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TCSENDBREAK(3) FreeBSD Library Functions Manual TCSENDBREAK(3)
NAME
tcsendbreak, tcdrain, tcflush, tcflow - line control functions
LIBRARY
Standard C Library (libc, -lc)
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 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 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 argument is ignored in this implementation.
[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.
[EWOULDBLOCK] The configured timeout expired before the tcdrain()
function could write all buffered output.
SEE ALSO
tcsetattr(3), termios(4), tty(4), comcontrol(8)
STANDARDS
The tcsendbreak(), tcflush() and tcflow() functions are expected to be
compliant with the IEEE Std 1003.1-1988 ("POSIX.1") specification.
The tcdrain() function is expected to be compliant with IEEE Std
1003.1-1988 ("POSIX.1") when the drain wait value is set to zero with
comcontrol(8), or with ioctl(2) TIOCSDRAINWAIT, or with sysctl(8)
kern.tty_drainwait. A non-zero drain wait value can result in tcdrain()
returning EWOULDBLOCK without writing all output. The default value for
kern.tty_drainwait is 300 seconds.
FreeBSD 14.0-RELEASE-p6 January 11, 2017 FreeBSD 14.0-RELEASE-p6