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.1‐2008, <unistd.h>

COPYRIGHT¶

Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology -- 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 Standard 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 .