Sed Command activity
1. Delete the blank character at the beginning of the line in the / etc/grub.conf file
2. Replace the number 5 in the line "id:3:initdefault:" in the / etc/inittab file
3. Delete the blank lines in the / etc/inittab file
4. Delete the initial # sign in the / etc/inittab file
5. Delete the # sign and the white space character at the beginning of a file, but it is required that the # sign be followed by a white space character.
6. Delete the white space character and # at the beginning of the line of class # followed by the blank character in a file
7. Take out the directory name of a file path
