Quick Answer
The answer is `blkid /dev/sda1` and `lsblk -o UUID /dev/sda1`. Both commands work by directly reading the filesystem superblock or the libblkid cache to retrieve the universally unique identifier assigned to the block device during formatting, bypassing any reliance on the `/etc/fstab` file or mount points. On the Red Hat Certified System Administrator EX200 exam, this tests your ability to identify block devices without mounting them, a common task when troubleshooting boot issues or configuring persistent storage. A frequent trap is confusing `lsblk -f` (which shows filesystem type and label) with the UUID-specific filter; the `-o UUID` option isolates only the UUID column, while `blkid` outputs the UUID alongside other attributes. Remember the mnemonic: “Blkid is quick, lsblk with -o is picky” — blkid gives you the UUID directly, while lsblk needs the `-o UUID` flag to filter for it.
This EX200 practice question tests your understanding of create and configure file systems. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. 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 TWO commands can be used to check the UUID of a filesystem on /dev/sda1?
e2label /dev/sda1
Why wrong: Shows label, not UUID.
findmnt /dev/sda1
Why wrong: Shows mount options.
lsblk -o UUID /dev/sda1
Displays UUID.
blkid /dev/sda1
Displays UUID.
file -s /dev/sda1
Why wrong: Shows filesystem type.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
lsblk -o UUID /dev/sda1
The `blkid` command directly queries the UUID of a block device from the libblkid cache or by reading the filesystem superblock, and `lsblk -o UUID` filters the lsblk output to show only the UUID column for the specified device. Both commands reliably retrieve the UUID of /dev/sda1.
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.
e2label /dev/sda1
Why it's wrong here
Shows label, not UUID.
findmnt /dev/sda1
Why it's wrong here
Shows mount options.
lsblk -o UUID /dev/sda1
Why this is correct
Displays UUID.
Related concept
Read the scenario before looking for a memorised answer.
blkid /dev/sda1
Why this is correct
Displays UUID.
Related concept
Read the scenario before looking for a memorised answer.
file -s /dev/sda1
Why it's wrong here
Shows filesystem type.
Common exam traps
The trap here is that candidates confuse `e2label` (which only handles labels) with UUID retrieval, or assume `findmnt` shows UUIDs by default when it actually requires explicit column selection.
Trap categories for this question
Command / output trap
Shows label, not UUID.
Detailed technical explanation
The UUID is stored in the filesystem superblock at a fixed offset (e.g., offset 0x468 for ext4). `blkid` reads this superblock directly or uses a cached udev database, while `lsblk` queries the sysfs filesystem under /sys/block for the device's UUID attribute. In scripting, `blkid -s UUID -o value /dev/sda1` is often used to extract just the UUID string.
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 EX200 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.
Create and configure file systems — study guide chapter
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FAQ
Create and configure file systems — This question tests Create and configure file systems — Read the scenario before looking for a memorised answer..
The correct answer is: lsblk -o UUID /dev/sda1 — The `blkid` command directly queries the UUID of a block device from the libblkid cache or by reading the filesystem superblock, and `lsblk -o UUID` filters the lsblk output to show only the UUID column for the specified device. Both commands reliably retrieve the UUID of /dev/sda1.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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Last reviewed: Jun 11, 2026
This EX200 practice question is part of Courseiva's free Red Hat 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 EX200 exam.
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