termios, termios.h - Defines the structure of the termios
file, which provides the terminal interface for POSIX compatibility.
The /usr/include/termios.h header file is used to obtain
and modify attributes required by the terminal driver.
These attributes control input and output processing. The
definition values and structure in the
/usr/include/termios.h file are required for P1003.1 POSIX
compliance.
The primary mechanism for obtaining and setting terminal
driver parameters is through the following POSIX functions:
tcgetattr() tcsetattr() cfgetispeed() cfgetospeed()
cfsetospeed() cfsetispeed()
Optionally the termios values can be obtained or set using
the termios ioctls. See the tty(7) reference page. For
compatibility the system supports BSD and System V ioctls,
but they are internally translated into termios ioctls.
The termios structure in the <termios.h> header file contains
the following fields: Describes the basic terminal
input control. The possible input modes are: Ignores the
break condition. If set, the break condition is not put on
the input queue and is therefore not read by any process.
Interrupts signal on the break condition. If set, the
break condition generates an interrupt signal and flushes
both the input and output queues. Ignores characters with
parity errors. If set, characters with other framing and
parity errors are ignored. Marks parity errors. If set, a
character with a framing or parity error that is not
ignored is read as the 3-character sequence: 0377, 0, x,
where the x variable is the data of the character received
in error. If the ISTRIP mode is not set, then a valid
character of 0377 is read as 0377, 0377 to avoid ambiguity.
If the PARMRK mode is clear, a framing or parity
error that is not ignored is read as the null character.
Enables input parity checking. If set, input parity checking
is enabled. If clear, input parity checking is disabled.
This allows for output parity generation without
input parity errors. Strips characters. If set, valid
input characters are first stripped to 7 bits; otherwise
all 8 bits are processed. Maps new-line character (NL) to
carriage return (CR) on input. If set, a received NL character
is translated into a CR character. Ignores CR character.
If set, a received CR character is ignored (not
read). Maps CR character to NL character on input. If
set, a received CR character is translated into a NL character.
Maps uppercase to lowercase on input. If set, a
received uppercase, alphabetic character is translated
into the corresponding lowercase character. Enables start
and stop output control. If set, a received STOP character
suspends output, and a received START character restarts
output. The START and STOP characters perform flow control
functions but are not read. Enables any character to
restart output. If set, any input character restarts output
that was suspended. Enables start and stop input control.
If set, the system transmits a STOP character when
the input queue is nearly full and a START character when
enough input has been read that the queue is nearly empty
again. Echoes the ASCII BEL character if the input stream
overflows. Further input is not stored, but any input
received prior to the overflow condition is retained. If
clear, the BEL character is not echoed, and the input in
the input queue is discarded if the input stream overflows.
Specifies how the system treats output. The possible
output modes are: Postprocesses output. If set, output
characters are processed as indicated by the remaining
flags; otherwise, characters are transmitted without
change. Maps lowercase to uppercase on output. If set, a
lowercase alphabetic character is transmitted as the corresponding
uppercase character. This function is often
used in conjunction with the IUCLC input mode. Maps NL to
CR-NL on output. If set, the NL character is transmitted
as the CR-NL character pair. Maps CR to NL on output. If
set, the CR character is transmitted as the NL character.
Indicates no CR output at column 0. If set, no CR character
is transmitted at column 0 (first position). NL performs
CR function. If set, the NL character is assumed to
do the carriage return function. The column pointer is set
to a value of 0 and the delay specified for carriage
return is used. Otherwise the NL character is assumed to
do the line feed function only; the column pointer remains
unchanged. The column pointer is also set to a value of 0
if the CR character is actually transmitted.
The delay bits specify how long a transmission
stops to allow for mechanical or other movement
when certain characters are sent to the terminal.
