termios

TERMIOS(3)                  Linux Programmer's Manual                 TERMIOS(3)



NAME
       termios, tcgetattr, tcsetattr, tcsendbreak, tcdrain, tcflush, tcflow,
       cfmakeraw, cfgetospeed, cfgetispeed, cfsetispeed, cfsetospeed, cfsetspeed
       - get and set terminal attributes, line control, get and set baud rate

SYNOPSIS
       #include <termios.h>
       #include <unistd.h>

       int tcgetattr(int fd, struct termios *termios_p);
       int tcsetattr(int fd, int optional_actions,
                     const struct termios *termios_p);

       int tcsendbreak(int fd, int duration);
       int tcdrain(int fd);
       int tcflush(int fd, int queue_selector);
       int tcflow(int fd, int action);

       void cfmakeraw(struct termios *termios_p);

       speed_t cfgetispeed(const struct termios *termios_p);
       speed_t cfgetospeed(const struct termios *termios_p);

       int cfsetispeed(struct termios *termios_p, speed_t speed);
       int cfsetospeed(struct termios *termios_p, speed_t speed);
       int cfsetspeed(struct termios *termios_p, speed_t speed);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       cfsetspeed(), cfmakeraw():
           Since glibc 2.19:
               _DEFAULT_SOURCE
           Glibc 2.19 and earlier:
               _BSD_SOURCE

DESCRIPTION
       The termios functions describe a general terminal interface that is
       provided to control asynchronous communications ports.

   The termios structure
       Many of the functions described here have a termios_p argument that is a
       pointer to a termios structure.  This structure contains at least the
       following members:

           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];   /* special characters */

       The values that may be assigned to these fields are described below.  In
       the case of the first four bit-mask fields, the definitions of some of
       the associated flags that may be set are exposed only if a specific
       feature test macro (see feature_test_macros(7)) is defined, as noted in
       brackets ("[]").

       In the descriptions below, "not in POSIX" means that the value is not
       specified in POSIX.1-2001, and "XSI" means that the value is specified in
       POSIX.1-2001 as part of the XSI extension.

       c_iflag flag constants:

       IGNBRK Ignore BREAK condition on input.

       BRKINT If IGNBRK is set, a BREAK is ignored.  If it is not set but BRKINT
              is set, then a BREAK causes the input and output queues to be
              flushed, and if the terminal is the controlling terminal of a
              foreground process group, it will cause a SIGINT to be sent to
              this foreground process group.  When neither IGNBRK nor BRKINT are
              set, a BREAK reads as a null byte ('\0'), except when PARMRK is
              set, in which case it reads as the sequence \377 \0 \0.

       IGNPAR Ignore framing errors and parity errors.

       PARMRK If this bit is set, input bytes with parity or framing errors are
              marked when passed to the program.  This bit is meaningful only
              when INPCK is set and IGNPAR is not set.  The way erroneous bytes
              are marked is with two preceding bytes, \377 and \0.  Thus, the
              program actually reads three bytes for one erroneous byte received
              from the terminal.  If a valid byte has the value \377, and ISTRIP
              (see below) is not set, the program might confuse it with the
              prefix that marks a parity error.  Therefore, a valid byte \377 is
              passed to the program as two bytes, \377 \377, in this case.

              If neither IGNPAR nor PARMRK is set, read a character with a
              parity error or framing error as \0.

       INPCK  Enable input parity checking.

       ISTRIP Strip off eighth bit.

       INLCR  Translate NL to CR on input.

       IGNCR  Ignore carriage return on input.

       ICRNL  Translate carriage return to newline on input (unless IGNCR is
              set).

       IUCLC  (not in POSIX) Map uppercase characters to lowercase on input.

       IXON   Enable XON/XOFF flow control on output.

       IXANY  (XSI) Typing any character will restart stopped output.  (The
              default is to allow just the START character to restart output.)

       IXOFF  Enable XON/XOFF flow control on input.

       IMAXBEL
              (not in POSIX) Ring bell when input queue is full.  Linux does not
              implement this bit, and acts as if it is always set.

       IUTF8 (since Linux 2.6.4)
              (not in POSIX) Input is UTF8; this allows character-erase to be
              correctly performed in cooked mode.

       c_oflag flag constants:

       OPOST  Enable implementation-defined output processing.

       OLCUC  (not in POSIX) Map lowercase characters to uppercase on output.

