The Open Group Base Specifications Issue 8
IEEE Std 1003.1-2024
Copyright © 2001-2024 The IEEE and The Open Group

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:

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

XBD 11. General Terminal Interface , <termios.h>

CHANGE HISTORY

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

Issue 6

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

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

Issue 7

POSIX.1-2008, Technical Corrigendum 1, XSH/TC1-2008/0645 [79], XSH/TC1-2008/0646 [79], and XSH/TC1-2008/0647 [79] are applied.

End of informative text.

 

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