1TCFLOW(3P)                 POSIX Programmer's Manual                TCFLOW(3P)
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PROLOG

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

12       tcflow - suspend or restart the transmission or reception of data
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SYNOPSIS

15       #include <termios.h>
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17       int tcflow(int fildes, int action);
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DESCRIPTION

21       The tcflow() function shall suspend or restart transmission  or  recep‐
22       tion  of  data  on  the  object referred to by fildes, depending on the
23       value of action. The fildes argument is an open file descriptor associ‐
24       ated with a terminal.
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26        * If action is TCOOFF, output shall be suspended.
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28        * If action is TCOON, suspended output shall be restarted.
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30        * If  action  is  TCIOFF,  the system shall transmit a STOP character,
31          which is intended to cause the terminal device to stop  transmitting
32          data to the system.
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34        * If  action  is  TCION,  the system shall transmit a START character,
35          which is intended to cause the terminal device to start transmitting
36          data to the system.
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38       The default on the opening of a terminal file is that neither its input
39       nor its output are suspended.
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41       Attempts to use tcflow() from a process which is a member  of  a  back‐
42       ground process group on a fildes associated with its controlling termi‐
43       nal, shall cause the process group to be sent a SIGTTOU signal. If  the
44       calling  process  is  blocking or ignoring SIGTTOU signals, the process
45       shall be allowed to perform the operation, and no signal is sent.
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RETURN VALUE

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

52       The tcflow() function shall fail if:
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54       EBADF  The fildes argument is not a valid file descriptor.
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56       EINVAL The action argument is not a supported value.
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58       ENOTTY The file associated with fildes is not a terminal.
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61       The tcflow() function may fail if:
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63       EIO    The  process  group  of the writing process is orphaned, and the
64              writing process is not ignoring or blocking SIGTTOU.
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67       The following sections are informative.
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EXAMPLES

70       None.
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APPLICATION USAGE

73       None.
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RATIONALE

76       None.
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FUTURE DIRECTIONS

79       None.
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SEE ALSO

82       tcsendbreak(), the Base  Definitions  volume  of  IEEE Std 1003.1-2001,
83       Chapter 11, General Terminal Interface, <termios.h>, <unistd.h>
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86       Portions  of  this text are reprinted and reproduced in electronic form
87       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
88       --  Portable  Operating  System  Interface (POSIX), The Open Group Base
89       Specifications Issue 6, Copyright (C) 2001-2003  by  the  Institute  of
90       Electrical  and  Electronics  Engineers, Inc and The Open Group. In the
91       event of any discrepancy between this version and the original IEEE and
92       The  Open Group Standard, the original IEEE and The Open Group Standard
93       is the referee document. The original Standard can be  obtained  online
94       at http://www.opengroup.org/unix/online.html .
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98IEEE/The Open Group                  2003                           TCFLOW(3P)
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