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.TH TCFLOW "3P" 2013 "IEEE/The Open Group" "POSIX Programmer's Manual"

.SH 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.

.SH NAME

tcflow

\(em suspend or restart the transmission or reception of data

.SH SYNOPSIS

.LP

.nf

#include <termios.h>

.P

int tcflow(int \fIfildes\fP, int \fIaction\fP);

.fi

.SH DESCRIPTION

The

\fItcflow\fR()

function shall suspend or restart transmission or reception of data on

the object referred to by

.IR fildes ,

depending on the value of

.IR action .

The

.IR fildes

argument is an open file descriptor associated with a terminal.

.IP " *" 4

If

.IR action

is TCOOFF, output shall be suspended.

.IP " *" 4

If

.IR action

is TCOON, suspended output shall be restarted.

.IP " *" 4

If

.IR action

is TCIOFF and

.IR 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

.IR fildes

is associated with a pseudo-terminal, the STOP character need not be

transmitted.

.IP " *" 4

If

.IR action

is TCION and

.IR 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

.IR fildes

is associated with a pseudo-terminal, the START character need not be

transmitted.

.P

The default on the opening of a terminal file is that neither its input

nor its output are suspended.

.P

Attempts to use

\fItcflow\fR()

from a process which is a member of a background process group on a

.IR 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.

.SH "RETURN VALUE"

Upon successful completion, 0 shall be returned. Otherwise, \(mi1

shall be returned and

.IR errno

set to indicate the error.

.SH ERRORS

The

\fItcflow\fR()

function shall fail if:

.TP

.BR EBADF

The

.IR fildes

argument is not a valid file descriptor.

.TP

.BR EINVAL

The

.IR action

argument is not a supported value.

.TP

.BR EIO

The process group of the writing process is orphaned, the calling thread

is not blocking SIGTTOU, and the process is not ignoring SIGTTOU.

.TP

.BR ENOTTY

The file associated with

.IR fildes

is not a terminal.

.LP

.IR "The following sections are informative."

.SH EXAMPLES

None.

.SH "APPLICATION USAGE"

None.

.SH RATIONALE

None.

.SH "FUTURE DIRECTIONS"

None.

.SH "SEE ALSO"

.IR "\fItcsendbreak\fR\^(\|)"

.P

The Base Definitions volume of POSIX.1\(hy2008,

.IR "Chapter 11" ", " "General Terminal Interface",

.IR "\fB<termios.h>\fP"

.SH COPYRIGHT

Portions of this text are reprinted and reproduced in electronic form

from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology

-- Portable Operating System Interface (POSIX), The Open Group Base

Specifications Issue 7, Copyright (C) 2013 by the Institute of

Electrical and Electronics Engineers, Inc and The Open Group.

(This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) In the

event of any discrepancy between this version and the original IEEE and

The Open Group Standard, the original IEEE and The Open Group Standard

is the referee document. The original Standard can be obtained online at

http://www.unix.org/online.html .

Any typographical or formatting errors that appear

in this page are most likely

to have been introduced during the conversion of the source files to

man page format. To report such errors, see

https://www.kernel.org/doc/man-pages/reporting_bugs.html .