The actual delays depend on line speed and system
load. Uses fill characters for delay. If set, fill
characters are transmitted for a delay instead of a
timed delay. This is useful for high baud rate terminals
that need only a minimal delay. Sets fill
characters to the DEL value. If set, the fill character
is DEL. If this flag is clear, the fill character
is null. Selects the newline character
delays. This is a mask to use before comparing to
NL0 and NL1. Specifies no delay. Specifies one
delay of approximately 0.10 seconds. If ONLRET is
set, the carriage return delays are used instead of
the newline delays. If OFILL is set, two fill characters
are transmitted. Selects the carriage
return delays. This is a mask to use before comparing
to CR0, CR1, CR2, and CR3. Specifies no delay.
Specifies that the delay is dependent on the current
column position. If OFILL is set, this delay
transmits two fill characters. Specifies one delay
of approximately 0.10 seconds. If OFILL is set,
this delay transmits four fill characters. Specifies
one delay of approximately 0.15 seconds.
Selects the horizontal tab delays. This is a mask
to use before comparing to TAB0, TAB1, TAB2, and
TAB3. If OFILL is set, any of these delays transmit
two fill characters. Specifies no delay. Specifies
that the delay is dependent on the current
column position. If OFILL is set, two fill characters
are transmitted. Specifies one delay of
approximately 0.10 seconds. Specifies that tabs
are to be expanded into spaces. Selects the
backspace delays. This is a mask to use before comparing
to BS0 and BS1. Specifies no delay. Specifies
one delay of approximately 0.05 seconds. If
OFILL is set, this delay transmits one fill character.
Selects the vertical-tab delays. This is a
mask to use before comparing to VT0 and VT1. Specifies
no delay. Specifies one delay of approximately
2 seconds. Selects the formfeed delays.
This is a mask to use before comparing to FF0 and
FF1. Specifies no delay. Specifies one delay of
approximately 2 seconds. Describes the hardware
control of the terminal. In addition to the basic
control modes, this field uses the following control
characters: Enables hardware flow control
using the Request to Sent (RTS) and Clear to Send
(CTS) signals. Specifies the character size. These
bits specify the character size in bits for both
transmit and receive operations. This size does
not include the parity bit, if any. 5 bits. 6
bits. 7 bits. 8 bits. Specifies number of stop
bits. If set, 2 stop bits are sent; otherwise, only
1 stop bit is sent. Higher baud rates require 2
stop bits. (At 110 baud, for example, 2 stop bits
are required.) Enables receiver. If set, the
receiver is enabled. Otherwise, characters are not
received. Enables parity. If set, parity generation
and detection is enabled and a parity bit is
added to each character. Specifies odd parity. If
parity is enabled, this specifies odd parity. If
clear, even parity is used. Hangs up on last
close. If set, the line is disconnected when the
last process closes the line or when the process
terminates (when the `data terminal ready' signal
drops). Specifies a local line. If set, the line
is assumed to have a local, direct connection with
no modem control. If clear, modem control (dialup)
is assumed. The initial hardware control value
after an open is CS8 and CREAD. Controls various
terminal functions. In addition to the basic modes,
this field uses the following mask name symbols:
Enables signals. If set, each input character is
checked against the INTR and QUIT special control
characters. If a character matches one of these
control characters, the function associated with
that character is performed. If the ISIG function
is clear, checking is not done. Enables canonical
input. If set, turns on canonical processing, which
enables the erase and kill edit functions as well
as the assembly of input characters into lines
delimited by NL, EOF, and EOL.
If the ICANON function is clear, read requests are
satisfied directly from the input queue. In this
case, a read request is not satisfied until one of
the following conditions is met: a) the minimum
number of characters specified by MIN are received;
or b) the timeout value specified by TIME has
expired since the last character was received. This
allows bursts of input to be read, while still
allowing single character input. The MIN and TIME
values are stored in the VMIN and VTIME positions,
respectively. The time value represents tenths of
seconds. Enables canonical uppercase and lowercase
presentation. If set along with the ICANON function,
an uppercase letter (or the uppercase letter
translated to lowercase by the IUCLC input mode) is
accepted on input by preceding it with a \ (backslash)
character. The output is then preceded by a
backslash character. Enables echo. If set, characters
are displayed on the terminal screen as they
are received. Echoes erase character as BS-SP-BS.
