Close close a file close int pn os9 I$CLOSE Close takes a path number, "pn", as returned from system calls "open()", "creat()", or "dup()", and closes the associated file. Termination of a task always closes all open files automatically, but it is necessary to close files where multiple files are opened by the task, and it is desired to re-use path numbers to avoid going over the system or process path number limit. creat(), open(), dup()