isatty

Tests whether the specified file descriptor refers to a terminal device.

Library:LibC

Classification:POSIX

Service:File and Directory I/O

Syntax

  #include <unistd.h> 
   
  int isatty (
     int   fildes);

Returns

1 if the device is a character device
0 if the device is not a character device and sets errno to one of the following values.

Decimal	Constant	Description
4	EBADF	The fildes parameter isn't a valid file descriptor.
75	ENOTTY	The fildes parameter doesn't refer to a terminal device.

The isatty function tests if the opened file or device referenced by the file descriptor is a character device (namely, the console).