How to use the command 'wipefs' (with examples)

The wipefs command is a powerful utility used for managing filesystems by removing filesystem, RAID, or partition-table signatures from a specified device. It is especially useful in situations where one needs to repurpose a storage device or troubleshoot specific issues linked to filesystem signatures. wipefs allows users to take control over their storage setup by displaying pertinent information about current signatures and safely wiping them as needed, without affecting the actual data. It offers a range of options, from displaying present signatures to forcefully wiping them, ensuring flexibility and control.

Use case 1: Display signatures for specified device

Code:

sudo wipefs /dev/sdX

Motivation: One of the most important first steps when dealing with any drive is understanding its current status. Before making any changes, it’s crucial to see what signatures are present on a device to plan the next steps accordingly. Knowing existing signatures can help users decide whether a wipe is necessary or inform them about the current use of the drive, preventing accidental data loss.

Explanation:

• sudo: This command requires superuser privileges because it involves operations at the hardware level.
• wipefs: The base command to interact with filesystem signatures.
• /dev/sdX: This is the placeholder for the device target. Users must replace ‘sdX’ with the appropriate device identifier for their specific case.

Example Output:

offset               type
----------------------------------------------------------------
0x438                ext4   [filesystem]
0x1fe                dos    [partition table]

Use case 2: Wipe all available signature types for a specific device with no recursion into partitions

Code:

sudo wipefs --all /dev/sdX

Motivation: When preparing a device for a clean installation or when eliminating any remnants from previous usage, it’s essential to remove all types of signatures. However, the user might want to keep partition structures intact, focusing only on the specified device. This capability is helpful for users wanting to clean a drive without delving into the partitions.

Explanation:

• sudo: Ensures the command is run with elevated permissions necessary for disk operations.
• wipefs: The command to manipulate filesystem markers.
• --all: Tells wipefs to wipe all detected signatures on the specified device.
• /dev/sdX: Again, replace this with the actual device identifier.

Example Output:

/dev/sdX: 8 bytes were erased at offset 0x438 (ext4)
/dev/sdX: 2 bytes were erased at offset 0x1fe (dos)

Use case 3: Wipe all available signature types for the device and partitions using a glob pattern

Code:

sudo wipefs --all /dev/sdX*

Motivation: In scenarios where users need to clean not only the main device but also all its associated partitions, using this command with a glob pattern is particularly efficient. It helps ensure a thorough cleanup across the entire device, including any subdivided portions (partitions), which is often required before reallocating hardware or deep formatting tasks.

Explanation:

• sudo: Provides the necessary permissions.
• wipefs: The main command for signature management.
• --all: Erases all types of signatures from the device and its partitions.
• /dev/sdX*: Utilizes a glob pattern to include all partitions associated with /dev/sdX.

Example Output:

/dev/sdX1: 8 bytes were erased at offset 0x438 (ext4)
/dev/sdX2: 8 bytes were erased at offset 0x438 (ext4)

Use case 4: Perform dry run

Code:

sudo wipefs --all --no-act /dev/sdX

Motivation: The option for a dry run is invaluable when users want to understand what changes wipefs would make without actually implementing them. This approach is particularly useful for cautious users or in a testing environment to verify the outcomes of operations before committing to them, ensuring no accidental erasure of needed data.

Explanation:

• sudo: Executes the command with the necessary privileges.
• wipefs: The command to manage filesystem signatures.
• --all: Indicates all signatures should be handled.
• --no-act: This argument ensures that no actual changes are made, only simulating the action.
• /dev/sdX: The target device to be examined.

Example Output:

DRY-RUN: /dev/sdX: 8 bytes would be erased at offset 0x438 (ext4)
DRY-RUN: /dev/sdX: 2 bytes would be erased at offset 0x1fe (dos)

Use case 5: Force wipe, even if the filesystem is mounted

Code:

sudo wipefs --all --force /dev/sdX

Motivation: Sometimes, signs remain persistent or devices are in use, making standard operations ineffective. The force option allows users to override such concerns, forcibly wiping signatures even when the filesystem is mounted. This is crucial for situations where persistent or problematic signatures need to be removed without unmounting resources.

Explanation:

• sudo: Ensures the command is executed with appropriate access rights.
• wipefs: The signature manipulation command.
• --all: Specifies all signatures should be considered.
• --force: Overrides normal safeguards against wiping mounted devices.
• /dev/sdX: The target device which may be actively used.

Example Output:

/dev/sdX: 8 bytes were erased at offset 0x438 (ext4)

Conclusion:

The wipefs command is a versatile and crucial utility for those engaged in systems administration and maintenance tasks, particularly when dealing with drives and partitions. Its functionality allows for detailed assessment and deliberate management of filesystem signatures, providing flexibility for users seeking to tailor their approach based on specific scenarios. Whether displayed, selectively erased, or forcefully wiped, these processes ensure that managing storage devices is both efficient and reliable.