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I am selling my old laptop and I do not want my data to be recoverable with recovery tools.

I found this post How to wipe a hard disk completely so that no data recovery tools can retrieve anything? explaining that the shred command can do that.

I am just wondering on what partitions and in which order should I use this.

Here is the output of fdisk -l:

fdisk -l
Disk /dev/mmcblk0: 29.1 GiB, 31272730624 bytes, 61079552 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: someidentifier

Device           Start      End  Sectors  Size Type
/dev/mmcblk0p1    2048  1050623  1048576  512M EFI System
/dev/mmcblk0p2 1050624  2050047   999424  488M Linux filesystem
/dev/mmcblk0p3 2050048 61077503 59027456 28.2G Linux filesystem




Disk /dev/mmcblk0boot1: 4 MiB, 4194304 bytes, 8192 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/mmcblk0boot0: 4 MiB, 4194304 bytes, 8192 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/mapper/mmcblk0p3_crypt: 28.1 GiB, 30219960320 bytes, 59023360 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/mapper/ubuntu--vg-root: 26.2 GiB, 28143779840 bytes, 54968320 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes


Disk /dev/mapper/ubuntu--vg-swap_1: 1.9 GiB, 2051014656 bytes, 4005888 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes

Thank you

Andrea Lazzarotto
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Karim Mtl
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1 Answers1

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You are taking the wrong approach. If you want to clean up your data from the disk, shred the whole disk, not individual partitions.

The slack space could contain sensitive data, moreover its way easier to do it this way than remembering to shred all the partitions.

Also remember to do it from a live USB and ensure no other drives are connected so that you do not wipe them accidentally.

Andrea Lazzarotto
  • 8,164