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(5) for descriptions of the following attributes:


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

SEE ALSO


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


July 24, 2002 ISATTY(3C)