How to Set a Custom Bash Shell Prompt String (PS0/PS1/PS2/PS3/PS4) in Linux
Bourne Shell Prompt CIS 218. BASH Prompt Prompt is controlled via a special shell variable PS1, PS2, PS3 and PS4. If set, the value is executed as a command. - ppt download
How far the PlayStation has come ( PS1,PS2, PS3, PS4) - YouTube