1ISATTY(3P)                 POSIX Programmer's Manual                ISATTY(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

13       isatty — test for a terminal device
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SYNOPSIS

16       #include <unistd.h>
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18       int isatty(int fildes);
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DESCRIPTION

21       The isatty() function shall test whether fildes, an open file  descrip‐
22       tor, is associated with a terminal device.
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RETURN VALUE

25       The  isatty()  function  shall  return 1 if fildes is associated with a
26       terminal; otherwise, it shall return 0 and may set  errno  to  indicate
27       the error.
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ERRORS

30       The isatty() function may fail if:
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32       EBADF  The fildes argument is not a valid open file descriptor.
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34       ENOTTY The file associated with the fildes argument is not a terminal.
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36       The following sections are informative.
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EXAMPLES

39       None.
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APPLICATION USAGE

42       The  isatty() function does not necessarily indicate that a human being
43       is available for interaction via fildes.  It  is  quite  possible  that
44       non-terminal devices are connected to the communications line.
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RATIONALE

47       None.
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FUTURE DIRECTIONS

50       None.
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SEE ALSO

53       The Base Definitions volume of POSIX.1‐2008, <unistd.h>
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56       Portions  of  this text are reprinted and reproduced in electronic form
57       from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
58       --  Portable  Operating  System  Interface (POSIX), The Open Group Base
59       Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
60       cal  and  Electronics  Engineers,  Inc  and  The  Open Group.  (This is
61       POSIX.1-2008 with the 2013 Technical Corrigendum  1  applied.)  In  the
62       event of any discrepancy between this version and the original IEEE and
63       The Open Group Standard, the original IEEE and The Open Group  Standard
64       is  the  referee document. The original Standard can be obtained online
65       at http://www.unix.org/online.html .
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67       Any typographical or formatting errors that appear  in  this  page  are
68       most likely to have been introduced during the conversion of the source
69       files to man page format. To report such errors,  see  https://www.ker‐
70       nel.org/doc/man-pages/reporting_bugs.html .
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74IEEE/The Open Group                  2013                           ISATTY(3P)
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