termios.4

早期freebsd实现

.Dv START
characters, which are
intended to cause the terminal device to resume transmitting data, as
soon as the device can continue transmitting data without risk of
overflowing the input queue.  The precise conditions under which
.Dv STOP
and
START
characters are transmitted are implementation defined.
.Pp
If
.Dv IMAXBEL
is set and the input queue is full, subsequent input shall cause an
.Tn ASCII
.Dv BEL
character to be transmitted to the
the output queue.
.Pp
The initial input control value after open() is implementation defined.
.Ss Output Modes
Values of the
.Fa c_oflag
field describe the basic terminal output control,
and are composed of the following masks:
.Pp
.Bl -tag -width OXTABS -offset indent -compact
.It Dv OPOST
/* enable following output processing */
.It Dv ONLCR
/* map NL to CR-NL (ala
.Dv CRMOD)
*/
.It Dv OXTABS
/* expand tabs to spaces */
.It Dv ONOEOT
/* discard
.Dv EOT Ns 's
.Ql \&^D
on output) */
.El
.Pp
If
.Dv OPOST
is set, the remaining flag masks are interpreted as follows;
otherwise characters are transmitted without change.
.Pp
If
.Dv ONLCR
is set, newlines are translated to carriage return, linefeeds.
.Pp
If
.Dv OXTABS
is set, tabs are expanded to the appropriate number of
spaces (assuming 8 column tab stops).
.Pp
If
.Dv ONOEOT
is set,
.Tn ASCII
.Dv EOT NS 's
are discarded on output.
.Ss Control Modes
Values of the
.Fa c_cflag
field describe the basic
terminal hardware control, and are composed of the
following masks.
Not all values
specified are supported by all hardware.
.Pp
.Bl -tag -width CRTSXIFLOW -offset indent -compact
.It Dv CSIZE
/* character size mask */
.It Dv CS5
/* 5 bits (pseudo) */
.It Dv CS6
/* 6 bits */
.It Dv CS7
/* 7 bits */
.It Dv CS8
/* 8 bits */
.It Dv CSTOPB
/* send 2 stop bits */
.It Dv CREAD
/* enable receiver */
.It Dv PARENB
/* parity enable */
.It Dv PARODD
/* odd parity, else even */
.It Dv HUPCL
/* hang up on last close */
.It Dv CLOCAL
/* ignore modem status lines */
.It Dv CCTS_OFLOW
/*
.Dv CTS
flow control of output */
.It Dv CRTSCTS
/* same as
.Dv CCTS_OFLOW
*/
.It Dv CRTS_IFLOW
/* RTS flow control of input */
.It Dv MDMBUF
/* flow control output via Carrier */
.El
.Pp
The
.Dv CSIZE
bits specify the byte size in bits for both transmission and
reception.  The
.Fa c_cflag
is masked with
.Dv CSIZE
and compared with the
values
.Dv CS5 ,
.Dv CS6 ,
.Dv CS7 ,
or
.Dv CS8 .
This size does not include the parity bit, if any.  If
.Dv CSTOPB
is set, two stop bits are used, otherwise one stop bit.  For example, at
110 baud, two stop bits are normally used.
.Pp
If
.Dv CREAD
is set, the receiver is enabled.  Otherwise, no character is
received. 
Not all hardware supports this bit.  In fact, this flag
is pretty silly and if it were not part of the
.Nm termios
specification
it would be omitted.
.Pp
If
.Dv PARENB
is set, parity generation and detection are enabled and a parity
bit is added to each character.  If parity is enabled,
.Dv PARODD
specifies
odd parity if set, otherwise even parity is used.
.Pp
If
.Dv HUPCL
is set, the modem control lines for the port are lowered
when the last process with the port open closes the port or the process
terminates.  The modem connection is broken.
.Pp
If
.Dv CLOCAL
is set, a connection does not depend on the state of the modem
status lines.  If
.Dv CLOCAL
is clear, the modem status lines are
monitored.
