tcflush

tcflush

Flush Terminal Input or Output

Portability: POSIX.1 conforming

SYNOPSIS
DESCRIPTION
RETURN VALUE
EXAMPLE
RELATED FUNCTIONS

SYNOPSIS

#include <termios.h>

int tcflush(int fileDescriptor, int queue);

DESCRIPTION

tcflush is called by a process to flush all input that has received but not yet been read by a terminal, or all output written but not transmitted to the terminal. Flushed data are discarded and cannot be retrieved.

fileDescriptor

is a file discriptor that refers to a terminal device.

queue

is a symbolic constant that specifies which queue to flush. The values for queue are defined in <termios.h> and can be any of the following:

`TCIFLUSH`	flushes the input queue, which contains data that have been received but not yet read.
`TCOFLUSH`	flushes the output queue, which contains data that have been written but not yet transmitted.
`TCIOFLUSH`	flushes both the input and output queue.

RETURN VALUE

tcflush returns a 0 if successful and a -1 if unsuccessful. If tcflush is called from a background process with a file descriptor that refers to the controlling terminal for the process, a SIGTTOU signal may be generated. This will cause the function call to be unsuccessful, returning a -1 and setting errno to EINTR . If SIGTTOU is blocked, the function call proceeds normally.

EXAMPLE

The following example illustrates the use of tcflush to flush both the input and output queues of a terminal:

#include <sys/types.h>
#include <termios.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>


main()
{
   int ttyDevice = STDOUT_FILENO;

      /* Make sure file descriptor is for a TTY device.   */
   if ( ! isatty(ttyDevice) ) {
      printf("Not a TTY device.n");
      return(EXIT_FAILURE);
   }

      /* Flush both the input and output queues.          */
   else {
      if (tcflush(ttyDevice, TCIOFLUSH) == 0)
         printf("The input and output queues have been flushed.n");
      else
         perror("tcflush error");
   }
   return(EXIT_SUCCESS);
 }

RELATED FUNCTIONS

tcdrain , tcflow

Chapter Contents
Previous
Next
Top of Page