|| POSIX Programmer's Manual
PROLOG This manual page is part of the POSIX Programmer's Manual. The Linux implementation of this interface may differ (consult the corresponding Linux manual page for details of Linux behavior), or the interface may not be implemented on Linux.
NAME isatty - test for a terminal device
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.
() function may fail if:
fildes argument is not a valid open file descriptor.
fildes argument is not associated with a terminal.
The following sections are informative.
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.
FUTURE DIRECTIONS None.
SEE ALSO The Base Definitions volume of IEEE Std 1003.1-2001,
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 original Standard can be obtained online at http://www.opengroup.org/unix/online.html .