Provided by: manpages-dev_3.15-1_all bug

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(): _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];   /* control chars */

       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 only exposed 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 IGNPAR is not set, prefix a character with a parity error  or
              framing  error  with  \377  \0.  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 defined in POSIX.1:

       OPOST  Enable implementation-defined output processing.

       The remaining c_oflag  flag  constants  are  defined  in  POSIX.1-2001,
       unless marked otherwise.

       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  (not  in  POSIX)  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).  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 non-current 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, ASCII control signals other
              than TAB, NL, START, and STOP are echoed as ^X, where X  is  the
              character  with ASCII code 0x40 greater than the control signal.
              For example, character 0x08 (BS) is  echoed  as  ^H.   [requires
              _BSD_SOURCE or _SVID_SOURCE]

       ECHOPRT
              (not  in POSIX) If ICANON and IECHO 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 the
              SIGINT, SIGQUIT, and SIGSUSP signals.

       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 special control  characters.   The  symbolic
       indices (initial values) and meaning are:

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

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

       VERASE (0177, DEL, rubout,  or  010,  BS,  Ctrl-H,  or  also  #)  Erase
              character.   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.

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

       VEOF   (004,  EOT, Ctrl-D) End-of-file character.  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.

       VMIN   Minimum number of characters for non-canonical read.

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

       VTIME  Timeout in deciseconds for non-canonical read.

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

       VSWTCH (not in  POSIX;  not  supported  under  Linux;  0,  NUL)  Switch
              character.  (Used by shl only.)

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

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

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

       VDSUSP (not in POSIX; not  supported  under  Linux;  031,  EM,  Ctrl-Y)
              Delayed   suspend   character:  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.

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

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

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

       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.

       VSTATUS
              (not  in  POSIX; not supported under Linux; status request: 024,
              DC4, Ctrl-T).

       These symbolic subscript values are all different, except  that  VTIME,
       VMIN  may  have  the  same  value as VEOL, VEOF, respectively.  In non-
       canonical mode the special character meaning is replaced by the timeout
       meaning.   For an explanation of VMIN and VTIME, see the description of
       non-canonical 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  function  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 non-canonical mode
       The setting of the ICANON canon flag in c_lflag determines whether  the
       terminal  is  operating in canonical mode (ICANON set) or non-canonical
       mode (ICANON unset).  By default, ICANON 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).

       In non-canonical mode input is available immediately (without the  user
       having  to  type  a  line-delimiter  character),  and  line  editing is
       disabled.  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:  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: read(2) blocks until the lesser of MIN bytes or
         the number of bytes requested are available, and returns  the  lesser
         of these two values.

       * MIN == 0; TIME > 0: 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.

       * MIN  > 0; TIME > 0: 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
         either when the lesser of the number of bytes requested or  MIN  byte
         have  been read, or when the inter-byte timeout expires.  Because the
         timer is only started after the initial byte  becomes  available,  at
         least one byte will be read.

   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 that 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

       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 non-zero.

       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.

CONFORMING TO

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

       cfmakeraw() and cfsetspeed() are non-standard,  but  available  on  the
       BSDs.

NOTES

       Unix V7 and several later systems have a list of baud rates where after
       the fourteen values B0, ..., 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 non-zero 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  non-zero
       duration behaves like tcdrain().

SEE ALSO

       stty(1), console_ioctl(4), tty_ioctl(4), setserial(8)

COLOPHON

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       description of the project, and information about reporting  bugs,  can
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