1TCFLOW(P)                  POSIX Programmer's Manual                 TCFLOW(P)
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NAME

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

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

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

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

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

64       None.
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APPLICATION USAGE

67       None.
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RATIONALE

70       None.
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FUTURE DIRECTIONS

73       None.
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SEE ALSO

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