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multiple_choice medium Remember octal-special 2 points

Question 18. CSCD240-E1-C

chmod 4755 /opt/app/runner — which bit was set?

Work the drill

Answer on paper or in a terminal before revealing the ideal answer.

Ideal answer
B: setuid

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.

A: setgid
Misconception. setgid is 2xxx, not 4xxx.
Remedy. 4-2-1: 4=setuid, 2=setgid, 1=sticky.
C: sticky
Misconception. Sticky is 1xxx.
Remedy. 4-2-1 mnemonic.
D: none, only 755 applied
Misconception. The leading 4 IS the setuid bit.
Remedy. Read 4-digit mode carefully.

Authority mappings

Hover any chip for the mapping justification; click to open the authority record.

DCWF tasks: T0250
KU outcomes: CO-M10-O1
NCAE errors: SMB Read / failure: SMB operation failed: [Errno .SMB Read / partial: SMB operation failed: Failed .SMB Read / failure: SMB operation failed: [Errno .

Course-artifact links

Lectures

  • CSCD240-S26-L06. Permissions part 2: chmod octal + symbolic, directory x bit