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TCSENDBREAK(3)		     Library Functions Manual		  TCSENDBREAK(3)

NAME
     tcsendbreak, tcdrain, tcflush, tcflow -- line control functions

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <termios.h>

     int
     tcdrain(int fd);

     int
     tcflow(int fd, int action);

     int
     tcflush(int fd, int action);

     int
     tcsendbreak(int fd, int len);

DESCRIPTION
     The  tcdrain() function waits until all output written to the terminal ref-
     erenced by fd has been transmitted to the terminal.

     The tcflow() function suspends transmission of data to or the reception  of
     data  from  the terminal referenced by fd depending on the value of action.
     The value of action must be one of the following:

     TCOOFF  Suspend output.

     TCOON   Restart suspended output.

     TCIOFF  Transmit a STOP character, which is intended to cause the	terminal
	     to  stop  transmitting data to the system.  (See the description of
	     IXOFF in the `Input Modes' section of termios(4)).

     TCION   Transmit a START character, which is intended to cause the terminal
	     to start transmitting data to the system.	(See the description  of
	     IXOFF in the `Input Modes' section of termios(4)).

     The tcflush() function discards any data written to the terminal referenced
     by  fd which has not been transmitted to the terminal, or any data received
     from the terminal but not yet read, depending on the value of action.   The
     value of action must be one of the following:

     TCIFLUSH	Flush data received but not read.

     TCOFLUSH	Flush data written but not transmitted.

     TCIOFLUSH	Flush  both  data received but not read and data written but not
		transmitted.

     The tcsendbreak() function transmits a  continuous  stream  of  zero-valued
     bits for four-tenths of a second to the terminal referenced by fd.  The len
     argument is ignored in this implementation.

RETURN VALUES
     Upon successful completion, all of these functions return a value of zero.

ERRORS
     If  any  error  occurs,  a  value of -1 is returned and the global variable
     errno is set to indicate the error, as follows:

     [EBADF]		The fd argument is not a valid file descriptor.

     [EINVAL]		The action argument is not a proper value.

     [ENOTTY]		The file associated with fd is not a terminal.

     [EINTR]		A signal interrupted the tcdrain() function.

     [EWOULDBLOCK]	The configured	timeout  expired  before  the  tcdrain()
			function could write all buffered output.

SEE ALSO
     tcsetattr(3), termios(4), tty(4), comcontrol(8)

STANDARDS
     The tcsendbreak(), tcflush() and tcflow() functions are expected to be com-
     pliant with the IEEE Std 1003.1-1988 ("POSIX.1") specification.

     The   tcdrain()  function	is  expected  to  be  compliant  with  IEEE  Std
     1003.1-1988 ("POSIX.1") when the drain wait value is set to zero with  com-
     control(8),   or	with   ioctl(2)   TIOCSDRAINWAIT,   or	 with  sysctl(8)
     kern.tty_drainwait.  A non-zero drain wait value can  result  in  tcdrain()
     returning	EWOULDBLOCK  without  writing all output.  The default value for
     kern.tty_drainwait is 300 seconds.

FreeBSD ports 15.1		January 11, 2017		  TCSENDBREAK(3)

Want to link to this manual page? Use this URL:
<https://man.freebsd.org/cgi/man.cgi?query=tcdrain&sektion=3&manpath=FreeBSD+15.1-RELEASE+and+Ports>

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