Upon successful completion, tcflush() shall discard data written to the
object referred to by fildes (an open file descriptor associated with a
terminal) but not transmitted, or data received but not read, depending on the
value of queue_selector:
If queue_selector is TCIFLUSH, it shall flush data
received but not read.
If queue_selector is TCOFLUSH, it shall flush data
written but not transmitted.
If queue_selector is TCIOFLUSH, it shall flush both
data received but not read and data written but not transmitted.
Attempts to use tcflush() from a process which is a member of a
background process group on a fildes associated with its controlling
terminal shall cause the process group to be sent a SIGTTOU signal. If the
calling process is blocking or ignoring SIGTTOU signals, the process shall be
allowed to perform the operation, and no signal is sent.
Portions of this text are reprinted and reproduced in electronic form from IEEE
Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable
Operating System Interface (POSIX), The Open Group Base Specifications Issue
6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. In the event of any discrepancy between
this version and the original IEEE and The Open Group Standard, the original
IEEE and The Open Group Standard is the referee document. The original
Standard can be obtained online at http://www.opengroup.org/unix/online.html