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

PROLOG

       This  manual page is part of the POSIX Programmer's Manual.  The Linux implementation of this interface may differ (consult the correspond-
       ing Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.

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 file associated with the fildes argument is not 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 POSIX.1-2008, <unistd.h>

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2013 Edition, Standard for Information Technol-
       ogy  --	Portable  Operating  System  Interface (POSIX), The Open Group Base Specifications Issue 7, Copyright (C) 2013 by the Institute of
       Electrical and Electronics Engineers, Inc and The Open Group.  (This is POSIX.1-2008 with the 2013 Technical Corrigendum 1 applied.) 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 Stan-
       dard is the referee document. The original Standard can be obtained online at http://www.unix.org/online.html .

       Any typographical or formatting errors that appear in this page are most likely to have been introduced during the conversion of the source
       files to man page format. To report such errors, see https://www.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE
/The Open Group						       2013								ISATTY(3P)