LFCS Essential Commands Practice Question
A developer reports that a compiled binary 'app' fails to execute with 'Permission denied' error when run from a mounted directory '/mnt/software'. The binary has execute permissions for all users. What is the most likely cause?
⚠ Common exam trap
It's easy for candidates to assume 'Permission denied' always relates to file permissions (chmod) or SELinux, but the LFCS exam tests knowledge of mount options like 'noexec' which silently override file-level permissions at the filesystem level.
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
✓
The filesystem is mounted with the 'noexec' option.
The 'noexec' mount option prevents execution of any binary files on the filesystem, regardless of their file permissions. When a filesystem is mounted with 'noexec', the kernel will refuse to execute binaries from that mount point, returning 'Permission denied' even if the binary has execute permissions for all users. This is a common security measure for mounted directories like /mnt/software to prevent unauthorized code execution.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
SELinux is blocking execution.
Why it's wrong here
SELinux would generate an AVC denial, not a simple 'Permission denied'.
- ✗
The binary is linked against missing libraries.
Why it's wrong here
Missing libraries produce a different error message.
- ✓
The filesystem is mounted with the 'noexec' option.
Why this is correct
The 'noexec' mount option prevents execution of binaries.
- ✗
The binary is setuid but owned by a user other than root.
Why it's wrong here
Setuid without root ownership is ignored but does not cause 'Permission denied'.
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This LFCS question is part of Courseiva's 507-question bank — original exam-style content with full explanations and wrong-answer analysis, never real exam questions or exam dumps. Learn why practice questions differ from exam dumps →
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.