NAME
tcdrain, tcflow,
tcflush, tcsendbreak
— line control
functions
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include
<termios.h>
int
tcdrain(int fildes);
int
tcflow(int fildes,
int action);
int
tcflush(int fildes,
int action);
int
tcsendbreak(int fildes,
int duration);
DESCRIPTION
The
tcdrain()
function waits until all output written to the terminal referenced by
fildes has been transmitted to the terminal.
The
tcflow()
function suspends transmission of data to, or the reception of data from,
the terminal referenced by fildes, depending on the
value of action. The value of
action must be one of the following:
- TCOOFF
- Suspend output.
- TCOON
- Restart suspended output.
- TCIOFF
- Transmit a STOP character, which is intended to cause the terminal to stop
transmitting data to the system. (See the description of IXOFF in the
‘
Input Modes’ section of termios(4)). - TCION
- Transmit a START character, which is intended to cause the terminal to
start transmitting data to the system. (See the description of IXOFF in
the ‘
Input Modes’ section of termios(4)).
The
tcflush()
function discards any data written to the terminal referenced by
fildes which has not been transmitted to the terminal,
or any data received from the terminal but not yet read, depending on the
value of action. The value of
action must be one of the following:
- TCIFLUSH
- Flush data received but not read.
- TCOFLUSH
- Flush data written but not transmitted.
- TCIOFLUSH
- Flush both data received but not read and data written but not transmitted.
The
tcsendbreak()
function transmits a continuous stream of zero-valued bits for four-tenths
of a second to the terminal referenced by fildes. The
duration parameter is ignored in this
implementation.
RETURN VALUES
Upon successful completion, all of these functions return a value of zero.
ERRORS
If any error occurs, a value of -1 is returned and the global variable errno is set to indicate the error, as follows:
- [
EBADF] - The fildes argument is not a valid file descriptor.
- [
EINTR] - A signal interrupted the
tcdrain() function. - [
EINVAL] - The action argument is not a proper value.
- [
ENOTTY] - The file associated with fildes is not a terminal.
SEE ALSO
STANDARDS
The tcsendbreak(),
tcdrain(), tcflush() and
tcflow() functions are expected to be compliant with
the IEEE Std 1003.1-1988 (“POSIX.1”)
specification.