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 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
tcsetattr(3),
termios(4)
STANDARDS
The
tcsendbreak,
tcdrain,
tcflush and
tcflow functions are expected
to be compliant with the
IEEE Std 1003.1-1988
(“POSIX.1”) specification.