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

6       isatty - test for a terminal device
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SYNOPSIS

9       #include <unistd.h>
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11       int isatty(int fildes);
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DESCRIPTION

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

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

24       The isatty() function may fail if:
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26       EBADF  The fildes argument is not a valid open file descriptor.
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28       ENOTTY The fildes argument is not associated with a terminal.
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31       The following sections are informative.
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EXAMPLES

34       None.
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APPLICATION USAGE

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

42       None.
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FUTURE DIRECTIONS

45       None.
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SEE ALSO

48       The Base Definitions volume of IEEE Std 1003.1-2001, <unistd.h>
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51       Portions of this text are reprinted and reproduced in  electronic  form
52       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
53       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
54       Specifications  Issue  6,  Copyright  (C) 2001-2003 by the Institute of
55       Electrical and Electronics Engineers, Inc and The Open  Group.  In  the
56       event of any discrepancy between this version and the original IEEE and
57       The Open Group Standard, the original IEEE and The Open Group  Standard
58       is  the  referee document. The original Standard can be obtained online
59       at http://www.opengroup.org/unix/online.html .
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63IEEE/The Open Group                  2003                            ISATTY(P)
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