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 original Standard can be obtained online
at http://www.opengroup.org/unix/online.html .