(PHP 4, PHP 5, PHP 7)
posix_isatty — Determine if a file descriptor is an interactive terminal
    Determines if the file descriptor fd refers to a valid
    terminal type device.
  
fdThe file descriptor, which is expected to be either a file resource or an integer. An integer will be assumed to be a file descriptor that can be passed directly to the underlying system call.
In almost all cases, you will want to provide a file resource.
   Returns TRUE if fd is an open descriptor connected
   to a terminal and FALSE otherwise.