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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.

       EINVAL fd refers  to  a  file  other  than  a  terminal.   POSIX.1-2001
              specifies the error ENOTTY for this case.

CONFORMING TO

       SVr4, 4.3BSD, POSIX.1-2001.

SEE ALSO

       fstat(2), ttyname(3)

COLOPHON

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       description of the project, and information about reporting  bugs,  can
       be found at http://www.kernel.org/doc/man-pages/.