       ONLCR  (XSI) Map NL to CR-NL on output.

       OCRNL  Map CR to NL on output.

       ONOCR  Don't output CR at column 0.

       ONLRET Don't output CR.

       OFILL  Send fill characters for a delay, rather than using a timed delay.

       OFDEL  Fill character is ASCII DEL (0177).  If unset, fill character is
              ASCII NUL ('\0').  (Not implemented on Linux.)

       NLDLY  Newline delay mask.  Values are NL0 and NL1.  [requires
              _BSD_SOURCE or _SVID_SOURCE or _XOPEN_SOURCE]

       CRDLY  Carriage return delay mask.  Values are CR0, CR1, CR2, or CR3.
              [requires _BSD_SOURCE or _SVID_SOURCE or _XOPEN_SOURCE]

       TABDLY Horizontal tab delay mask.  Values are TAB0, TAB1, TAB2, TAB3 (or
              XTABS, but see the BUGS section).  A value of TAB3, that is,
              XTABS, expands tabs to spaces (with tab stops every eight
              columns).  [requires _BSD_SOURCE or _SVID_SOURCE or _XOPEN_SOURCE]

       BSDLY  Backspace delay mask.  Values are BS0 or BS1.  (Has never been
              implemented.)  [requires _BSD_SOURCE or _SVID_SOURCE or
              _XOPEN_SOURCE]

       VTDLY  Vertical tab delay mask.  Values are VT0 or VT1.

       FFDLY  Form feed delay mask.  Values are FF0 or FF1.  [requires
              _BSD_SOURCE or _SVID_SOURCE or _XOPEN_SOURCE]

       c_cflag flag constants:

       CBAUD  (not in POSIX) Baud speed mask (4+1 bits).  [requires _BSD_SOURCE
              or _SVID_SOURCE]

       CBAUDEX
              (not in POSIX) Extra baud speed mask (1 bit), included in CBAUD.
              [requires _BSD_SOURCE or _SVID_SOURCE]

              (POSIX says that the baud speed is stored in the termios structure
              without specifying where precisely, and provides cfgetispeed() and
              cfsetispeed() for getting at it.  Some systems use bits selected
              by CBAUD in c_cflag, other systems use separate fields, for
              example, sg_ispeed and sg_ospeed.)

       CSIZE  Character size mask.  Values are CS5, CS6, CS7, or CS8.

       CSTOPB Set two stop bits, rather than one.

       CREAD  Enable receiver.

       PARENB Enable parity generation on output and parity checking for input.

       PARODD If set, then parity for input and output is odd; otherwise even
              parity is used.

       HUPCL  Lower modem control lines after last process closes the device
              (hang up).

       CLOCAL Ignore modem control lines.

       LOBLK  (not in POSIX) Block output from a noncurrent shell layer.  For
              use by shl (shell layers).  (Not implemented on Linux.)

       CIBAUD (not in POSIX) Mask for input speeds.  The values for the CIBAUD
              bits are the same as the values for the CBAUD bits, shifted left
              IBSHIFT bits.  [requires _BSD_SOURCE or _SVID_SOURCE] (Not
              implemented on Linux.)

       CMSPAR (not in POSIX) Use "stick" (mark/space) parity (supported on
              certain serial devices): if PARODD is set, the parity bit is
              always 1; if PARODD is not set, then the parity bit is always 0.
              [requires _BSD_SOURCE or _SVID_SOURCE]

       CRTSCTS
              (not in POSIX) Enable RTS/CTS (hardware) flow control.  [requires
              _BSD_SOURCE or _SVID_SOURCE]

       c_lflag flag constants:

       ISIG   When any of the characters INTR, QUIT, SUSP, or DSUSP are
              received, generate the corresponding signal.

       ICANON Enable canonical mode (described below).

       XCASE  (not in POSIX; not supported under Linux) If ICANON is also set,
              terminal is uppercase only.  Input is converted to lowercase,
              except for characters preceded by \.  On output, uppercase
              characters are preceded by \ and lowercase characters are
              converted to uppercase.  [requires _BSD_SOURCE or _SVID_SOURCE or
              _XOPEN_SOURCE]

       ECHO   Echo input characters.

       ECHOE  If ICANON is also set, the ERASE character erases the preceding
              input character, and WERASE erases the preceding word.

