performance
medium
Apply
pipeline-distinct
2 points
Question 38. CSCD240-E1-A
Count distinct lines in visitors.txt (unsorted input).
Work the drill
Answer on paper or in a terminal before revealing the ideal answer.
Ideal answer
sort visitors.txt | uniq | wc -l
Acceptable alternatives: ["sort -u visitors.txt | wc -l", "cat visitors.txt | sort -u | wc -l"]
Misconception bank
Each row below is a plausible wrong answer, the thinking that produces it, and the remedy that corrects the misconception. These are the foundation of the multiple-choice framing and the targeted feedback a student receives after answering.
uniq visitors.txt | wc -l
Misconception. uniq without sort collapses only adjacent duplicates.
Remedy. Golden rule: always sort BEFORE uniq.
wc -l visitors.txt
Misconception. Counts ALL lines, not distinct.
Remedy. Read the question: distinct vs total.
Authority mappings
Hover any chip for the mapping justification; click to open the authority record.
DCWF roles:
CS-511 Cyber Defense Analyst
DCWF tasks:
T0259
O*NET tasks:
SOC 15-1212.00: task 6SOC 15-1212.00: task 7SOC 15-1244.00: task 1SOC 15-1244.00: task 2
NCAE errors:
SSH Login / failure: Failed to connect to host: IPSSH Login / partial: The following users failed t.SSH Login / partial: The following users failed t.
Course-artifact links
Lectures
- CSCD240-S26-L08. Pipes, filters, grep, sort, uniq, wc, tar
Lab questions
- CSCD240-S26-LAB4: Build pipeline: sort words.txt | uniq -c | sort -rn | head. Top-N frequency.