TL;DR

Before disposing of a storage device, you must securely wipe all of its data. If only the command line interface is available on Linux, the process involves overwriting the device with junk or binary data, making it significantly harder to recover the original files. Unlike a standard delete operation, which merely removes file pointers, this method overwrites the actual data.

The steps include locating the device, unmounting it if necessary, wiping it, creating a new partition and partition table, and finally formatting the partition with a file system.

Securely Wipe a Storage Device Using Only the Linux Terminal

Step 1: Locate the Storage Device

Before formatting, determine the device name using:

lsblk

For a more detailed output, use:

sudo fdisk -l

Look for your storage device (e.g., /dev/sdX, where X is the device letter). M.2 devices are commonly named /dev/nvmeXnY.

lsblk commandStandard output when using lsblk command

Step 2: Unmount the Device

If the device is mounted, unmount it first:

sudo umount /dev/sdX

If it has multiple partitions, unmount all of them (e.g., /dev/sdX1, /dev/sdX2, etc.):

sudo umount /dev/sdX1
sudo umount /dev/sdX2

umount commandStandard output and error messages when a device is mounted or not

Step 3: Wipe the Storage Device

To completely erase the device, use one of the following methods:

Option 1: Overwrite with Zeroes (Slow but Secure)

sudo dd if=/dev/zero of=/dev/sdX bs=1M status=progress

This command performs the following operations:

  • if=/dev/zero → Reads from /dev/zero (a stream of zeroes).
  • of=/dev/sdX → Writes to the specified device.
  • bs=1M → Sets block size to 1MB for faster writing.
  • status=progress → Displays progress updates.

dd commandStatus progress of the dd command

DISCLAIMER: This process may take several hours. The actual duration depends on the storage device and system performance.

Option 2: Use shred for Multiple Overwrites (More Secure)

sudo shred -v -n 4 -z -u /dev/sdX
  • -v → Verbose mode (shows progress).
  • -n 4 → Overwrites the device 4 times (default is 3).
  • -z (optional) → Overwrites with zeroes after shredding.
  • -u (optional) → Removes files when done.

shred end processFinal shred output

DISCLAIMER: This process may take several hours. The actual duration depends on the storage device and system performance.

Once done, list the block devices again. Storage devices should be listed without any partitions. If partitions are still visible, reboot the system.

wiped storage devicesWiped storage devices sdd and sdc

Step 4: Create a New Partition Table

To create a new partition table (GPT or MBR), note that the Master Boot Record (MBR) is the traditional choice but has limitations. Many server administrators prefer the GUID Partition Table (GPT) because it supports more partitions, which is crucial for high-capacity storage devices.

For GPT (Recommended for modern systems):

sudo parted /dev/sdX mklabel gpt

For MBR (For older systems):

sudo parted /dev/sdX mklabel msdos

Step 5: Create a New Partition

Using fdisk:

sudo fdisk /dev/sdX

Inside fdisk:

  1. Press n (to create a new partition).
  2. Choose a partition number (default: 1).
  3. Select the starting and ending sectors (default values are usually fine).
  4. Press w to write the changes.

fdisk partitionPartitioning a device using fdisk

Alternatively, using parted:

sudo parted -a optimal /dev/sdX mkpart primary ext4 0% 100%

Replace ext4 with another filesystem type if needed.

parted deviceA: Initial state. B: After partitioning.

Step 6: Format the Partition with a Filesystem

Once the partition is created (e.g., /dev/sdX1), format it with the desired filesystem:

  • EXT4 (Common for Linux): 
    sudo mkfs.ext4 /dev/sdX1
  • NTFS (For Windows compatibility): 
    sudo mkfs.ntfs /dev/sdX1
  • FAT32 (Cross-platform compatibility, max file size: 4GB): 
    sudo mkfs.vfat -F32 /dev/sdX1
  • exFAT (For large files, cross-platform support): 
    sudo mkfs.exfat /dev/sdX1
  • XFS (High performance for large files): 
    sudo mkfs.xfs /dev/sdX1

make filesystemFormatting a partition with NTFS.

Step 7: Mount the New Partition

Finally, mount the device and verify that it is working.

Create a mount point and mount the partition:

sudo mkdir -p /mnt/mydisk
sudo mount /dev/sdX1 /mnt/mydisk

Verify the mount status with:

df -h