.Pp
Under normal circumstances, a call to the open() function waits for
the modem connection to complete.  However, if the
.Dv O_NONBLOCK
flag is set
or if
.Dv CLOCAL
has been set, the open() function returns
immediately without waiting for the connection.
.Pp
The
.Dv CCTS_OFLOW
.Pf ( Dv CRTSCTS )
flag is currently unused.
.Pp
If
.Dv MDMBUF
is set then output flow control is controlled by the state
of Carrier Detect.
.Pp
If the object for which the control modes are set is not an asynchronous
serial connection, some of the modes may be ignored; for example, if an
attempt is made to set the baud rate on a network connection to a
terminal on another host, the baud rate may or may not be set on the
connection between that terminal and the machine it is directly connected
to.
.Ss Local Modes
Values of the
.Fa c_lflag
field describe the control of
various functions, and are composed of the following
masks.
.Pp
.Bl -tag -width NOKERNINFO -offset indent -compact
.It Dv ECHOKE
/* visual erase for line kill */
.It Dv ECHOE
/* visually erase chars */
.It Dv ECHO
/* enable echoing */
.It Dv ECHONL
/* echo
.Dv NL
even if
.Dv ECHO
is off */
.It Dv ECHOPRT
/* visual erase mode for hardcopy */
.It Dv ECHOCTL
/* echo control chars as ^(Char) */
.It Dv ISIG
/* enable signals
.Dv INTR ,
.Dv QUIT ,
.Dv [D]SUSP
*/
.It Dv ICANON
/* canonicalize input lines */
.It Dv ALTWERASE
/* use alternate
.Dv WERASE
algorithm */
.It Dv IEXTEN
/* enable
.Dv DISCARD
and
.Dv LNEXT
*/
.It Dv EXTPROC
/* external processing */
.It Dv TOSTOP
/* stop background jobs from output */
.It Dv FLUSHO
/* output being flushed (state) */
.It Dv NOKERNINFO
/* no kernel output from
.Dv VSTATUS
*/
.It Dv PENDIN
/* XXX retype pending input (state) */
.It Dv NOFLSH
/* don't flush after interrupt */
.El
.Pp
If
.Dv ECHO
is set, input characters are echoed back to the terminal.  If
.Dv ECHO
is not set, input characters are not echoed.
.Pp
If
.Dv ECHOE
and
.Dv ICANON
are set, the
.Dv ERASE
character causes the terminal
to erase the last character in the current line from the display, if
possible.  If there is no character to erase, an implementation may echo
an indication that this was the case or do nothing.
.Pp
If
.Dv ECHOK
and
.Dv ICANON
are set, the
.Dv KILL
character causes
the current line to be discarded and the system echoes the
.Ql \&\en
character after the
.Dv KILL
character.
.Pp
If
.Dv ECHOKE
and
.Dv ICANON
are set, the
.Dv KILL
character causes
the current line to be discarded and the system causes
the terminal
to erase the line from the display.
.Pp
If
.Dv ECHOPRT
and
.Dv ICANON
are set, the system assumes
that the display is a printing device and prints a
backslash and the erased characters when processing
.Dv ERASE
characters, followed by a forward slash.
.Pp
If
.Dv ECHOCTL
is set, the system echoes control characters
in a visible fashion using a caret followed by the control character.
.Pp
If
.Dv ALTWERASE
is set, the system uses an alternative algorithm
for determining what constitutes a word when processing
.Dv WERASE
characters (see
.Dv WERASE ) .
.Pp
If
.Dv ECHONL
and
.Dv ICANON
are set, the
.Ql \&\en
character echoes even if
.Dv ECHO
is not set.
.Pp
If
.Dv ICANON
is set, canonical processing is enabled.  This enables the
erase and kill edit functions, and the assembly of input characters into
lines delimited by
.Dv NL,
.Dv EOF ,
and
.Dv EOL,
as described in
.Sx "Canonical Mode Input Processing" .
.Pp
If
.Dv ICANON
is not set, read requests are satisfied directly from the input
queue.  A read is not satisfied until at least
.Dv MIN
bytes have been
received or the timeout value
.Dv TIME
expired between bytes.  The time value
represents tenths of seconds.  See
.Sx "Noncanonical Mode Input Processing"
for more details.
