findfs

Search block devices by filesystem label

$ findfs LABEL=[label]

$ findfs UUID=[uuid]

$ findfs PARTLABEL=[partition_label]

$ findfs PARTUUID=[partition_uuid]

findfs [fs-options] LABEL=label | UUID=uuid

LABEL=label
    Search for filesystem by human-readable label name

UUID=uuid
    Search for filesystem by unique identifier (e.g., 12345678-1234-1234-1234-123456789abc)

-t, --type FSTYPE
    Restrict search to filesystems of type (e.g., ext4, vfat)

-o, --output FORMAT
    Set output format (default: device; others: list, name, value, full)

--help
    Display usage information

--version
    Print version information

findfs is a utility from the util-linux package designed to locate the block device associated with a filesystem using its LABEL or UUID. It is invaluable in boot scripts, fstab configurations, and automation tasks where device names like /dev/sda1 may change due to hardware reconfiguration or kernel updates.

The command internally invokes blkid(8) to scan all available block devices, matching the specified label or UUID, and outputs the full device path of the first match. For instance, running findfs LABEL=root might return /dev/sda2 if that partition has the label "root".

Labels are human-readable strings set with tools like e2label or fatlabel, while UUIDs are unique 128-bit identifiers generated during formatting. Using them ensures stability over volatile device node names. findfs accepts fs-options from blkid, allowing refinements like filesystem type restrictions. It exits with 0 on success, 4 if no match, or other codes for errors.

This tool promotes portable scripting, especially in environments with dynamic storage like LVM or RAID.

Returns only the first matching device; scanning can be slow on systems with many block devices. Requires root for some blkid features. No match exits with code 4.

findfs LABEL=boot
Outputs: /dev/sda1 (if matching label)

findfs UUID=12345678-1234-1234-1234-123456789abc -t ext4
Outputs device with matching UUID and ext4 type

ROOTDEV=$(findfs LABEL=root)
Mounts via variable in scripts

Introduced in util-linux 2.14 (2008) as a convenience wrapper for blkid label/UUID searches, evolving with blkid enhancements in later releases like 2.23+ for better performance.

blkid(8), lsblk(8), tune2fs(8), e2label(8)