Writing data and output processing

When a process writes one or more bytes to a special file associated with a terminal, these bytes are processed according to the settings in c_oflag (see section “Output modes”). The system may provide a buffering mechanism, with the result that when a call to write() completes, all of the bytes written will have been scheduled for transmission to the device, but the transmission will not necessarily have completed. See write() for the effects of O_NONBLOCK on write().