man pages section 3: Basic Library Functions

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Updated: July 2014
 
 

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
Committed
MT-Level
MT-Safe
Standard

See Also

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