Quick Answer
The correct answer is `nohup sleep 100 &` because `nohup` makes a process immune to the SIGHUP signal, which is automatically sent to background processes when the parent shell exits during logout. By prepending `nohup` and appending `&`, the command runs in the background and continues executing even after you close the terminal or log out of an SSH session, with standard output automatically redirected to `nohup.out`. On the Linux Foundation Certified System Administrator LFCS exam, this question tests your understanding of process management and signal handling—specifically how to keep a process running after logout without using tools like `screen` or `tmux`. A common trap is forgetting the `&` or assuming `bg` alone suffices, but `bg` only resumes a stopped job in the current shell session; it does not protect against SIGHUP. Remember the mnemonic: “No Hangup, No Problem”—`nohup` ignores the hangup signal so your process lives on after you log off.
This LFCS practice question tests your understanding of essential 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.
An administrator wants to ensure that a background process continues running after logout. Which command should be used to start the process?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "which command"
Why it matters: Tests specific CLI syntax. Recall the exact command and its required context — near-synonyms and partial matches are common distractors.
nohup sleep 100 &
nohup ignores SIGHUP, so process continues after logout.
runproc sleep 100 &
Why wrong: Not a valid command.
sleep 100 &
Why wrong: Runs in background but will be terminated on logout.
sleep 100 & disown
Why wrong: Does remove job from shell's job control, but SIGHUP may still be sent if not handled; nohup is preferred.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
nohup sleep 100 &
The correct answer is A because `nohup` allows a process to ignore the SIGHUP signal that is sent to background processes when the parent shell exits, ensuring it continues running after logout. The `&` places the command in the background, and `nohup` redirects output to `nohup.out` by default, making it the standard way to run a process immune to hangups.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
nohup sleep 100 &
Why this is correct
nohup ignores SIGHUP, so process continues after logout.
Clue confirmation
The clue word "which command" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
runproc sleep 100 &
Why it's wrong here
Not a valid command.
sleep 100 &
Why it's wrong here
Runs in background but will be terminated on logout.
sleep 100 & disown
Why it's wrong here
Does remove job from shell's job control, but SIGHUP may still be sent if not handled; nohup is preferred.
Common exam traps
The trap here is that candidates often think `&` alone or `disown` alone is sufficient to keep a process running after logout, but without `nohup`, the process will still receive SIGHUP and terminate when the shell exits.
Trap categories for this question
Command / output trap
Not a valid command.
Detailed technical explanation
Under the hood, `nohup` works by calling the `signal()` system call to set the disposition of SIGHUP to SIG_IGN before executing the command, and it also redirects stdin from `/dev/null` to prevent the process from reading from a terminal that no longer exists. A subtle behavior is that `nohup` only protects against SIGHUP; if the process is killed by SIGTERM or SIGKILL, it will still terminate. In real-world scenarios, `nohup` is commonly used for long-running scripts or server processes that must survive SSH session disconnections.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
A practitioner preparing for the LFCS exam encounters this exact type of scenario on the job. The correct answer here is not the most general option — it is the best answer for the specific constraint described. Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option. Real exam questions reward reading the full scenario before eliminating options, because the constraint defines which answer fits.
What to study next
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Essential Commands — study guide chapter
Learn the concepts, then practise the questions
Essential Commands practice questions
Targeted practice on this topic area only
All LFCS questions
513 questions across all exam domains
Linux Foundation Certified System Administrator LFCS study guide
Full concept coverage aligned to exam objectives
LFCS practice test guide
How to use practice tests most effectively before exam day
Related practice questions
Use these pages to review the topic behind this question. This is how one missed question becomes focused revision.
Practise LFCS questions linked to User and Group Management.
Practise LFCS questions linked to Operation of Running Systems.
Practise LFCS questions linked to Essential Commands.
Practise LFCS questions linked to Networking.
Practise LFCS questions linked to Service Configuration.
Practise LFCS questions linked to Storage Management.
Practise LFCS questions linked to LFCS fundamentals.
Practise LFCS questions linked to LFCS scenario.
Practise LFCS questions linked to LFCS troubleshooting.
Practice this exam
Short sessions build daily habit. Longer sessions build exam-day stamina. Try a timed session to simulate real conditions.
FAQ
Essential Commands — This question tests Essential Commands — Read the scenario before looking for a memorised answer..
The correct answer is: nohup sleep 100 & — The correct answer is A because `nohup` allows a process to ignore the SIGHUP signal that is sent to background processes when the parent shell exits, ensuring it continues running after logout. The `&` places the command in the background, and `nohup` redirects output to `nohup.out` by default, making it the standard way to run a process immune to hangups.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Yes — watch for: "which command". Tests specific CLI syntax. Recall the exact command and its required context — near-synonyms and partial matches are common distractors.
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 →
Keep practising
Last reviewed: Jun 11, 2026
This LFCS practice question is part of Courseiva's free Linux Foundation 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 LFCS 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.