TCFLUSH(3) Library Functions Manual TCFLUSH(3)

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

#include <termios.h>

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.
  • 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 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.

None.

None.

None.

None.

tcdrain(3), the Base Definitions volume of IEEE Std 1003.1-2001 (“POSIX.1”), xbd_chap11(7), <termios.h>, <unistd.h>

First released in Issue 3. Included for alignment with the POSIX.1-1988 standard.

The Open Group Corrigendum U035/1 is applied. In the ERRORS and APPLICATION USAGE sections, references to tcflow(3) are replaced with tcflush ().

The following new requirements on POSIX implementations derive from alignment with the Single UNIX Specification:

  • In the DESCRIPTION, the final paragraph is no longer conditional on _POSIX_JOB_CONTROL. This is a FIPS requirement.
  • The [EIO] error is added.

footer end

December 6, 2001 posix.fail