LFCS Essential Commands Practice Question
A system administrator runs 'grep -r 'error' /var/log' and gets many false positives. They want to search only for the exact word 'error' as a whole word, case-insensitively, and display line numbers. Which command should they use?
⚠ Common exam trap
The trap here is that candidates often forget the `-w` flag is needed for whole-word matching, assuming `-i` alone is sufficient, or they confuse the order of flags and omit one of the required options.
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
✓
grep -rwin 'error' /var/log
It combines all required flags: `-r` for recursive search, `-w` for whole-word matching (using word boundaries), `-i` for case-insensitive search, and `-n` for displaying line numbers. The `-w` flag ensures that only the exact word 'error' is matched, not substrings like 'error404' or 'error-prone', which eliminates false positives.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
grep -rwi 'error' /var/log
Why it's wrong here
Missing -n for line numbers.
- ✗
grep -rin 'error' /var/log
Why it's wrong here
No whole word matching.
- ✗
grep -rwn 'error' /var/log
Why it's wrong here
Missing -i for case-insensitivity.
- ✓
grep -rwin 'error' /var/log
Why this is correct
Correct: recursive, whole word, case-insensitive, line numbers.
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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.