isatty3
Test whether a file descriptor refers to a terminal
Usage
#include <unistd.h>
int isatty(int fd);
Library
Standard C library (libc, -lc)
Overview
The isatty() function tests whether fd is an open file descriptor referring to a terminal.
Return value
isatty() returns 1 if fd is an open file descriptor referring to a terminal; otherwise 0 is returned, and errno is set to indicate the error.
Errors
- EBADF
-
fd is not a valid file descriptor.
- ENOTTY
-
fd refers to a file other than a terminal. On some older kernels, some types of files resulted in the error EINVAL in this case (which is a violation of POSIX, which specifies the error ENOTTY).
Attributes
For an explanation of the terms used in this section, see attributes(7).
| Interface | Attribute | Value |
| isatty() | Thread safety | MT-Safe |
Releases
19 releases since Debian 1.1 (Buzz); the text changed 14 times.