This LPIC-1 practice question tests your understanding of gnu and unix commands. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A script uses 'set -e' and then executes 'grep pattern file'. If the pattern is not found, the script exits. Which of the following modifications would prevent the script from exiting while still allowing detection of the pattern's absence?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
set +e; grep pattern file; exit_code=$?; set -e
Option B is correct because it temporarily disables 'set -e' with 'set +e', runs the grep command, captures its exit code in a variable, then re-enables 'set -e'. This allows the script to continue executing after a non-zero exit from grep, while still preserving the exit code for later conditional checks. The other options either fail to preserve the exit code or do not prevent the script from exiting under 'set -e'.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✗
grep -q pattern file || true
Why it's wrong here
The '|| true' makes the command always succeed, hiding the failure.
✓
set +e; grep pattern file; exit_code=$?; set -e
Why this is correct
Temporarily disables exit-on-error, captures exit code, then re-enables.
Related concept
Read the scenario before looking for a memorised answer.
✗
grep pattern file; exit_code=$?
Why it's wrong here
The script would exit on grep failure before the assignment to exit_code.
✗
grep pattern file | head -1
Why it's wrong here
set -e still applies to the pipeline; if grep fails, the whole pipeline fails and exits.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often think '|| true' or piping to another command will both prevent exit and preserve the exit code, but they fail to realize that these constructs either discard the exit code or do not reliably prevent exit under all shell configurations.
Trap categories for this question
Command / output trap
The '|| true' makes the command always succeed, hiding the failure.
Detailed technical explanation
How to think about this question
The 'set -e' option (also known as 'errexit') causes a bash script to exit immediately if any command returns a non-zero exit status, unless the command is part of a condition (e.g., in an 'if' statement) or is followed by '|| true'. However, using '|| true' discards the exit code. The correct pattern is to temporarily disable 'set -e' with 'set +e', run the command, capture the exit code, then re-enable 'set -e'. This is a common idiom in robust shell scripting, especially when dealing with commands like grep that use exit codes to signal success/failure. Note that 'set -e' does not apply to commands in a pipeline's last component in some shells, but bash's behavior can be subtle; the safest approach is the one in option B.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
How this comes up in practice
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
GNU and Unix Commands — This question tests GNU and Unix Commands — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: set +e; grep pattern file; exit_code=$?; set -e — Option B is correct because it temporarily disables 'set -e' with 'set +e', runs the grep command, captures its exit code in a variable, then re-enables 'set -e'. This allows the script to continue executing after a non-zero exit from grep, while still preserving the exit code for later conditional checks. The other options either fail to preserve the exit code or do not prevent the script from exiting under 'set -e'.
What should I do if I get this LPIC-1 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
This LPIC-1 practice question is part of Courseiva's free LPI certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the LPIC-1 exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.