Problem
1. Two lists, foo1 and foo2, contain names of users. How do you create a third list of users who are present in foo2 but absent in foo1? When will the command sequence not work properly?
2. How do you compare the contents of the file foo with the output of a program named a.out without saving the output to disk?
3. How do you select from a file
(i) lines 5 to 10,
(ii) second-to-last line?