NAME
tcdrain, tcflow,
tcflush, tcsendbreak
— line control
functions
SYNOPSIS
#include
<termios.h>
int
tcdrain(int
fd);
int
tcflow(int
fd, int
action);
int
tcflush(int
fd, int
action);
int
tcsendbreak(int
fd, int len);
DESCRIPTION
The
tcdrain()
function waits until all output written to the terminal referenced by
fd has been transmitted to the terminal.
The
tcflow()
function suspends transmission of data to or the reception of data from the
terminal referenced by fd 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
IXOFFin 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
fd 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 fd. The
len 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 fd argument is not a valid file descriptor.
- [
EINVAL] - The action argument is not a proper value.
- [
ENOTTY] - The file associated with fd is not a terminal.
- [
EINTR] - A signal interrupted the
tcdrain() function.
SEE ALSO
STANDARDS
The tcdrain(),
tcflow(), tcflush(), and
tcsendbreak() functions are expected to be compliant
with the IEEE Std 1003.1-1988
(“POSIX.1”) specification.