
.ad
.RS 13n
clear to send
.RE

.sp
.ne 2
.na
\fB\fBTIOCM_CAR\fR\fR
.ad
.RS 13n
carrier detect
.RE

.sp
.ne 2
.na
\fB\fBTIOCM_RNG\fR\fR
.ad
.RS 13n
ring
.RE

.sp
.ne 2
.na
\fB\fBTIOCM_DSR\fR\fR
.ad
.RS 13n
data set ready
.RE

.sp
.LP
\fBTIOCM_CD\fR is a synonym for \fBTIOCM_CAR\fR, and \fBTIOCM_RI\fR is a
synonym for \fBTIOCM_RNG\fR. Not all of these are necessarily supported by any
particular device; check the manual page for the device in question.
.sp
.LP
The software carrier mode can be enabled or disabled using the
\fBTIOCSSOFTCAR\fR \fBioctl\fR. If the software carrier flag for a line is off,
the line pays attention to the hardware carrier detect (DCD) signal. The
\fBtty\fR device associated with the line cannot be opened until \fBDCD\fR is
asserted. If the software carrier flag is on, the line behaves as if \fBDCD\fR
is always asserted.
.sp
.LP
The software carrier flag is usually turned on for locally connected terminals
or other devices, and is off for lines with modems.
.sp
.LP
To be able to issue the \fBTIOCGSOFTCAR\fR and \fBTIOCSSOFTCAR\fR \fBioctl\fR
calls, the \fBtty\fR line should be opened with \fBO_NDELAY\fR so that the
\fBopen\fR(2) will not wait for the carrier.
.SS "Default Values"
.LP
The initial  \fBtermios\fR values upon driver open is configurable. This is
accomplished by setting the "ttymodes" property in the file
\fB/kernel/drv/options.conf\fR. Since this property is assigned during system
initialization,  any change to the "ttymodes" property will not take effect
until the next reboot.  The string value assigned to this property should be in
the same format as the output of the \fBstty\fR(1) command with the -g option.
.sp
.LP
If this property is undefined, the following  \fBtermios\fR modes are in
effect.  The initial input control value is \fBBRKINT\fR, \fBICRNL\fR,
\fBIXON\fR, \fBIMAXBEL\fR. The initial output control value is \fBOPOST\fR,
\fBONLCR\fR, \fBTAB3\fR. The initial hardware control value is \fBB9600\fR,
\fBCS8\fR, \fBCREAD\fR. The initial line-discipline control value is
\fBISIG\fR, \fBICANON\fR, \fBIEXTEN\fR, \fBECHO\fR, \fBECHOK\fR, \fBECHOE\fR,
\fBECHOKE\fR, \fBECHOCTL\fR.
.SH IOCTLS
.LP
The \fBioctl\fRs supported by devices and \fBSTREAMS\fR modules providing the
\fBtermios\fR(3C) interface are listed below. Some calls may not be supported
by all devices or modules.  The functionality provided by these calls is also
available through the preferred function call interface specified on
\fBtermios\fR.
.sp
.ne 2
.na
\fB\fBTCGETS\fR\fR
.ad
.RS 16n
The argument is a pointer to a \fBtermios\fR structure. The current terminal
parameters are fetched and stored into that structure.
.RE

.sp
.ne 2
.na
\fB\fBTCSETS\fR\fR
.ad
.RS 16n
The argument is a pointer to a \fBtermios\fR structure. The current terminal
parameters are set from the values stored in that structure. The change is
immediate.
.RE

.sp
.ne 2
.na
\fB\fBTCSETSW\fR\fR
.ad
.RS 16n
The argument is a pointer to a \fBtermios\fR structure. The current terminal
parameters are set from the values stored in that structure. The change occurs
after all characters queued for output have been transmitted. This form should
be used when changing parameters that affect output.
.RE

.sp
.ne 2
.na
\fB\fBTCSETSF\fR\fR
.ad
.RS 16n
The argument is a pointer to a \fBtermios\fR structure. The current terminal
parameters are set from the values stored in that structure. The change occurs
after all characters queued for output have been transmitted; all characters
queued for input are discarded and then the change occurs.
.RE

