LPIC-1 Devices, Filesystems and FHS Practice Question
An administrator runs `fsck /dev/sdb1` on an ext4 filesystem that is currently mounted. What is the likely outcome?
⚠ Common exam trap
It's easy for candidates to assume fsck can safely perform a read-only check on a mounted filesystem, but the LPIC-1 exam tests the specific rule that fsck refuses to run on any mounted filesystem (except with special options like -f for root in single-user mode) to prevent data corruption.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
It will refuse and exit with a warning
Running fsck on a mounted ext4 filesystem is unsafe because the kernel may have cached metadata that differs from the on-disk state, leading to false corruption detection or actual data loss. The fsck tool detects the mounted state via /proc/mounts or the kernel's internal mount table and refuses to run, printing a warning and exiting with a non-zero exit code (typically 8). This is a deliberate safety mechanism to prevent filesystem corruption.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
It will succeed and repair any errors
Why it's wrong here
It will not proceed at all due to mounted state.
- ✗
It will automatically remount the filesystem read-only and check
Why it's wrong here
fsck does not automatically remount; it expects the admin to unmount first.
- ✓
It will refuse and exit with a warning
Why this is correct
fsck detects the filesystem is mounted and aborts to prevent damage.
- ✗
It will safely perform a read-only check
Why it's wrong here
Despite being read-only, fsck on a mounted filesystem can still cause inconsistency; it still refuses.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This LPIC-1 practice question is part of Courseiva's free LPI 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 LPIC-1 exam.