ISATTY(3C) Standard C Library Functions ISATTY(3C)

NAME

isatty - test for a terminal device

SYNOPSIS

#include <unistd.h>

int isatty(int fildes);

DESCRIPTION

The isatty() function tests whether fildes, an open file descriptor, is
associated with a terminal device.

RETURN VALUES

The isatty() function returns 1 if fildes is associated with a terminal;
otherwise it returns 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.

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.

ATTRIBUTES

See attributes(7) for descriptions of the following attributes:


+--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+-----------------+
|Interface Stability | Standard |
+--------------------+-----------------+
|MT-Level | MT-Safe |
+--------------------+-----------------+

SEE ALSO

ttyname(3C), attributes(7), standards(7)


July 24, 2002 ISATTY(3C)