.sp
.ne 2
.na
\fB\fBTCGETA\fR\fR
.ad
.RS 16n
The argument is a pointer to a \fBtermio\fR structure. The current terminal
parameters are fetched, and those parameters that can be stored in a
\fBtermio\fR structure are stored into that structure.
.RE

.sp
.ne 2
.na
\fB\fBTCSETA\fR\fR
.ad
.RS 16n
The argument is a pointer to a  \fBtermio\fR structure. Those terminal
parameters that can be stored in a \fBtermio\fR structure are set from the
values stored in that structure. The change is immediate.
.RE

.sp
.ne 2
.na
\fB\fBTCSETAW\fR\fR
.ad
.RS 16n
The argument is a pointer to a \fBtermio\fR structure. Those terminal
parameters that can be stored in a \fBtermio\fR structure are set from the
values stored in that structure. The change occurs after all characters queued
for output have been transmitted. This form should be used when changing
parameters that affect output.
.RE

.sp
.ne 2
.na
\fB\fBTCSETAF\fR\fR
.ad
.RS 16n
The argument is a pointer to a \fBtermio\fR structure.  Those terminal
parameters that can be stored in a \fBtermio\fR structure are set from the
values stored in that structure. The change occurs after all characters queued
for output have been transmitted; all characters queued for input are discarded
and then the change occurs.
.RE

.sp
.ne 2
.na
\fB\fBTCSBRK\fR\fR
.ad
.RS 16n
The argument is an \fBint\fR value. Wait for the output to drain. If the
argument is \fB0\fR, then send a break (zero valued bits for 0.25 seconds).
.RE

.sp
.ne 2
.na
\fB\fBTCXONC\fR\fR
.ad
.RS 16n
Start/stop control. The argument is an \fBint\fR value. If the argument is
\fB0\fR, suspend output; if \fB1\fR, restart suspended output; if \fB2\fR,
suspend input; if \fB3\fR, restart suspended input.
.RE

.sp
.ne 2
.na
\fB\fBTCFLSH\fR\fR
.ad
.RS 16n
The argument is an \fBint\fR value. If the argument is \fB0\fR, flush the input
queue; if \fB1\fR, flush the output queue; if \fB2\fR, flush both the input and
output queues.
.RE

.sp
.ne 2
.na
\fB\fBTIOCGPGRP\fR\fR
.ad
.RS 16n
The argument is a pointer to a \fBpid_t\fR. Set the value of that  \fBpid_t\fR
to the process group \fBID\fR of the foreground process group associated with
the terminal. See  \fBtermios\fR(3C) for a description of  \fBTCGETPGRP\fR.
.RE

.sp
.ne 2
.na
\fB\fBTIOCSPGRP\fR\fR
.ad
.RS 16n
The argument is a pointer to a \fBpid_t\fR. Associate the process group whose
process group \fBID\fR is specified by the value of that  \fBpid_t\fR with the
terminal. The new process group value must be in the range of valid process
group \fBID\fR values.  Otherwise, the error  \fBEPERM\fR is returned.
.RE

.sp
.ne 2
.na
\fB\fBTIOCGSID\fR\fR
.ad
.RS 16n
The argument is a pointer to a \fBpid_t\fR. The session ID of the terminal is
fetched  and stored in the  \fBpid_t\fR.
.RE

.sp
.ne 2
.na
\fB\fBTIOCGWINSZ\fR\fR
.ad
.RS 16n
The argument is a pointer to a \fBwinsize\fR structure. The terminal driver's
notion of the terminal size is stored into that structure.
.RE

.sp
.ne 2
.na
\fB\fBTIOCSWINSZ\fR\fR
.ad
.RS 16n
The argument is a pointer to a \fBwinsize\fR structure. The terminal driver's
notion of the terminal size is set from the values specified in that structure.
If the new sizes are different from the old sizes, a \fBSIGWINCH\fR signal is
set to the process group of the terminal.
.RE

