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.
