XK0-006 System Management Practice Question

A user needs to view the first 15 lines of a large log file. Which command is most appropriate?

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

✓

head -n 15 filename

head -n 15 filename displays the first 15 lines of a file.

Answer analysis

For each option: why learners choose it and why it is or isn't the right answer here.

✓
head -n 15 filename
Why this is correct
Correct: head -n 15 shows the first 15 lines.
✗
cat filename | head -n 15
Why it's wrong here
The pipeline `cat filename | head -n 15` works correctly but is unnecessarily inefficient: `head` can open the file directly, so the extra `cat` process adds a redundant read and pipe overhead without any benefit. It is tempting because many users habitually pipe `cat` into other commands as a generic pattern for feeding file content into a filter, and in scenarios where the file must be processed by multiple commands in sequence (e.g., `cat file | grep pattern | sort`), the `cat` is justified as the initial input source.
✗
less -N 15 filename
Why it's wrong here
less does not limit lines by default; -N shows line numbers.
✗
tail -n 15 filename
Why it's wrong here
tail shows the last lines, not the first.

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