Name

isatty - check if a file descriptor is a TTY

Synopsis

#include <unistd.h>

int isatty(int fd);

Description

Checks if the device inside a given file descriptor is a TTY device.

Return value

If fd refers to a TTY device, returns 1. Otherwise, returns 0 and errno is set to describe the error.

Errors

• EBADF: fd is not an open file descriptor.
• ENOTTY: fd refers to something that's not a TTY device.
• EINVAL: fd refers to something that supports ioctl(), but is still not a TTY device.