       ECHOK  If ICANON is also set, the KILL character erases the current line.

       ECHONL If ICANON is also set, echo the NL character even if ECHO is not
              set.

       ECHOCTL
              (not in POSIX) If ECHO is also set, terminal special characters
              other than TAB, NL, START, and STOP are echoed as ^X, where X is
              the character with ASCII code 0x40 greater than the special
              character.  For example, character 0x08 (BS) is echoed as ^H.
              [requires _BSD_SOURCE or _SVID_SOURCE]

       ECHOPRT
              (not in POSIX) If ICANON and ECHO are also set, characters are
              printed as they are being erased.  [requires _BSD_SOURCE or
              _SVID_SOURCE]

       ECHOKE (not in POSIX) If ICANON is also set, KILL is echoed by erasing
              each character on the line, as specified by ECHOE and ECHOPRT.
              [requires _BSD_SOURCE or _SVID_SOURCE]

       DEFECHO
              (not in POSIX) Echo only when a process is reading.  (Not
              implemented on Linux.)

       FLUSHO (not in POSIX; not supported under Linux) Output is being flushed.
              This flag is toggled by typing the DISCARD character.  [requires
              _BSD_SOURCE or _SVID_SOURCE]

       NOFLSH Disable flushing the input and output queues when generating
              signals for the INT, QUIT, and SUSP characters.

       TOSTOP Send the SIGTTOU signal to the process group of a background
              process which tries to write to its controlling terminal.

       PENDIN (not in POSIX; not supported under Linux) All characters in the
              input queue are reprinted when the next character is read.
              (bash(1) handles typeahead this way.)  [requires _BSD_SOURCE or
              _SVID_SOURCE]

       IEXTEN Enable implementation-defined input processing.  This flag, as
              well as ICANON must be enabled for the special characters EOL2,
              LNEXT, REPRINT, WERASE to be interpreted, and for the IUCLC flag
              to be effective.

       The c_cc array defines the terminal special characters.  The symbolic
       indices (initial values) and meaning are:

       VDISCARD
              (not in POSIX; not supported under Linux; 017, SI, Ctrl-O) Toggle:
              start/stop discarding pending output.  Recognized when IEXTEN is
              set, and then not passed as input.

       VDSUSP (not in POSIX; not supported under Linux; 031, EM, Ctrl-Y) Delayed
              suspend character (DSUSP): send SIGTSTP signal when the character
              is read by the user program.  Recognized when IEXTEN and ISIG are
              set, and the system supports job control, and then not passed as
              input.

       VEOF   (004, EOT, Ctrl-D) End-of-file character (EOF).  More precisely:
              this character causes the pending tty buffer to be sent to the
              waiting user program without waiting for end-of-line.  If it is
              the first character of the line, the read(2) in the user program
              returns 0, which signifies end-of-file.  Recognized when ICANON is
              set, and then not passed as input.

       VEOL   (0, NUL) Additional end-of-line character (EOL).  Recognized when
              ICANON is set.

       VEOL2  (not in POSIX; 0, NUL) Yet another end-of-line character (EOL2).
              Recognized when ICANON is set.

       VERASE (0177, DEL, rubout, or 010, BS, Ctrl-H, or also #) Erase character
              (ERASE).  This erases the previous not-yet-erased character, but
              does not erase past EOF or beginning-of-line.  Recognized when
              ICANON is set, and then not passed as input.

       VINTR  (003, ETX, Ctrl-C, or also 0177, DEL, rubout) Interrupt character
              (INTR).  Send a SIGINT signal.  Recognized when ISIG is set, and
              then not passed as input.

       VKILL  (025, NAK, Ctrl-U, or Ctrl-X, or also @) Kill character (KILL).
              This erases the input since the last EOF or beginning-of-line.
              Recognized when ICANON is set, and then not passed as input.

       VLNEXT (not in POSIX; 026, SYN, Ctrl-V) Literal next (LNEXT).  Quotes the
              next input character, depriving it of a possible special meaning.
              Recognized when IEXTEN is set, and then not passed as input.

       VMIN   Minimum number of characters for noncanonical read (MIN).

       VQUIT  (034, FS, Ctrl-\) Quit character (QUIT).  Send SIGQUIT signal.
              Recognized when ISIG is set, and then not passed as input.

