ISATTY
Section: POSIX Programmer's Manual (3P)
Updated: 2017
Page Index
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
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.1-2017,
<unistd.h>
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1-2017, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 7, 2018 Edition,
Copyright (C) 2018 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 .
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 .