This LPIC-1 practice question tests your understanding of gnu and unix commands. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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 THREE of the following are correct features of the 'grep' command? (Choose three.)
-i makes the search case-insensitive
Correct: --ignore-case.
-v inverts the match
Correct: --invert-match.
-c counts matching lines
Correct: --count.
-l prints line numbers of matches
Why wrong: -l lists filenames with matches, not line numbers.
-r enables regular expression matching
Why wrong: -r enables recursive directory search; grep uses basic regex by default.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
-i makes the search case-insensitive
Option A is correct because the `-i` flag in `grep` performs case-insensitive matching, so patterns like 'error' will match 'Error', 'ERROR', etc. This is a common requirement when searching log files where case may vary.
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.
-i makes the search case-insensitive
Why this is correct
Correct: --ignore-case.
Related concept
Read the scenario before looking for a memorised answer.
-v inverts the match
Why this is correct
Correct: --invert-match.
Related concept
Read the scenario before looking for a memorised answer.
-c counts matching lines
Why this is correct
Correct: --count.
Related concept
Read the scenario before looking for a memorised answer.
-l prints line numbers of matches
Why it's wrong here
-l lists filenames with matches, not line numbers.
-r enables regular expression matching
Why it's wrong here
-r enables recursive directory search; grep uses basic regex by default.
Common exam traps
The trap here is that candidates confuse `-l` (list filenames) with `-n` (show line numbers) and assume `-r` enables regex, when in fact `-r` is for recursive directory traversal and regex is the default behavior.
Detailed technical explanation
The `grep` command uses the POSIX regular expression engine; `-i` works by converting both the pattern and input to a common case before comparison, which can be slightly slower on large files. In real-world scenarios, combining `-i` with `-v` (invert match) is useful for filtering out case-insensitive noise, such as excluding all lines containing 'debug' regardless of capitalization.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
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FAQ
GNU and Unix Commands — This question tests GNU and Unix Commands — Read the scenario before looking for a memorised answer..
The correct answer is: -i makes the search case-insensitive — Option A is correct because the `-i` flag in `grep` performs case-insensitive matching, so patterns like 'error' will match 'Error', 'ERROR', etc. This is a common requirement when searching log files where case may vary.
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 25, 2026
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.
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