This LFCS practice question tests your understanding of essential 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.
To display the first 10 lines of a file named 'log.txt', which command is correct?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "first"
Why it matters: Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
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.
less log.txt
Why wrong: Opens the file in a pager; does not automatically show only first 10 lines.
tail log.txt
Why wrong: Shows the last 10 lines by default.
head log.txt
Outputs the first 10 lines by default.
cat log.txt
Why wrong: Outputs the entire file.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
head log.txt
The `head` command is designed to display the first 10 lines of a file by default. Running `head log.txt` outputs the first 10 lines of the file without any additional options, making it the correct choice for this task.
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.
less log.txt
Why it's wrong here
Opens the file in a pager; does not automatically show only first 10 lines.
tail log.txt
Why it's wrong here
Shows the last 10 lines by default.
head log.txt
Why this is correct
Outputs the first 10 lines by default.
Clue confirmation
The clue words "first", "which command" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
cat log.txt
Why it's wrong here
Outputs the entire file.
Common exam traps
The trap here is that candidates often confuse `head` with `tail` or assume `less` or `cat` are appropriate for displaying only the first few lines, when in fact `head` is the specific command for that purpose.
Trap categories for this question
Command / output trap
Opens the file in a pager; does not automatically show only first 10 lines.
Detailed technical explanation
The `head` command reads the file from the beginning and outputs the specified number of lines (default 10) by using buffered I/O to efficiently read the file. It is part of the GNU coreutils and is often used in pipelines to preview data, such as `head -n 20 log.txt` to show the first 20 lines. A subtle behavior is that `head` can also be used with the `-c` option to output the first N bytes instead of lines, which is useful for binary files or fixed-size records.
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 LFCS 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
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Essential Commands — study guide chapter
Learn the concepts, then practise the questions
Essential Commands practice questions
Targeted practice on this topic area only
All LFCS questions
513 questions across all exam domains
Linux Foundation Certified System Administrator LFCS study guide
Full concept coverage aligned to exam objectives
LFCS practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Practise LFCS questions linked to User and Group Management.
Practise LFCS questions linked to Operation of Running Systems.
Practise LFCS questions linked to Essential Commands.
Practise LFCS questions linked to Networking.
Practise LFCS questions linked to Service Configuration.
Practise LFCS questions linked to Storage Management.
Practise LFCS questions linked to LFCS fundamentals.
Practise LFCS questions linked to LFCS scenario.
Practise LFCS questions linked to LFCS troubleshooting.
Practice this exam
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
Essential Commands — This question tests Essential Commands — Read the scenario before looking for a memorised answer..
The correct answer is: head log.txt — The `head` command is designed to display the first 10 lines of a file by default. Running `head log.txt` outputs the first 10 lines of the file without any additional options, making it the correct choice for this task.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Yes — watch for: "first", "which command". Order matters here. You are being tested on which action comes before the others — not which action is generally useful.
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Last reviewed: Jun 25, 2026
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.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.