How to Use the 'blkid' Command (with Examples)

The blkid command is a utility in Unix-like operating systems used for listing and identifying block devices. Each block device, such as hard drives or USB drives, can contain multiple partitions, and blkid provides details about these partitions, including their Universally Unique Identifier (UUID). The UUID is a critical piece of information that helps differentiate between partitions, especially when managing filesystem mounts across different systems and sessions. This tool is essential for system administrators and users who need to manage storage devices efficiently.

Use Case 1: List All Partitions

Code:

sudo blkid

Motivation:

In a complex computing environment, you may have multiple storage devices connected at any given time. Each device can have various partitions, each potentially formatted with different filesystems. Understanding what devices and partitions are available, along with their UUIDs and filesystem types, is crucial for configuring access, managing backups, or simply verifying storage configurations. Running blkid provides a comprehensive overview of all recognized storage partitions, which can be particularly helpful after plugging in new hardware or diagnosing hardware changes in the current system setup.

Explanation:

• sudo: This command requires administrative privileges to access detailed information about block devices, as these operations can affect critical system components. Running blkid with sudo ensures that the command has the necessary permissions to view all devices, even those that are not accessible to standard users.

• blkid: This is the primary command to list block devices and their associated metadata. When used without additional options, blkid scans all block devices and provides essential information including UUID, filesystem type (TYPE), and labels.

Example Output:

/dev/sda1: UUID="e7f5ca0b-7b4c-4c2b-a0e4-958e7526d530" TYPE="ext4" PARTUUID="000b634e-01"
/dev/sda2: UUID="8E7F-1D27" TYPE="vfat" PARTUUID="000b634e-02"
/dev/sdb1: UUID="73ef8196-da73-495f-85b9-62f824456abc" TYPE="xfs" PARTUUID="04d4440e-01"

In this example, the system lists devices /dev/sda1, /dev/sda2, and /dev/sdb1 with their respective UUIDs, types of filesystems, and partition UUIDs.

Use Case 2: List All Partitions in a Table, Including Current Mountpoints

Code:

sudo blkid -o list

Motivation:

For system administrators and users managing disk partitions, understanding how and where each partition is mounted in the filesystem hierarchy is vital. This is especially relevant for tasks like automating backups, configuring new systems, developing scripts for system management, or even for educational purposes. Displaying partitions in a tabular form, along with their mount points, provides a quick overview that helps in the efficient management and understanding of storage resources.

Explanation:

• sudo: As with the previous use case, administrative access is crucial to gather comprehensive device information across the system peripherals.

• blkid: The core command responsible for retrieving block device information.

• -o list: This option changes the output format to a list. Instead of providing information for each partition on separate lines, this option organizes it neatly into a table. The table structure is particularly useful for quickly discerning which partitions are mounted and where, thereby facilitating system organization and analysis.

Example Output:

device     fs_type  label    mount point    UUID
-------------------------------------------------------------------------------------
/dev/sda1  ext4     rootfs   /              e7f5ca0b-7b4c-4c2b-a0e4-958e7526d530
/dev/sda2  vfat     boot     /boot          8E7F-1D27
/dev/sdb1  xfs      backup   /mnt/backup    73ef8196-da73-495f-85b9-62f824456abc

Here, the output provides a tabular view where /dev/sda1 is mounted on the root directory with the filesystem type ext4, and so forth up to /dev/sdb1, which is mounted on /mnt/backup.

Conclusion

The blkid command is a versatile utility that offers valuable insights into the partition structure and configuration of block devices on a Unix-like operating system. Whether you’re managing a single desktop, setting up a server or teaching system management, understanding and efficiently using blkid can significantly enhance your ability to navigate and control storage devices. With options to display information in different formats, it facilitates quick decision-making processes necessary for system stability and configuration management.