       VREPRINT
              (not in POSIX; 022, DC2, Ctrl-R) Reprint unread characters
              (REPRINT).  Recognized when ICANON and IEXTEN are set, and then
              not passed as input.

       VSTART (021, DC1, Ctrl-Q) Start character (START).  Restarts output
              stopped by the Stop character.  Recognized when IXON is set, and
              then not passed as input.

       VSTATUS
              (not in POSIX; not supported under Linux; status request: 024,
              DC4, Ctrl-T).  Status character (STATUS).  Display status
              information at terminal, including state of foreground process and
              amount of CPU time it has consumed.  Also sends a SIGINFO signal
              (not supported on Linux) to the foreground process group.

       VSTOP  (023, DC3, Ctrl-S) Stop character (STOP).  Stop output until Start
              character typed.  Recognized when IXON is set, and then not passed
              as input.

       VSUSP  (032, SUB, Ctrl-Z) Suspend character (SUSP).  Send SIGTSTP signal.
              Recognized when ISIG is set, and then not passed as input.

       VSWTCH (not in POSIX; not supported under Linux; 0, NUL) Switch character
              (SWTCH).  Used in System V to switch shells in shell layers, a
              predecessor to shell job control.

       VTIME  Timeout in deciseconds for noncanonical read (TIME).

       VWERASE
              (not in POSIX; 027, ETB, Ctrl-W) Word erase (WERASE).  Recognized
              when ICANON and IEXTEN are set, and then not passed as input.

       An individual terminal special character can be disabled by setting the
       value of the corresponding c_cc element to _POSIX_VDISABLE.

       The above symbolic subscript values are all different, except that VTIME,
       VMIN may have the same value as VEOL, VEOF, respectively.  In
       noncanonical mode the special character meaning is replaced by the
       timeout meaning.  For an explanation of VMIN and VTIME, see the
       description of noncanonical mode below.

   Retrieving and changing terminal settings
       tcgetattr() gets the parameters associated with the object referred by fd
       and stores them in the termios structure referenced by termios_p.  This
       function may be invoked from a background process; however, the terminal
       attributes may be subsequently changed by a foreground process.

       tcsetattr() sets the parameters associated with the terminal (unless
       support is required from the underlying hardware that is not available)
       from the termios structure referred to by termios_p.  optional_actions
       specifies when the changes take effect:

       TCSANOW
              the change occurs immediately.

       TCSADRAIN
              the change occurs after all output written to fd has been
              transmitted.  This option should be used when changing parameters
              that affect output.

       TCSAFLUSH
              the change occurs after all output written to the object referred
              by fd has been transmitted, and all input that has been received
              but not read will be discarded before the change is made.

   Canonical and noncanonical mode
       The setting of the ICANON canon flag in c_lflag determines whether the
       terminal is operating in canonical mode (ICANON set) or noncanonical mode
       (ICANON unset).  By default, ICANON is set.

       In canonical mode:

       * Input is made available line by line.  An input line is available when
         one of the line delimiters is typed (NL, EOL, EOL2; or EOF at the start
         of line).  Except in the case of EOF, the line delimiter is included in
         the buffer returned by read(2).

       * Line editing is enabled (ERASE, KILL; and if the IEXTEN flag is set:
         WERASE, REPRINT, LNEXT).  A read(2) returns at most one line of input;
         if the read(2) requested fewer bytes than are available in the current
         line of input, then only as many bytes as requested are read, and the
         remaining characters will be available for a future read(2).

       * The maximum line length is 4096 chars (including the terminating
         newline character); lines longer than 4096 chars are truncated.  After
         4095 characters, input processing (e.g., ISIG and ECHO* processing)
         continues, but any input data after 4095 characters up to (but not
         including) any terminating newline is discarded.  This ensures that the
         terminal can always receive more input until at least one line can be
         read.

       In noncanonical mode input is available immediately (without the user
       having to type a line-delimiter character), no input processing is
       performed, and line editing is disabled.  The read buffer will only
       accept 4095 chars; this provides the necessary space for a newline char
       if the input mode is switched to canonical.  The settings of MIN
       (c_cc[VMIN]) and TIME (c_cc[VTIME]) determine the circumstances in which
       a read(2) completes; there are four distinct cases:

       MIN == 0, TIME == 0 (polling read)
              If data is available, read(2) returns immediately, with the lesser
              of the number of bytes available, or the number of bytes
              requested.  If no data is available, read(2) returns 0.