If the ECHO and ECHOE functions are both set and
ECHOPRT is clear, the erase character is implemented
as a backspace, a space, and then another
backspace (ASCII BS-SP-BS). This clears the last
character from the screen. If ECHOE is set, but
ECHO is clear, the erase character is implemented
as ASCII SP-BS. Echoes NL after kill. If ECHOK is
set and ECHOKE is clear, a newline function is performed
to clear the line after a KILL character is
received. This emphasizes that the line is deleted.
Note that an escape character preceding the ERASE
or KILL character removes any special function.
Echoes NL. If ECHONL is set, the line is cleared
when a newline function is performed whether or not
the ECHO function is set. This is useful for terminals
that are set to local echo (also referred to
as half-duplex). Unless an escape character precedes
an EOF, the EOF character is not displayed.
Because the ASCII EOT character is the default endof-file
character, this prevents terminals that
respond to the EOT character from hanging up. Disables
queue flushing. If set, the normal flushing
of the input and output queues associated with the
quit and interrupt characters is not done.
The ICANON, XCASE, ECHO, ECHOE, ECHOK, ECHONL, and
NOFLSH special input functions are possible only if
the ISIG function is set. These functions can be
disabled individually by changing the value of the
control character to an unlikely or impossible
value (for example, 0377 octal or 0xFF) Echoes control
characters as ^X, where the X variable is the
character given by adding 100 octal to the code of
the control character. The ASCII DEL character is
echoed as ^? and the ASCII TAB, NL, and START characters
are not echoed.
Unless an escape character precedes an EOF, the EOF
character is not displayed. Because the ASCII EOT
character is the default End-of-File character,
this mask prevents terminals that respond to the
EOT character from hanging up. Echoes the first
ERASE and WERASE character in a sequence as a \
(backslash), and then erases the characters. Subsequent
ERASE and WERASE characters echo the characters
being erased (in reverse order). Echoes the
kill character by erasing from the screen each
character on the line. Flushes the output. When
this bit is set by typing the FLUSH character, data
written to the terminal is discarded. A terminal
can cancel the effect of typing the FLUSH character
by clearing this bit. Reprints any input that has
not yet been read when the next character arrives
as input. Enables extended (implementationdefined)
functions to be recognized from the input
data. If this bit is clear, implementation-defined
functions are not recognized, and the corresponding
input characters are processed as described for
ICANON, ISIG, IXON, and IXOFF. Sends a SIGTTOU
signal when a process in a background process group
tries to write to its controlling terminal. The
SIGTTOU signal stops the members of the process
group. If job control is not supported, this symbol
is ignored. Specifies an array that defines the
special control characters. The relative positions
and initial values for each function are: Indexes
the INTR control character (Ctrl-Backspace), which
sends a SIGINT signal to stop all processes controlled
by this terminal. Indexes the QUIT control
character (Ctrl-v or Ctrl-|), which sends a SIGQUIT
signal to stop all processes controlled by this
terminal and writes a core image file into the current
working directory. Indexes the ERASE control
character (Backspace), which erases the preceding
character. The ERASE character does not erase
beyond the beginning of the line (delimited by a
NL, EOL, EOF, or EOL2 character). Indexes the KILL
control character (Ctrl-u), which deletes the
entire line (delimited by a NL, EOL, EOF, or EOL2
character). Indexes the EOF control character
(Ctrl-d), which can be used at the terminal to generate
an end-of-file. When this character is
received, all characters waiting to be read are
immediately passed to the program without waiting
for a new line, and the EOF is discarded. If the
EOF is at the beginning of a line (no characters
are waiting), zero characters are passed back,
which is the standard End-of-File. Indexes the EOL
control character (Ctrl-@ or ASCII null), which is
an additional line delimiter that is not normally
used. Indexes the EOL2 control character (Ctrl-@
or ASCII null), which is an additional line delimiter
that is not normally used. Indexes the START
control character (Ctrl-q), which resumes output
that has been suspended by a STOP character. START
characters are ignored if the output is not suspended.
