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. Since 7 bits are available to represent each character it is possible to represent a total of 128 different characters.
An table of the ASCII character set can be found in the file /usr/pub/ascii on every UNIX system.