TCSENDBREAK(3)            OpenBSD Programmer's Manual           TCSENDBREAK(3)

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



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
     referenced 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 termi-
             nal to stop transmitting data to the system.  (See the descrip-
             tion of IXOFF in the `Input Modes' section of termios(4)).

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

     The tcflush() function discards any data written to the terminal refer-
     enced 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 parameter is ignored in this implementation.

RETURN VALUES
     Upon successful completion, all of these functions return a value of ze-
     ro.

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.

SEE ALSO
     tcsetattr(3),  termios(4)

STANDARDS
     The tcdrain(), tcflow(), tcflush(), and tcsendbreak() functions are ex-
     pected to be compliant with the IEEE Std1003.1-1988 (``POSIX'') specifi-
     cation.

OpenBSD 2.6                      March 4, 1992                               2