Book A command is a request to perform an operation or run a program. You use commands to tell the AIX Operating System what task you want it to perform. Some commands can be entered simply by typing one word. It is also possible to combine commands so that the output from one command becomes the input for another command. This is known as pipelining.
Flags further define the actions of commands.
A flag is a modifier used with the command name on the command line, usually preceded by a dash. Commands can also be grouped together and stored in a file. These are known as shell procedures or shell scripts. Instead of executing the commands individually, you execute the file that contains the commands. Also identifies graphical objects such as buttons, labels, and icons that the user selects.