Technical Reference: Base Operating System and Extensions, Volume 2

tcflow Subroutine

Purpose

Performs flow control functions.

Library

Standard C Library (libc.a)

Syntax

#include <termios.h>

int tcflow( FileDescriptor, Action) int FileDescriptor; int Action;

Description

The tcflow subroutine suspends transmission or reception of data on the object referred to by the FileDescriptor parameter, depending on the value of the Action parameter.

Parameters

FileDescriptor

Specifies an open file descriptor.

Action

Specifies one of the following:

TCOOFF: Suspend output.
TCOON: Restart suspended output.
TCIOFF: Transmit a STOP character, which is intended to cause the terminal device to stop transmitting data to the system. See the description of IXOFF in the Input Modes section of the termios.h file.
TCION: Transmit a START character, which is intended to cause the terminal device to start transmitting data to the system. See the description of IXOFF in the Input Modes section of the termios.h file.

Return Values

Upon successful completion, a value of 0 is returned. Otherwise, a value of -1 is returned and the errno global variable is set to indicate the error.

Error Codes

The tcflow subroutine is unsuccessful if one of the following is true:

EBADF	The FileDescriptor parameter does not specify a valid file descriptor.
EINVAL	The Action parameter does not specify a proper value.
EIO	The process group of the writing process is orphaned, and the writing process does not ignore or block the SIGTTOU signal.
ENOTTY	The file associated with the FileDescriptor parameter is not a terminal.

Example

To restart output from a terminal device, enter:

rc = tcflow(stdout, TCION);

Related Information

The tcdrain (tcdrain Subroutine) subroutine, tcflush (tcflush Subroutine) subroutine, tcsendbreak (tcsendbreak Subroutine) subroutine.

The Input and Output Handling Programmer's Overview in AIX 5L Version 5.2 General Programming Concepts: Writing and Debugging Programs.