user@debian:~$ sudo fdisk -l
Ignoring extra extended partition 3

Disk /dev/sda: 20.0 GB, 20000000000 bytes
255 heads, 63 sectors/track, 2431 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xa834a834

This doesn't look like a partition table
Probably you selected the wrong device.

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1               1         408     3277228+   7  HPFS/NTFS
/dev/sda2             409        2434    16273814+   5  Extended
/dev/sda3   ?           1           1           0   85  Linux extended
Partition 3 does not end on cylinder boundary.
/dev/sda5             409        2343    15542856   83  Linux
/dev/sda6            2344        2434      730926   82  Linux swap / Solaris

Partition table entries are not in disk order

Disk /dev/sdb: 2002 MB, 2002747392 bytes
32 heads, 63 sectors/track, 1940 cylinders
Units = cylinders of 2016 * 512 = 1032192 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x0ee9779f

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1   *           1        1940     1955488+   b  W95 FAT32