LPIC-1 Devices, Filesystems and FHS Practice Question
Exhibit
$ mount tmpfs on /tmp type tmpfs (rw,nosuid,nodev,noexec,relatime)
Refer to the exhibit. An admin attempts to execute a shell script located in /tmp but gets 'Permission denied'. Which mount option is most likely causing this?
⚠ Common exam trap
Many exam-takers assume 'Permission denied' always means missing execute bits (chmod +x), when in fact the noexec mount option silently blocks execution even with correct permissions.
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
✓
noexec
The 'noexec' mount option prevents execution of any binary or script directly from the filesystem, regardless of file permissions. Since the script is in /tmp and the admin gets 'Permission denied' despite correct execute bits, the /tmp partition is likely mounted with noexec, which is a common security hardening practice.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
relatime
Why it's wrong here
relatime only controls when access timestamps are written to disk; it has no bearing on execute permission. It tempts because it is a common /etc/fstab option, so it appears in the same configuration context as the noexec option that actually blocks script execution.
- ✓
noexec
Why this is correct
The `noexec` mount option prevents execution of any binaries or scripts on that filesystem, directly causing the "Permission denied" error when running the script from /tmp. Since /tmp is frequently mounted with `noexec` for security hardening, this constraint matches the symptom precisely, whereas other options would produce different errors.
- ✗
nodev
Why it's wrong here
nodev only blocks device-file interpretation; it does not remove execute permission, so it cannot cause 'Permission denied' here. The likely culprit is noexec, which forbids executing binaries from that mount. nodev is tempting because /tmp hardening guides often list it, and it is correct when untrusted device nodes must be ignored.
- ✗
nosuid
Why it's wrong here
nosuid prevents set-user-ID and set-group-ID bits from taking effect; it does not strip execute permission from a script. It tempts because it is a recognised hardening option on /tmp, but noexec is the mount option that produces 'Permission denied' on execution.
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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.