tcflush()

Updated: April 19, 2023

Flush the input and/or output stream

Synopsis:

#include <termios.h>

int tcflush( int filedes, 
             int queue_selector );

Arguments:

filedes
A file descriptor that's associated with the data stream that you want to perform the operation on.
queue_selector
The stream or streams that you want to flush. At least the following values for queue_selector are defined in <termios.h>:
  • TCIFLUSH — discard all data that's received, but not yet read, on the device associated with filedes.
  • TCOFLUSH — discard all data that's written, but not yet transmitted, on the device associated with filedes.
  • TCIOFLUSH — discard all data that's written, but not yet transmitted, as well as all data that's received, but not yet read, on the device associated with filedes.

Library:

libc

Use the -l c option to qcc to link against this library. This library is usually included automatically.

Description:

The tcflush() function flushes the input stream, the output stream, or both, depending on the value of the argument queue_selector.

Returns:

0
Success.
-1
An error occurred (errno is set).

Errors:

EBADF
Invalid filedes argument.
EINVAL
Invalid queue_selector argument.
ENOSYS
The resource manager associated with filedes doesn't support this call.
ENOTTY
The argument filedes doesn't refer to a terminal device.

Examples:

#include <termios.h>
#include <fcntl.h>
#include <unistd.h>
#include <stdlib.h>

int main( void )
  {
    int filedes;

    filedes = open( "/dev/ser1", O_RDWR );

    /* Throw away all input data */
    tcflush( filedes, TCIFLUSH );

    close( filedes );
    return EXIT_SUCCESS;
  }

Classification:

POSIX 1003.1

Safety:  
Cancellation point No
Interrupt handler No
Signal handler Yes
Thread Yes