This EX200 practice question tests your understanding of essential tools. 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.
A system administrator needs to view the last 10 lines of the log file /var/log/messages in real time as new lines are added. Which command should be used?
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.
tail -f /var/log/messages
tail -f outputs the last 10 lines and updates in real time.
less /var/log/messages
Why wrong: less allows scrolling but does not auto-update.
head -n 10 /var/log/messages
Why wrong: head shows the first 10 lines, not last.
cat /var/log/messages
Why wrong: cat displays the entire file but does not follow updates.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
tail -f /var/log/messages
The `tail -f /var/log/messages` command displays the last 10 lines of the file by default and then continues to output new lines as they are appended, providing real-time monitoring. The `-f` (follow) option keeps the file open and polls for changes, making it the correct tool for live log watching.
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.
tail -f /var/log/messages
Why this is correct
tail -f outputs the last 10 lines and updates in real time.
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.
less /var/log/messages
Why it's wrong here
less allows scrolling but does not auto-update.
head -n 10 /var/log/messages
Why it's wrong here
head shows the first 10 lines, not last.
cat /var/log/messages
Why it's wrong here
cat displays the entire file but does not follow updates.
Common exam traps
Red Hat often tests the distinction between `tail -f` and `tail` without `-f`, where candidates mistakenly think `tail` alone provides real-time updates, or confuse `head` and `tail` for viewing the end of a file.
Trap categories for this question
Command / output trap
head shows the first 10 lines, not last.
Detailed technical explanation
The `tail -f` command uses inotify (on Linux) or polling to detect file changes, outputting new data as it is written. This is essential for monitoring system logs like `/var/log/messages` where the kernel and services continuously append entries. In a real-world scenario, an administrator troubleshooting a service crash would use `tail -f` to see error messages as they occur, avoiding the need to repeatedly rerun `cat` or `less`.
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 EX200 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 Tools — study guide chapter
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Essential Tools practice questions
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FAQ
Essential Tools — This question tests Essential Tools — Read the scenario before looking for a memorised answer..
The correct answer is: tail -f /var/log/messages — The `tail -f /var/log/messages` command displays the last 10 lines of the file by default and then continues to output new lines as they are appended, providing real-time monitoring. The `-f` (follow) option keeps the file open and polls for changes, making it the correct tool for live log watching.
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 30, 2026
This EX200 practice question is part of Courseiva's free Red Hat 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 EX200 exam.
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