Problem
1. How do you locate all nonblank lines that don't begin with #, /*, or //?
2. Look up the format specifiers for the date command, and then frame a command sequence to list from emp.lst the names of the persons born today.
3. Devise a sequence to locate those users who have logged in yesterday or earlier but have not logged out, and mail the list to root. Users logged in more than once should feature only once in the list.