tcflow man page

Prolog

This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

tcflow — suspend or restart the transmission or reception of data

Synopsis

#include <termios.h>

int tcflow(int fildes, int action);

Description

The tcflow() function shall suspend or restart 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.

*
If action is TCOOFF, output shall be suspended.
*
If action is TCOON, suspended output shall be restarted.
*
If action is TCIOFF and fildes refers to a terminal device, the system shall transmit a STOP character, which is intended to cause the terminal device to stop transmitting data to the system. If fildes is associated with a pseudo-terminal, the STOP character need not be transmitted.
*
If action is TCION and fildes refers to a terminal device, the system shall transmit a START character, which is intended to cause the terminal device to start transmitting data to the system. If fildes is associated with a pseudo-terminal, the START character need not be transmitted.

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, shall cause the process group to be sent a SIGTTOU signal. If the calling thread is blocking SIGTTOU signals or the process is ignoring SIGTTOU signals, the process shall be allowed to perform the operation, and no signal is sent.

Return Value

Upon successful completion, 0 shall be returned. Otherwise, -1 shall be returned and errno set to indicate the error.

Errors

The tcflow() function shall fail if:

EBADF
The fildes argument is not a valid file descriptor.
EINVAL
The action argument is not a supported value.
EIO
The process group of the writing process is orphaned, the calling thread is not blocking SIGTTOU, and the process is not ignoring SIGTTOU.
ENOTTY
The file associated with fildes is not a terminal.

The following sections are informative.

See Also

tcsendbreak()

The Base Definitions volume of POSIX.1‐2008, Chapter 11, General Terminal Interface, <termios.h>

Info

2013 IEEE/The Open Group POSIX Programmer's Manual