NAME

       isatty - test whether a file descriptor refers to a terminal

SYNOPSIS

       #include <unistd.h>

       int isatty(int fd);

DESCRIPTION

       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 │
       └───────────┴───────────────┴─────────┘

CONFORMING TO

       POSIX.1-2001, POSIX.1-2008, SVr4, 4.3BSD.

SEE ALSO

       fstat(2), ttyname(3)

COLOPHON

       This  page  is  part  of  release  5.10  of  the  Linux man-pages project.  A description of the project,
       information  about  reporting  bugs,  and  the  latest  version  of  this   page,   can   be   found   at
       https://www.kernel.org/doc/man-pages/.

Linux                                              2019-03-06                                          ISATTY(3)