Quick Answer
The answer is blkid /dev/sdb1. This command is the most direct and reliable method to display a filesystem's UUID because it queries the kernel’s device mapper and reads the filesystem superblock to extract block device attributes like the universally unique identifier and filesystem type. On the Linux Foundation Certified System Administrator LFCS exam, this tests your ability to identify and manage storage devices using low-level utilities, often appearing in scenarios where you must verify disk identifiers before mounting or configuring fstab. A common trap is confusing blkid with lsblk -f, which also shows UUIDs but formats output differently; blkid is preferred for scripting and precise device queries. Remember the mnemonic “Block ID” for blkid—it’s the go-to tool for UUIDs, not just listing block devices.
This LFCS practice question tests your understanding of storage management. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
Which command can be used to display the UUID of a filesystem on /dev/sdb1?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "which command"
Why it matters: Tests specific CLI syntax. Recall the exact command and its required context — near-synonyms and partial matches are common distractors.
blkid /dev/sdb1
blkid displays UUID and filesystem type.
tune2fs -l /dev/sdb1
Why wrong: tune2fs works only on ext filesystems and requires root.
df -h /dev/sdb1
Why wrong: df shows disk usage, not UUID.
lsblk /dev/sdb1
Why wrong: lsblk shows block device info but not UUID by default.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
blkid /dev/sdb1
The blkid command is specifically designed to locate and print block device attributes, including the UUID and filesystem type. When run against a device like /dev/sdb1, it queries the kernel's device mapper and reads the filesystem superblock to extract the universally unique identifier (UUID). This is the most direct and reliable method for displaying a filesystem's UUID.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
blkid /dev/sdb1
Why this is correct
blkid displays UUID and filesystem type.
Clue confirmation
The clue word "which command" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
tune2fs -l /dev/sdb1
Why it's wrong here
tune2fs works only on ext filesystems and requires root.
df -h /dev/sdb1
Why it's wrong here
df shows disk usage, not UUID.
lsblk /dev/sdb1
Why it's wrong here
lsblk shows block device info but not UUID by default.
Common exam traps
The trap here is that candidates often assume tune2fs -l is the universal UUID display tool, but it only works on ext2/3/4 filesystems, whereas blkid works across all Linux filesystem types and is the standard command for this task.
Trap categories for this question
Command / output trap
df shows disk usage, not UUID.
Detailed technical explanation
The UUID is a 128-bit value stored in the filesystem superblock (e.g., at offset 0x468 for ext4) and is used by the kernel to uniquely identify filesystems, especially in /etc/fstab for persistent mounting. The blkid command reads this from the /sys/block hierarchy and the libblkid library, which caches results in /run/blkid/blkid.tab for performance. In real-world scenarios, using UUIDs prevents boot failures when disk device names change (e.g., /dev/sda becoming /dev/sdb after adding a new disk).
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A practitioner preparing for the LFCS exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
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FAQ
Storage Management — This question tests Storage Management — Read the scenario before looking for a memorised answer..
The correct answer is: blkid /dev/sdb1 — The blkid command is specifically designed to locate and print block device attributes, including the UUID and filesystem type. When run against a device like /dev/sdb1, it queries the kernel's device mapper and reads the filesystem superblock to extract the universally unique identifier (UUID). This is the most direct and reliable method for displaying a filesystem's UUID.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Yes — watch for: "which command". Tests specific CLI syntax. Recall the exact command and its required context — near-synonyms and partial matches are common distractors.
Read the scenario before looking for a memorised answer.
About these practice questions
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Last reviewed: Jun 11, 2026
This LFCS practice question is part of Courseiva's free Linux Foundation certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the LFCS exam.
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