Problem

1. How do you

(i) print every line of a file twice,

(ii) insert a blank line after each line that is read?

2. How will you replace - with _ and vice versa, assuming that the file doesn't contain any numerals?

3. What shortcut does sed offer to replace the string Linux with Red Hat Linux?

4. How do you add two spaces at the beginning of every line?

5. Invert the name of the individual in emp.lst so that the surname occurs first.