... a set of permissions associated with every file and directory that determine who can read it, write to it, or execute it. Only the owner of the file (or the super-user) can change these permissions. a mathematical term that refers to a number, character or word which changes the action of the command it is applied to. a standard code used for representing information on computer systems and networks. It uses the printing and non-printing characters that can be generated by the keyboard. ...