centos man page for isatty

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 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(3P)