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 command is used to compress a file with the highest compression ratio?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "which command"
Why it matters: Tests specific CLI syntax. Recall the exact command and its required context — near-synonyms and partial matches are common distractors.
gzip -9
Why wrong: gzip offers moderate compression, lower than xz.
xz -9
xz offers the highest compression ratio among these tools, especially with -9.
bzip2 -9
Why wrong: bzip2 provides good compression but xz is generally better.
compress
Why wrong: compress is outdated and provides low compression ratios.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
xz -9
Option B is correct because `xz -9` uses the LZMA2 compression algorithm, which typically achieves a higher compression ratio than gzip (DEFLATE) or bzip2 (Burrows-Wheeler transform) at the cost of slower speed and higher memory usage. The `-9` flag sets the highest compression level, maximizing the ratio.
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.
gzip -9
Why it's wrong here
gzip offers moderate compression, lower than xz.
xz -9
Why this is correct
xz offers the highest compression ratio among these tools, especially with -9.
Clue confirmation
The clue word "which command" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
bzip2 -9
Why it's wrong here
bzip2 provides good compression but xz is generally better.
compress
Why it's wrong here
compress is outdated and provides low compression ratios.
Common exam traps
The trap here is that candidates often assume gzip or bzip2 with `-9` offers the highest compression ratio because they are more common, but xz is the correct answer due to its superior LZMA2 algorithm.
Detailed technical explanation
The LZMA2 algorithm in xz uses a dictionary-based approach with a larger sliding window (up to 4 GiB with `-9`) and range encoding, allowing it to exploit long-range redundancies that gzip and bzip2 cannot. In real-world scenarios, xz is preferred for archiving large log files or backups where disk space is critical, but its high memory usage (hundreds of MB for decompression) can be a limitation on embedded systems.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A practitioner preparing for the LPIC-1 exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
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: xz -9 — Option B is correct because `xz -9` uses the LZMA2 compression algorithm, which typically achieves a higher compression ratio than gzip (DEFLATE) or bzip2 (Burrows-Wheeler transform) at the cost of slower speed and higher memory usage. The `-9` flag sets the highest compression level, maximizing the ratio.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Yes — watch for: "which command". Tests specific CLI syntax. Recall the exact command and its required context — near-synonyms and partial matches are common distractors.
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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