XK0-006 System Management Practice Question

Answer analysis

Option-by-option breakdown

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

  head outputs the beginning of a file, and -n 15 limits that output to exactly 15 lines, directly satisfying the requirement to view the first 15 lines. tail would show the end, and cat would dump the entire large log.

• ✗

  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 -N numbers every displayed line; the 15 is not a line count, so the file opens at line one without limiting output to 15 lines. It is tempting because less is the standard pager for browsing large files, and would be correct if the user wanted to page through the whole log with line numbers.

• ✗

  tail -n 15 filename

  Why it's wrong here

  tail prints the last lines of a file, so it returns the final 15 entries of the log rather than the first 15 the user requested. It is tempting because tail is the natural tool for reading recent log activity, and would be correct if the user needed the most recent entries instead.

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