Matching one or more repetitions | LPIC-1 101-500 Exam original practice question

103.7Basic

Extract lines that start with a, contain one or more b characters, and end with c.

Use grep extended regular expressions.

Which command is appropriate?

Hint 1: Focus on the requirement

Identify what must change and what must remain unchanged. Then choose the command whose scope matches that requirement.

Hint 2: Check each command's role

Separate commands that display information, change state, remove data, or affect a child process.

grep -E '^ab*c$' tokens.txt: Incorrect. * also matches abc with zero b characters, which violates the requirement.
grep -E '^ab?c$' tokens.txt: Incorrect. ? allows zero or one b, not one or more.
grep -F '^ab+c$' tokens.txt: Incorrect. -F treats the expression as literal text.
grep -E '^ab+c$' tokens.txt: Correct. -E enables + and the anchors require the complete line.

Detailed explanation

Incorrectgrep -E '^ab*c$' tokens.txt

Incorrect. * also matches abc with zero b characters, which violates the requirement.

Incorrectgrep -E '^ab?c$' tokens.txt

Incorrect. ? allows zero or one b, not one or more.

Incorrectgrep -F '^ab+c$' tokens.txt

Incorrect. -F treats the expression as literal text.

Correctgrep -E '^ab+c$' tokens.txt

Correct. -E enables + and the anchors require the complete line.

An example you can run in a temporary verification environment.

printf '%s\n' ac abc abbc abdc | grep -E '^ab+c$'

abc
abbc

Foundation review

Check whether the command acts on the current shell, a new process, an existing process, or a file.

Use the supplied command and compare the output with the expected result.

Question IDKP-103-104

EnvironmentGNU grep 3.x / LC_ALL=C

Last technical review2026-08-12