.sp
.ne 2
.na
\fB\fBTIOCMBIS\fR\fR
.ad
.RS 16n
The argument is a pointer to an \fBint\fR whose value is a mask containing
modem control lines to be turned on. The control lines whose bits are set in
the argument are turned on; no other control lines are affected.
.RE

.sp
.ne 2
.na
\fB\fBTIOCMBIC\fR\fR
.ad
.RS 16n
The argument is a pointer to an \fBint\fR whose value is a mask containing
modem control lines to be turned off. The control lines whose bits are set in
the argument are turned off; no other control lines are affected.
.RE

.sp
.ne 2
.na
\fB\fBTIOCMGET\fR\fR
.ad
.RS 16n
The argument is a pointer to an  \fBint\fR. The current state of the modem
status lines is fetched and stored in the  \fBint\fR pointed to by the
argument.
.RE

.sp
.ne 2
.na
\fB\fBTIOCMSET\fR\fR
.ad
.RS 16n
The argument is a pointer to an  \fBint\fR containing a new set of modem
control lines. The modem control lines are turned on or off, depending on
whether the bit for that mode is set or clear.
.RE

.sp
.ne 2
.na
\fB\fBTIOCSPPS\fR\fR
.ad
.RS 16n
The argument is a pointer to an \fBint\fR that determines whether
pulse-per-second event handling is to be enabled (non-zero) or disabled (zero).
If a one-pulse-per-second reference clock is attached to the serial line's data
carrier detect input, the local system clock will be calibrated to it. A clock
with a high error, that is, a deviation of more than 25 microseconds per tick,
is ignored.
.RE

.sp
.ne 2
.na
\fB\fBTIOCGPPS\fR\fR
.ad
.RS 16n
The argument is a pointer to an \fBint\fR, in which the state of the even
handling is returned. The \fBint\fR is set to a non-zero value if
pulse-per-second (PPS) handling has been enabled. Otherwise, it is set to zero.
.RE

.sp
.ne 2
.na
\fB\fBTIOCGSOFTCAR\fR\fR
.ad
.RS 16n
The argument is a pointer to an \fBint\fR whose value is \fB1\fR or \fB0\fR,
depending on whether the software carrier detect is turned on or off.
.RE

.sp
.ne 2
.na
\fB\fBTIOCSSOFTCAR\fR\fR
.ad
.RS 16n
The argument is a pointer to an \fBint\fR whose value is \fB1\fR or \fB0\fR.
The value of the integer should be \fB0\fR to turn off software carrier, or
\fB1\fR to turn it on.
.RE

.sp
.ne 2
.na
\fB\fBTIOCGPPSEV\fR\fR
.ad
.RS 16n
The argument is a pointer to a \fBstruct\fR \fBppsclockev\fR. This structure
contains the following members:
.sp
.in +2
.nf
struct timeval tv;
uint32_t serial;
.fi
.in -2

"tv" is the system clock timestamp when the event (pulse on the \fBDCD\fR pin)
occurred. "serial" is the ordinal of the event, which each consecutive event
being assigned the next ordinal. The first event registered gets a "serial"
value of \fB1\fR. The \fBTIOCGPPSEV\fR returns the last event registered;
multiple calls will persistently return the same event until a new one is
registered. In addition to time stamping and saving the event, if it is of
one-second period and of consistently high accuracy, the local system clock
will automatically calibrate to it.
.RE

.SH FILES
.LP
Files in or under /\fBdev\fR
.SH SEE ALSO
.LP
\fBstty\fR(1), \fBfork\fR(2), \fBgetpgid\fR(2), \fBgetsid\fR(2),
\fBioctl\fR(2), \fBsetsid\fR(2), \fBsigaction\fR(2), \fBsignal\fR(3C),
\fBtcsetpgrp\fR(3C), \fBtermios\fR(3C), \fBsignal.h\fR(3HEAD),
\fBstreamio\fR(7I)