TCFLOW(3C) Standard C Library Functions TCFLOW(3C)
NAME
tcflow - suspend or restart the transmission or reception of data
SYNOPSIS
#include <termios.h>
int tcflow(
int fildes,
int action);
DESCRIPTION
The
tcflow() function suspends transmission or reception of data on the
object referred to by
fildes, depending on the value of
action. The
fildes argument is an open file descriptor associated with a terminal.
o If
action is
TCOOFF, output is suspended.
o If
action is
TCOON, suspended output is restarted.
o If
action is
TCIOFF, the system transmits a
STOP character,
which is intended to cause the terminal device to stop
transmitting data to the system.
o If
action is
TCION, the system transmits a
START character,
which is intended to cause the terminal device to start
transmitting data to the system.
The default on the opening of a terminal file is that neither its input
nor its output are suspended.
Attempts to use
tcflow() from a process which is a member of a background
process group on a
fildes associated with its controlling terminal, will
cause the process group to be sent a
SIGTTOU signal. If the calling
process is blocking or ignoring
SIGTTOU signals, the process is allowed
to perform the operation, and no signal is sent.
RETURN VALUES
Upon successful completion,
0 is returned. Otherwise,
-1 is returned and
errno is set to indicate the error.
ERRORS
The
tcflow() function will fail if:
EBADF The
fildes argument is not a valid file descriptor.
EINVAL The
action argument is not a supported value.
ENOTTY The file associated with
fildes is not a terminal.
The
tcflow() function may fail if:
EIO The process group of the writing process is orphaned, and the
writing process is not ignoring or blocking
SIGTTOU.
ATTRIBUTES
See
attributes(7) for descriptions of the following attributes:
+--------------------+--------------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+--------------------------------+
|Interface Stability | Standard |
+--------------------+--------------------------------+
|MT-Level | MT-Safe, and Async-Signal-Safe |
+--------------------+--------------------------------+
SEE ALSO
tcsendbreak(3C),
termio(4I),
attributes(7),
standards(7) August 14, 2002
TCFLOW(3C)