.Pp
If
.Dv ISIG
is set, each input character is checked against the special
control characters
.Dv INTR ,
.Dv QUIT ,
and
.Dv SUSP
(job control only).  If an input
character matches one of these control characters, the function
associated with that character is performed.  If
.Dv ISIG
is not set, no
checking is done.  Thus these special input functions are possible only
if
.Dv ISIG
is set.
.Pp
If
.Dv IEXTEN
is set, implementation-defined functions are recognized
from the input data.  How
.Dv IEXTEN
being set
interacts with
.Dv ICANON ,
.Dv ISIG ,
.Dv IXON ,
or
.Dv IXOFF
is implementation defined.
If
.Dv IEXTEN
is not set, then
implementation-defined functions are not recognized, and the
corresponding input characters are not processed as described for
.Dv ICANON ,
.Dv ISIG ,
.Dv IXON ,
and
.Dv IXOFF .
.Pp
If
.Dv NOFLSH
is set, the normal flush of the input and output queues
associated with the
.Dv INTR ,
.Dv QUIT ,
and
.Dv SUSP
characters
are not be done.
.Pp
If
.Dv TOSTOP
is set, the signal
.Dv SIGTTOU
is sent to the process group of a process that tries to write to
its controlling terminal if it is not in the foreground process group for
that terminal.  This signal, by default, stops the members of the process
group.  Otherwise, the output generated by that process is output to the
current output stream.  Processes that are blocking or ignoring
.Dv SIGTTOU
signals are excepted and allowed to produce output and the
.Dv SIGTTOU
signal
is not sent.
.Pp
If
.Dv NOKERNINFO
is set, the kernel does not produce a status message
when processing
.Dv STATUS
characters (see
.Dv STATUS ) .
.Ss Special Control Characters
The special control characters values are defined by the array
.Fa c_cc .
This table lists the array index, the corresponding special character,
and the system default value.  For an accurate list of
the system defaults, consult the header file
.Aq Pa ttydefaults.h .
.Pp
.Bl -column "Index Name" "Special Character" -offset indent -compact
.It Em "Index Name	Special Character	Default Value"
.It Dv VEOF Ta EOF Ta \&^D
.It Dv VEOL Ta EOL Ta _POSIX_VDISABLE
.It Dv VEOL2 Ta EOL2 Ta _POSIX_VDISABLE
.It Dv VERASE Ta ERASE Ta \&^? Ql \&\e177
.It Dv VWERASE  Ta WERASE Ta \&^W
.It Dv VKILL Ta KILL Ta \&^U
.It Dv VREPRINT Ta REPRINT Ta \&^R
.It Dv VINTR Ta INTR Ta \&^C
.It Dv VQUIT Ta QUIT Ta \&^\e\e Ql \&\e34
.It Dv VSUSP Ta SUSP Ta \&^Z
.It Dv VDSUSP Ta DSUSP Ta \&^Y
.It Dv VSTART Ta START Ta \&^Q
.It Dv VSTOP Ta STOP Ta \&^S
.It Dv VLNEXT Ta LNEXT Ta \&^V
.It Dv VDISCARD Ta DISCARD Ta \&^O
.It Dv VMIN Ta --- Ta \&1
.It Dv VTIME Ta --- Ta \&0
.It Dv VSTATUS Ta STATUS Ta \&^T
.El
.Pp
If the
value of one of the changeable special control characters (see
.Sx "Special Characters" )
is
.Dv {_POSIX_VDISABLE} ,
that function is disabled; that is, no input
data is recognized as the disabled special character.
If
.Dv ICANON
is
not set, the value of
.Dv {_POSIX_VDISABLE}
has no special meaning for the
.Dv VMIN
and
.Dv VTIME
entries of the
.Fa c_cc
array.
.Pp
The initial values of the flags and control characters
after open() is set according to
the values in the header
.Aq Pa sys/ttydefaults.h .