isatty

       #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 ter-
       minal; otherwise 0 is returned, and errno is set to indicate the error.

ERRORS
       EBADF  fd is not a valid file descriptor.

       EINVAL fd  refers  to  a file other than a terminal.  POSIX.1 specifies
              the error ENOTTY for this case.

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 4.04 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
       http://www.kernel.org/doc/man-pages/.

Linux                             2015-08-08                         ISATTY(3)
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