isatty - test whether a file descriptor refers to a terminal
#include <unistd.h>
int isatty(int fd);
The
isatty() function tests whether
fd is an open file descriptor
referring to a terminal.
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.
- 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).
For an explanation of the terms used in this section, see
attributes(7).
| Interface |
Attribute |
Value |
| isatty () |
Thread safety |
MT-Safe |
POSIX.1-2001, POSIX.1-2008, SVr4, 4.3BSD.
fstat(2),
ttyname(3)