Indexes the SUSP control character (Ctrlz),
which causes a SIGTSTP signal to be sent to all
foreground processes controlled by this terminal.
This character is recognized during input if the
ISIG flag is enabled. If job control is not supported,
this character is ignored. Indexes the
DSUSP control character (Ctrl-y), which causes a
SIGTSTP signal to be sent to all foreground processes
controlled by this terminal. This character
is recognized when the process attempts to read the
DSUSP character. If job control is not supported,
this character is ignored. Indexes the STOP control
character (Ctrl-s), which can be used to temporarily
suspend output. This character is recognized
during both input and output if the IXOFF
(input control) or IXON (output control) flag is
set. Indexes the REPRINT control character (Ctrlr),
which reprints all characters that are preceded
by a NL character and that have not been read.
Indexes the DISCARD control character (Ctrl-o),
which causes all output to be discarded until
another DISCARD character is typed, more input is
received, or the condition is cleared by a program.
Indexes the WERASE control character (Ctrl-w),
which erases the preceding word. The WERASE character
does not erase beyond the beginning of the line
(delimited by a NL, EOL, EOF, or EOL2 character).
Indexes the LNEXT (literal next) control character
(Ctrl-v), which causes the special meaning of the
next character to be ignored, so that characters
can be input without being interpreted by the system.
The character values for INTR, QUIT, SWTCH, ERASE,
KILL, EOF, and EOL can be changed. The ERASE, KILL,
and EOF characters can also be escaped (preceded
with a backslash) so that no special processing is
done. Indexes the minimum read value. This value
is used for noncanonical processing. See the previous
description of the ICANON flag. Indexes the
time value. This value is used for noncanonical
processing. See the previous description of the
ICANON flag. Specifies the input baud rate. The
default input baud rate is 9600. However, the
input baud rate can be specified to be one of the
following: Hangs up. The zero baud rate is used to
hang up the connection. If B0 is specified, the
`data terminal ready' signal is not asserted. Normally,
this disconnects the line. 50 baud. 75
baud. 110 baud. 134.5 baud. 150 baud. 200 baud.
300 baud. 600 baud. 600 baud. 1200 baud. 1800
baud. 2400 baud. 4800 baud. 9600 baud. 19200
baud. 38400 baud. 57600 baud. 115200 baud.
External A. External B. Specifies the output baud
rate.
The default output baud rate is 9600. However, the
possible output baud rate values are the same as
for the input baud rate values listed above.
The following values for the optional-actions parameter of
the tcsetattr() function are also defined in the termios.h
header file: Immediately sets the parameters associated
with the terminal from the referenced termios structure.
Waits until all output written to the object file has been
transmitted before setting the terminal parameters from
the termios structure. Waits until all output written to
the object file has been transmitted and all input
received but not read has been discarded before setting
the terminal parameters from the termios structure.
The following values for the queue-selector parameter of
the tcflush() function are also defined in this header
file: Flushes data that is received but not read. Flushes
data that is written but not transmitted. Flushes both
data that is received but not read and data that is written
but not transmitted.
The following values for the action parameter of the
tcflow() system call are also defined in the termios.h
header file: Suspends the output of data by the object
file named in the tcflow() function. Restarts data output
that was suspended by the TCOOFF parameter. Transmits a
stop character to stop data transmission by the terminal
device. Transmits a start character to start or restart
data transmission by the terminal device.
The path to the termios.h header file.
Files: ace(7), scc(7), tty(7)
Functions: ioctl(2), cfgetispeed(3), cfgetospeed(3),
cfsetispeed(3), cfsetospeed(3), tcsetattr(3), tcgetattr(3), tcflow(3), tcflush(3)
Commands: csh(1), sh(1), stty(1), tset(1), getty(8)
termios(4)
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