       MIN > 0, TIME == 0 (blocking read)
              read(2) blocks until MIN bytes are available, and returns up to
              the number of bytes requested.

       MIN == 0, TIME > 0 (read with timeout)
              TIME specifies the limit for a timer in tenths of a second.  The
              timer is started when read(2) is called.  read(2) returns either
              when at least one byte of data is available, or when the timer
              expires.  If the timer expires without any input becoming
              available, read(2) returns 0.  If data is already available at the
              time of the call to read(2), the call behaves as though the data
              was received immediately after the call.

       MIN > 0, TIME > 0 (read with interbyte timeout)
              TIME specifies the limit for a timer in tenths of a second.  Once
              an initial byte of input becomes available, the timer is restarted
              after each further byte is received.  read(2) returns when any of
              the following conditions is met:

              *  MIN bytes have been received.

              *  The interbyte timer expires.

              *  The number of bytes requested by read(2) has been received.
                 (POSIX does not specify this termination condition, and on some
                 other implementations read(2) does not return in this case.)

              Because the timer is started only after the initial byte becomes
              available, at least one byte will be read.  If data is already
              available at the time of the call to read(2), the call behaves as
              though the data was received immediately after the call.

       POSIX does not specify whether the setting of the O_NONBLOCK file status
       flag takes precedence over the MIN and TIME settings.  If O_NONBLOCK is
       set, a read(2) in noncanonical mode may return immediately, regardless of
       the setting of MIN or TIME.  Furthermore, if no data is available, POSIX
       permits a read(2) in noncanonical mode to return either 0, or -1 with
       errno set to EAGAIN.

   Raw mode
       cfmakeraw() sets the terminal to something like the "raw" mode of the old
       Version 7 terminal driver: input is available character by character,
       echoing is disabled, and all special processing of terminal input and
       output characters is disabled.  The terminal attributes are set as
       follows:

           termios_p->c_iflag &= ~(IGNBRK | BRKINT | PARMRK | ISTRIP
                           | INLCR | IGNCR | ICRNL | IXON);
           termios_p->c_oflag &= ~OPOST;
           termios_p->c_lflag &= ~(ECHO | ECHONL | ICANON | ISIG | IEXTEN);
           termios_p->c_cflag &= ~(CSIZE | PARENB);
           termios_p->c_cflag |= CS8;

   Line control
       tcsendbreak() transmits a continuous stream of zero-valued bits for a
       specific duration, if the terminal is using asynchronous serial data
       transmission.  If duration is zero, it transmits zero-valued bits for at
       least 0.25 seconds, and not more than 0.5 seconds.  If duration is not
       zero, it sends zero-valued bits for some implementation-defined length of
       time.

       If the terminal is not using asynchronous serial data transmission,
       tcsendbreak() returns without taking any action.

       tcdrain() waits until all output written to the object referred to by fd
       has been transmitted.

       tcflush() discards data written to the object referred to by fd but not
       transmitted, or data received but not read, depending on the value of
       queue_selector:

       TCIFLUSH
              flushes data received but not read.

       TCOFLUSH
              flushes data written but not transmitted.

       TCIOFLUSH
              flushes both data received but not read, and data written but not
              transmitted.

       tcflow() suspends transmission or reception of data on the object
       referred to by fd, depending on the value of action:

       TCOOFF suspends output.

       TCOON  restarts suspended output.

       TCIOFF transmits a STOP character, which stops the terminal device from
              transmitting data to the system.

       TCION  transmits a START character, which starts the terminal device
              transmitting data to the system.

       The default on open of a terminal file is that neither its input nor its
       output is suspended.

   Line speed
       The baud rate functions are provided for getting and setting the values
       of the input and output baud rates in the termios structure.  The new
       values do not take effect until tcsetattr() is successfully called.

       Setting the speed to B0 instructs the modem to "hang up".  The actual bit
       rate corresponding to B38400 may be altered with setserial(8).

