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.
tcflush — flush non-transmitted output data, non-read input data, or both
int tcflush(int fildes, int queue_selector);
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.
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.
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:
- If queue_selector is TCIOFLUSH, it shall flush both data received but not read and data written but not transmitted.
- The fildes argument is not a valid file descriptor.
- The queue_selector argument is not a supported value.
- The process group of the writing process is orphaned, the calling thread is not blocking SIGTTOU, and the process is not ignoring SIGTTOU.
The following sections are informative.
The Base Definitions volume of POSIX.1‐2008, Chapter 11, General Terminal Interface, <termios.h>
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 7, Copyright (C) 2013 by the Institute of Electrical and Electronics Engineers, Inc and The Open Group. (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) 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.unix.org/online.html .
- The file associated with fildes is not a terminal.
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