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
If queue_selector is TCIFLUSH, it shall flush data received
but not read.
If queue_selector is TCOFLUSH, it shall flush data written but
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.
Upon successful completion, 0 shall be returned. Otherwise, -1 shall
be returned and errno set to indicate the error.
The tcflush() function shall fail if:
The fildes argument is not a valid file descriptor.
The queue_selector argument is not a supported value.
The file associated with fildes is not a terminal.
The tcflush() function may fail if:
The process group of the writing process is orphaned, and the writing
process is not ignoring or blocking SIGTTOU.
The following sections are informative.
tcdrain() , the Base Definitions volume of IEEE Std 1003.1-2001,
Chapter 11, General Terminal Interface, <termios.h>, <unistd.h>
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