ISATTY(P)						     POSIX Programmer's Manual							 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 Technol-
       ogy -- 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 original Standard can  be  obtained
       online at http://www.opengroup.org/unix/online.html .

IEEE
/The Open Group						       2003								 ISATTY(P)