wipefs

Display signatures for specified device

$ sudo wipefs [/dev/sdX]

$ sudo wipefs [[-a|--all]] [/dev/sdX]

$ sudo wipefs [[-a|--all]] [/dev/sdX]*

$ sudo wipefs [[-a|--all]] [[-n|--no-act]] [/dev/sdX]

$ sudo wipefs [[-a|--all]] [[-f|--force]] [/dev/sdX]

wipefs [options] device

-a, --all
    Wipe all known signatures from the device.

-b, --backup
    Create a signature backup file (e.g., wipefs--.bak) before wiping. The backup contains the byte sequence that was overwritten.

-f, --force
    Force the wipe operation, even if the device is mounted or contains a partition table. Use with extreme caution as this can lead to data corruption.

-h, --help
    Display a help message and exit.

-i, --no-empty
    Don't exit with a non-zero status if no signatures are found for the specified offset or type.

-l, --list
    List all detected signatures from the specified device. This is a non-destructive operation.

-n, --no-action
    Perform a dry run. Show what would be done without actually writing any changes to the device. Highly recommended before destructive operations.

-O, --offset
    Specify the byte offset where the signature is located. This allows wiping only a specific signature at a precise location.

-q, --quiet
    Suppress output messages, only show errors.

-r, --raw
    Use raw output format for the --list option, useful for scripting.

-t, --type
    Limit the signature types to be scanned or wiped. Multiple types can be specified comma-separated (e.g., ext4,swap). Known types include filesystems (ext2, xfs, fat, ntfs), LVM, RAID, and partition tables (dos, gpt).

-V, --version
    Display version information and exit.

device
    The block device or partition (e.g., /dev/sda, /dev/sdb1) to operate on. This argument is required.

wipefs is a utility for erasing filesystem, RAID, or partition table signatures (often called 'magic strings') from a specified block device or partition.

It is commonly used to prepare a disk or partition for a new filesystem or partition table, especially when a device has previously been used and retains old metadata that might confuse other utilities like mkfs or fdisk.

The command can identify a wide range of signatures, including those for various filesystems (e.g., ext, xfs, fat, ntfs), swap areas, LVM, and RAID. It offers options to list existing signatures (-l) or perform a dry run (-n) before committing to a destructive operation, which is highly recommended. As wipefs directly modifies disk metadata, it requires root privileges and should be used with extreme caution to avoid irreversible data loss.

• Irreversible Data Loss: wipefs permanently removes data. Misuse or incorrect device specification can lead to irreparable data loss. Always double-check the target device.
• Root Privileges: This command requires superuser (root) privileges to operate on block devices.
• Mounted Devices: Wiping a device that is currently mounted, especially with the --force option, can severely corrupt the filesystem and lead to system instability. Always unmount filesystems before using wipefs on them.
• Partition Tables: Removing partition table signatures (e.g., dos for MBR, gpt) will make the entire disk unreadable until a new partition table is created, effectively erasing all partition information.

wipefs maintains an internal database of known filesystem, RAID, LVM, and partition table signatures (magic bytes). This allows it to accurately identify and target specific metadata for removal. The types recognized by wipefs can be listed using the --help output under the --type option section, which typically includes a wide array of common formats.

Before any destructive operation, it is highly recommended to use wipefs -l to list existing signatures and wipefs -a -n for a dry run. Always ensure you are operating on the correct device to prevent accidental data loss on critical disks.

wipefs is a component of the util-linux project, a venerable collection of essential system utilities for Linux. It emerged to provide a more specific, safer, and user-friendly alternative to generic tools like dd for removing filesystem or partition metadata. Its development has focused on accurate signature identification and offering protective features like dry-run and listing capabilities, making it a dedicated tool for disk metadata manipulation.

fdisk(8), parted(8), mkfs(8), lsblk(8), dd(1), mkswap(8)