add_to_fstab

/dev/sda1     /     ext3     relatime,errors=remount-ro   0    1

current_in_fstab

ubuntu@ubuntu:~$ cat /etc/fstab
unionfs / unionfs rw 0 0
tmpfs /tmp tmpfs nosuid,nodev 0 0
/dev/sda5 swap swap defaults 0 0

new_fstab_before_reboot

ubuntu@ubuntu:~$ cat /etc/fstab
unionfs / unionfs rw 0 0
tmpfs /tmp tmpfs nosuid,nodev 0 0
/dev/sda1     /     ext3     relatime,errors=remount-ro   0    1
/dev/sda5 swap swap defaults 0 0

sudo fdisk -l

ubuntu@ubuntu:~$ sudo fdisk -l

Disk /dev/sda: 100.0 GB, 100030242816 bytes
255 heads, 63 sectors/track, 12161 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1       11661    93666951   83  Linux
/dev/sda2           11662       12161     4016250    5  Extended
/dev/sda5           11662       12161     4016218+  82  Linux swap / Solaris

Disk /dev/sdb: 4022 MB, 4022337536 bytes
12 heads, 4 sectors/track, 163669 cylinders
Units = cylinders of 48 * 512 = 24576 bytes

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1              23      163670     3927516    b  W95 FAT32