Quick Answer
The answer is systemctl stop myapp.service, systemctl kill myapp.service, and systemctl restart myapp.service. These three commands directly alter the service's runtime state: stop transitions it from active to inactive by gracefully terminating the main process, kill sends a signal (default SIGTERM) to the main process which can force termination or state change, and restart combines a stop followed by a start, effectively resetting the service’s state. On the Linux Foundation Certified System Administrator LFCS exam, this question tests your understanding of systemd’s state management versus commands that only modify configuration or reload units without affecting a currently running process. A common trap is confusing systemctl reload (which only re-reads config files without stopping the service) or systemctl daemon-reload (which scans for unit changes) with commands that actually change the running state. Remember the mnemonic “Kill, Stop, Restart — three ways to change a running heart.”
This LFCS practice question tests your understanding of service configuration. 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.
Which THREE actions will affect the state of a systemd service that is currently running? (Choose three.)
systemctl kill myapp.service
Sends a signal to the service process.
systemctl reload myapp.service
Reloads configuration without restarting.
systemctl disable myapp.service
Why wrong: Disables the service from starting at boot; does not affect current running state.
systemctl daemon-reload
Why wrong: Reloads unit files, but does not modify running services.
systemctl stop myapp.service
Stops the running service.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
systemctl kill myapp.service
Option A is correct because `systemctl kill myapp.service` sends a signal (default SIGTERM) to the main process of the running service, which can terminate or alter its state. This directly changes the service from a running state to a stopped or failed state depending on the signal and process behavior.
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.
systemctl kill myapp.service
Why this is correct
Sends a signal to the service process.
Related concept
Read the scenario before looking for a memorised answer.
systemctl reload myapp.service
Why this is correct
Reloads configuration without restarting.
Related concept
Read the scenario before looking for a memorised answer.
systemctl disable myapp.service
Why it's wrong here
Disables the service from starting at boot; does not affect current running state.
systemctl daemon-reload
Why it's wrong here
Reloads unit files, but does not modify running services.
systemctl stop myapp.service
Why this is correct
Stops the running service.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
The trap here is that candidates often confuse `disable` (which only affects future boots) with `stop` (which affects the current runtime state), or think `daemon-reload` immediately impacts running services when it only updates unit definitions for subsequent operations.
Detailed technical explanation
Under the hood, `systemctl kill` uses the `sd_pid_notify()` mechanism or direct `kill()` syscall to send signals to the service's control group (cgroup). The `reload` action sends SIGHUP or executes a custom reload command defined in the unit file's `ExecReload` directive, which allows the service to re-read configuration without a full restart. The `stop` action sends SIGTERM followed by SIGKILL after a timeout (default 90 seconds), transitioning the unit to the 'inactive' state.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Real-world example
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
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FAQ
Service Configuration — This question tests Service Configuration — Read the scenario before looking for a memorised answer..
The correct answer is: systemctl kill myapp.service — Option A is correct because `systemctl kill myapp.service` sends a signal (default SIGTERM) to the main process of the running service, which can terminate or alter its state. This directly changes the service from a running state to a stopped or failed state depending on the signal and process behavior.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Read the scenario before looking for a memorised answer.
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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.
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