PROLOG

       This  manual  page  is part of the POSIX Programmer's Manual.  The Linux implementation of this interface
       may differ (consult the corresponding Linux manual page for details of Linux behavior), or the  interface
       may not be implemented on Linux.

NAME

       tcflush — flush non-transmitted output data, non-read input data, or both

SYNOPSIS

       #include <termios.h>

       int tcflush(int fildes, int queue_selector);

DESCRIPTION

       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 thread is blocking SIGTTOU signals or the process is ignoring SIGTTOU  signals,  the  process
       shall be allowed to perform the operation, and no signal is sent.

RETURN VALUE

       Upon  successful  completion,  0  shall  be  returned.  Otherwise,  -1 shall be returned and errno set to
       indicate the error.

ERRORS

       The tcflush() function shall fail if:

       EBADF  The fildes argument is not a valid file descriptor.

       EINVAL The queue_selector argument is not a supported value.

       EIO    The process group of the writing process is orphaned, the calling thread is not blocking  SIGTTOU,
              and the process is not ignoring SIGTTOU.

       ENOTTY The file associated with fildes is not a terminal.

       The following sections are informative.

EXAMPLES

       None.

APPLICATION USAGE

       None.

RATIONALE

       None.

FUTURE DIRECTIONS

       None.

SEE ALSO

       tcdrain()

       The Base Definitions volume of POSIX.1‐2017, Chapter 11, General Terminal Interface, <termios.h>

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1-2017, Standard
       for Information  Technology  --  Portable  Operating  System  Interface  (POSIX),  The  Open  Group  Base
       Specifications  Issue  7, 2018 Edition, Copyright (C) 2018 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 .

       Any typographical or formatting errors that appear in this page are most likely to have  been  introduced
       during   the   conversion  of  the  source  files  to  man  page  format.  To  report  such  errors,  see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .