isatty(3C)

NAME

     isatty - test for a terminal device

SYNOPSIS

     #include <unistd.h>

     int isatty(int fildes);

DESCRIPTION

     The isatty() function tests whether  fildes,  an  open  file
     descriptor, is associated with a terminal device.

RETURN VALUES

     The isatty() function returns 1 if fildes is associated with
     a  terminal;  otherwise  it  returns  0 and may set errno to
     indicate the error.

ERRORS

     The isatty() function may fail if:

     EBADF The fildes argument is not a valid open file  descrip-
           tor.

     ENOTTY
           The fildes argument is not associated with a terminal.

USAGE

     The isatty() function does not necessarily indicate  that  a
     human  being  is available for interaction via fildes. It is
     quite possible that non-terminal devices  are  connected  to
     the communications line.

ATTRIBUTES

     See attributes(5) for descriptions of the  following  attri-
     butes:

     ____________________________________________________________
    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    |_____________________________|_____________________________|
    | MT-Level                    | MT-Safe                     |
    |_____________________________|_____________________________|

SEE ALSO

     ttyname(3C), attributes(5)