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 VALUE

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.

 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.

 FUTURE DIRECTIONS

None.

 SEE ALSO

<unistd.h>.

DERIVATION

Derived from Issue 1 of the SVID.