       The input and output baud rates are stored in the termios structure.

       cfgetospeed() returns the output baud rate stored in the termios
       structure pointed to by termios_p.

       cfsetospeed() sets the output baud rate stored in the termios structure
       pointed to by termios_p to speed, which must be one of these constants:

            B0
            B50
            B75
            B110
            B134
            B150
            B200
            B300
            B600
            B1200
            B1800
            B2400
            B4800
            B9600
            B19200
            B38400
            B57600
            B115200
            B230400
            B460800
            B500000
            B576000
            B921600
            B1000000
            B1152000
            B1500000
            B2000000

       These constants are additionally supported on the SPARC architecture:

            B76800
            B153600
            B307200
            B614400

       These constants are additionally supported on non-SPARC architectures:

            B2500000
            B3000000
            B3500000
            B4000000

       Due to differences between architectures, portable applications should
       check if a particular Bnnn constant is defined prior to using it.

       The zero baud rate, B0, is used to terminate the connection.  If B0 is
       specified, the modem control lines shall no longer be asserted.
       Normally, this will disconnect the line.  CBAUDEX is a mask for the
       speeds beyond those defined in POSIX.1 (57600 and above).  Thus, B57600 &
       CBAUDEX is nonzero.

       Setting the baud rate to a value other than those defined by Bnnn
       constants is possible via the TCSETS2 ioctl; see ioctl_tty(2).

       cfgetispeed() returns the input baud rate stored in the termios
       structure.

       cfsetispeed() sets the input baud rate stored in the termios structure to
       speed, which must be specified as one of the Bnnn constants listed above
       for cfsetospeed().  If the input baud rate is set to zero, the input baud
       rate will be equal to the output baud rate.

       cfsetspeed() is a 4.4BSD extension.  It takes the same arguments as
       cfsetispeed(), and sets both input and output speed.

RETURN VALUE
       cfgetispeed() returns the input baud rate stored in the termios
       structure.

       cfgetospeed() returns the output baud rate stored in the termios
       structure.

       All other functions return:

       0      on success.

       -1     on failure and set errno to indicate the error.

       Note that tcsetattr() returns success if any of the requested changes
       could be successfully carried out.  Therefore, when making multiple
       changes it may be necessary to follow this call with a further call to
       tcgetattr() to check that all changes have been performed successfully.

ATTRIBUTES
       For an explanation of the terms used in this section, see attributes(7).

       ┌──────────────────────────────────────────────┬───────────────┬─────────┐
       │Interface                                     Attribute     Value   │
       ├──────────────────────────────────────────────┼───────────────┼─────────┤
       │tcgetattr(), tcsetattr(), tcdrain(),          │ Thread safety │ MT-Safe │
       │tcflush(), tcflow(), tcsendbreak(),           │               │         │
       │cfmakeraw(), cfgetispeed(), cfgetospeed(),    │               │         │
       │cfsetispeed(), cfsetospeed(), cfsetspeed()    │               │         │
       └──────────────────────────────────────────────┴───────────────┴─────────┘

CONFORMING TO
       tcgetattr(), tcsetattr(), tcsendbreak(), tcdrain(), tcflush(), tcflow(),
       cfgetispeed(), cfgetospeed(), cfsetispeed(), and cfsetospeed() are
       specified in POSIX.1-2001.

       cfmakeraw() and cfsetspeed() are nonstandard, but available on the BSDs.

NOTES
       UNIX V7 and several later systems have a list of baud rates where after
       the values B0 through B9600 one finds the two constants EXTA, EXTB
       ("External A" and "External B").  Many systems extend the list with much
       higher baud rates.

       The effect of a nonzero duration with tcsendbreak() varies.  SunOS
       specifies a break of duration * N seconds, where N is at least 0.25, and
       not more than 0.5.  Linux, AIX, DU, Tru64 send a break of duration
       milliseconds.  FreeBSD and NetBSD and HP-UX and MacOS ignore the value of
       duration.  Under Solaris and UnixWare, tcsendbreak() with nonzero
       duration behaves like tcdrain().

BUGS
       On the Alpha architecture before Linux 4.16 (and glibc before 2.28), the
       XTABS value was different from TAB3 and it was ignored by the N_TTY line
       discipline code of the terminal driver as a result (because as it wasn't
       part of the TABDLY mask).

SEE ALSO
       reset(1), setterm(1), stty(1), tput(1), tset(1), tty(1),
       ioctl_console(2), ioctl_tty(2), setserial(8)

COLOPHON
       This page is part of release 5.13 of the Linux man-pages project.  A
       description of the project, information about reporting bugs, and the
       latest version of this page, can be found at
       https://www.kernel.org/doc/man-pages/.



Linux                              2021-08-27                         TERMIOS(3)