ISATTY(P)                                                                               ISATTY(P)



NAME
       isatty - test for a terminal device

SYNOPSIS
       #include <unistd.h>

       int isatty(int fildes);


DESCRIPTION
       The  isatty()  function  shall test whether fildes, an open file descriptor, is associated
       with a terminal device.

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

ERRORS
       The isatty() function may fail if:

       EBADF  The fildes argument is not a valid open file descriptor.

       ENOTTY The fildes argument is not associated with a terminal.


       The following sections are informative.

EXAMPLES
       None.

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

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       The Base Definitions volume of IEEE Std 1003.1-2001, <unistd.h>

COPYRIGHT
       Portions  of  this  text  are  reprinted  and  reproduced in electronic form from IEEE Std
       1003.1, 2003 Edition, Standard for Information Technology  --  Portable  Operating  System
       Interface  (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 by
       the Institute of Electrical and Electronics Engineers, Inc and  The  Open  Group.  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 orig-
       inal Standard can be obtained online at http://www.opengroup.org/unix/online.html .



POSIX                                          2003                                     ISATTY(P)