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 .