LPIC-1 GNU and Unix Commands Practice Question
Which TWO of the following commands output the total number of lines in a file?
⚠ Common exam trap
Candidates often think `grep -c '.'` counts all lines, but it actually excludes empty lines, while `nl` outputs numbered lines rather than a single total count.
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
✓
sed -n '$='
The `sed -n '$='` command prints the line number of the last line of the file, which is equivalent to the total number of lines. The `wc -l` command counts the number of newline characters, which directly gives the total line count. Both commands output the total number of lines in a file.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
grep -c '.'
Why it's wrong here
grep -c '.' counts lines that contain at least one character (non-empty lines).
- ✗
nl
Why it's wrong here
nl numbers all lines but does not output a total count.
- ✗
head -n 1
Why it's wrong here
head -n 1 prints the first line, not the total count.
- ✓
sed -n '$='
Why this is correct
sed -n '$=' prints the line number of the last line, equivalent to the total line count.
- ✓
wc -l
Why this is correct
wc -l counts lines (newline characters).
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