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isatty 3C "24 Jul 2002" "SunOS 5.11" "Standard C Library Functions"
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(5) for descriptions of the following attributes:

ATTRIBUTE TYPEATTRIBUTE VALUE
Interface StabilityStandard
MT-LevelMT-Safe
SEE ALSO

ttyname(3C), attributes(5), standards(5)