tcflush(3) DG/UX 4.30 tcflush(3)
NAME
tcsendbreak, tcdrain, tcflush, tcflow - Line control
functions.
FUNCTIONS
tcsendbreak(), tcdrain(), tcflush(), tcflow()
SYNOPSIS
#include <termios.h>
int tcsendbreak (fildes, duration)
int fildes;
int duration;
int tcdrain (fildes)
int fildes;
int tcflush (fildes, queue_selector)
int fildes;
int queue_selector;
int tcflow (fildes, action)
int fildes;
int action;
DESCRIPTION
If the terminal is using asynchronous serial data
transmission, the tcsendbreak() function shall cause
transmission of a continuous stream of zero-valued bits for
a specific duration. If duration is zero, it shall cause
transmission of zero-valued bits for at least 0.25 seconds,
and not more that 0.5 seconds. If duration is not zero, it
shall send zero-valued bits for an implementation-defined
period of time.
If the terminal is not using asynchronous serial data
transmission, it is implementation-defined whether the
tcsendbreak() function sends data to generate a break
condition (as defined by the implementation) or returns
without taking any action.
The tcdrain() function shall wait until all output written
to the object referred to by fildes has been transmitted.
The tcflush() function shall discard data written to the
object referred to by fildes but not transmitted, or data
received but not read, depending on the value of
queue_selector:
(1) If queue_selector is TCIFLUSH, it shall flush data
received but not read.
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tcflush(3) DG/UX 4.30 tcflush(3)
(2) If queue_selector is TCOFLUSH, it shall flush data
written but not transmitted.
(3) If queue_selector is TCIOFLUSH, it shall flush both
data received but not read, and data written but not
transmitted.
The tcflow() function shall suspend transmission or
reception of data on the object referred to by fildes,
depending on the value of action:
(1) If action is TCOOFF, it shall suspend output.
(2) If action is TCOON, it shall restart suspended
output.
(3) If action is TCIOFF, the system shall transmit a
STOP character, which is intended to cause the terminal
device to stop transmitting data to the system.
(4) If action is TCION, the system shall transmit a
START character, which is intended to cause the
terminal device to start transmitting data to the
system.
The symbolic constants for the values of queue_selector and
action are defined in <termios.h>.
The default on open of a terminal file is that neither its
input nor its output is suspended.
RETURNS
Upon successful completion, a value of zero is returned.
Otherwise, a value of -1 is returned and errno is set to
indicate the error.
ERRORS
If any of the following conditions occur, the tcsendbreak()
function shall return -1 and set errno to the corresponding
value:
[EBADF]
The fildes argument is not a valid file descriptor.
[ENOTTY]
The file associated with fildes is not a terminal.
If any of the following conditions occur, the tcdrain()
function shall return -1 and set errno to the corresponding
value:
[EBADF]
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tcflush(3) DG/UX 4.30 tcflush(3)
The fildes argument is not a valid file descriptor.
[EINTR]
A signal interrupted the tcdrain() function.
[ENOTTY]
The file associated with fildes is not a terminal.
If any of the following conditions occur, the tcflush()
function shall return -1 and set errno to the corresponding
value:
[EBADF]
The fildes argument is not a valid file descriptor.
[EINVAL]
The queue_selector argument is not a proper value.
[ENOTTY]
The file associated with fildes is not a terminal.
If any of the following conditions occur, the tcflow()
function shall return -1 and set errno to the corresponding
value:
[EBADF]
The fildes argument is not a valid file descriptor.
[EINVAL]
The action argument is not a proper value.
[ENOTTY]
The file associated with fildes is not a terminal.
SEE ALSO
<termios.h>
COPYRIGHTS
Portions of this text are reprinted from IEEE Std 1003.1-
1988, Portable Operating System Interface for Computer
Environment, copyright © 1988 by the Institute of Electrical
and Electronics Engineers, Inc., with the permission of the
IEEE Standards Department. To purchase IEEE Standards, call
800/678-IEEE.
In the event of a discrepancy between the electronic and the
original printed version, the original version takes
precedence.
STANDARDS
If the duration argument to the tcsendbreak() function is
not zero, the function will send zero-valued bits for
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tcflush(3) DG/UX 4.30 tcflush(3)
duration microseconds.
When tcsendbreak() is invoked on a pseudo-terminal device
file, no data will be sent unless the pseudo-terminal is in
packet mode. See pty(7) for details.
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