TCSENDBREAK(3) Library Functions Manual TCSENDBREAK(3)

tcdrain, tcflow, tcflush, tcsendbreak — line control functions

Standard C Library (libc, -lc)

#include <termios.h>

int
tcdrain(int fildes);

int
tcflow(int fildes, int action);

int
tcflush(int fildes, int action);

int
tcsendbreak(int fildes, int duration);

The () function waits until all output written to the terminal referenced by fildes has been transmitted to the terminal.

The () function suspends transmission of data to, or the reception of data from, the terminal referenced by fildes, 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 () function discards any data written to the terminal referenced by fildes 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 () function transmits a continuous stream of zero-valued bits for four-tenths of a second to the terminal referenced by fildes. The duration parameter is ignored in this implementation.

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

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

[]
The fildes argument is not a valid file descriptor.
[]
A signal interrupted the tcdrain() function.
[]
The action argument is not a proper value.
[]
The file associated with fildes is not a terminal.

tcsetattr(3), termios(4)

The tcsendbreak(), tcdrain(), tcflush() and tcflow() functions are expected to be compliant with the IEEE Std 1003.1-1988 (“POSIX.1”) specification.

June 4, 1993 macOS 15.2