Adding SGID to a directory | LinuC Level 1 101 Exam original practice question

1.02.1Basic

Preserve shared's ordinary permissions and add SGID for group inheritance.

Which command is appropriate?

Hint 1: Focus on the requirement

The directory needs the group special bit, while preserving its existing ordinary access permissions.

Hint 2: Key terms

Review the short definitions before comparing the ownership and permission choices.

g+s: Symbolic mode that adds set-group-ID to a directory.
Group execute: The directory x permission that allows members to traverse it.
SGID inheritance: The directory behavior that gives new entries the directory's owning group.
Mode 2775: An example combining SGID with ordinary directory mode 775.

Detailed explanation

Incorrectchmod u+s shared

Incorrect. u+s sets SUID.

Incorrectchmod g+x shared

Incorrect. g+x adds ordinary group execute/search permission only.

Incorrectchmod o+t shared

Incorrect. o+t sets sticky bit.

Correctchmod g+s shared

Correct. chmod g+s shared adds the directory SGID bit.

An example you can run in a temporary verification environment.

tmp=$(mktemp -d); chmod 775 "$tmp"; chmod g+s "$tmp"; stat -c '%A %a' "$tmp"; chmod 700 "$tmp"; rmdir "$tmp"

drwxrwsr-x 2775

Environment: GNU coreutils 9.x / 一時ディレクトリ
Use a disposable file or directory when checking chmod calculations.
Exact permission display can vary slightly with filesystem and distribution defaults.

Foundation review

g+s sets group inheritance; group write and execute permissions determine whether collaboration is usable.

Check both the special bit and the directory's group ownership before creating shared content.

Question IDKL-101-388

EnvironmentGNU coreutils 9.x / 一時ディレクトリ

Last technical review2026-08-13

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