Writing nested command substitution clearly | LinuC Level 1 102 Exam original practice question

1.06.1Basic

Pass pwd output to basename and store only the current directory name in CURRENT_DIR.

Use a syntax with clear nested delimiters.

Which assignment is appropriate?

Hint 1: Focus on shell scope

Separate login and non-login shells, interactive behavior, current-shell changes, and command expansion before comparing the choices.

Hint 2: Key terms

Review the short definitions of the shell files, process boundaries, and expansion rules involved.

Command substitution: A shell feature that embeds one command's output in another command or value.
Nested substitution: A substitution placed inside another so the inner result becomes outer input.
pwd: A command that writes the current working-directory path to standard output.
basename: A command that extracts the final component of a path.
Double quotes: Quoting that permits expansion while preventing expanded whitespace from splitting words.

Detailed explanation

IncorrectCURRENT_DIR='basename pwd'

Incorrect. It assigns literal text and executes neither command.

IncorrectCURRENT_DIR=$(pwd basename)

Incorrect. It passes basename as an argument to pwd in the wrong order.

IncorrectCURRENT_DIR=${basename ${pwd}}

Incorrect. This is not a valid nested parameter-expansion form.

CorrectCURRENT_DIR=$(basename "$(pwd)")

Correct. The inner pwd result is passed to the outer basename command.

An example you can run in a temporary verification environment.

bash --noprofile --norc -c 'cd /tmp; CURRENT_DIR=$(basename "$(pwd)"); printf "%s\n" "$CURRENT_DIR"'

tmp

Foundation review

A substitution placed inside another so the inner result becomes outer input.

A command that extracts the final component of a path.

Quoting that permits expansion while preventing expanded whitespace from splitting words.

Question IDKL-102-906

EnvironmentGNU Bash 5.2 / /tmpへ移動する一時シェル

Last technical review2026-08-13

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