Mode update opens the file for writing, positioning the file-pointer at the beginning of the file without truncating the file. Stream is either a variable, in which case it is bound to an integer identifying the stream, or an atom, in which case this atom will be the stream identifier. Using type binary the bytes will be read or written without any translation. Note there is no difference between the two on Unix systems. Gives the stream a name.
Repetitive reading keeps yielding the same result.
With action reset , Prolog will examine the file again and return more data if the file has grown. The option reposition is not supported in SWI-Prolog. All streams connected to a file may be repositioned. Open a stream that produces no output. All counting functions are enabled on such a stream.