(a) (3 marks) What is difference between a job and a process in a Unix system? (b) (3 marks) What is difference between background and foreground processses? (c) (5 marks) Write an egrep command that prints all lines from the standard input which contain a substring of four letters that appear three times (with no overlaps). For example, the line: Consider this line, and the word side one sideline should be printed because it contains substring side three times. (d) (3 marks) How can we change the prompt string in the bash shell? (e) (3 marks) What is the purpose of the chsh command?