The answer is to modify the Dockerfile to use CMD ["sh"] instead of CMD ["echo", "hello"]. This is correct because a Docker container exits immediately when its main process (PID 1) finishes; the echo command prints a message and terminates, causing the container to stop. By switching to CMD ["sh"], the container runs an interactive shell that waits indefinitely for input, keeping the process alive and the container running. On the CompTIA Linux+ XK0-005 exam, this scenario tests your understanding that containers are ephemeral by design—they live only as long as their entry point process. A common trap is assuming a minimal image will stay alive on its own; the key is ensuring the CMD or ENTRYPOINT launches a long-running or blocking process. Memory tip: "If your container quits, your CMD must sit"—use a shell or a command like `tail -f /dev/null` to keep PID 1 active.
XK0-005 Scripting, Containers and Automation Practice Question
This XK0-005 practice question tests your understanding of scripting, containers and automation. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 system administrator is troubleshooting a Docker container that exits immediately after starting. The container is built from a minimal image that runs a short-lived command. Which change will keep the container running?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "immediately / without restart"
Why it matters: Time or reboot constraint — the correct answer must take effect right away without requiring a reboot or reload.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Modify the Dockerfile to use CMD ["sh"] instead of CMD ["echo", "hello"]
Option A is correct because the container exits immediately when its main process finishes. By changing the CMD from `["echo", "hello"]` (which prints a message and exits) to `["sh"]`, the container runs an interactive shell that waits for input, keeping the process alive and the container running. In Docker, a container lives only as long as its PID 1 process runs.
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.
✓
Modify the Dockerfile to use CMD ["sh"] instead of CMD ["echo", "hello"]
Why this is correct
Running a shell as the main process will keep the container running indefinitely.
Clue confirmation
The clue word "immediately / without restart" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
Use -d flag to run in detached mode
Why it's wrong here
Detached mode does not prevent the process from exiting; it just runs in the background.
✗
Restart the container with --restart=always
Why it's wrong here
This will keep restarting the container but it will still exit immediately each time, causing a continuous restart loop.
✗
Allocate a pseudo-TTY with -t flag
Why it's wrong here
Allocating a TTY alone does not keep the container running; the process must still be long-lived.
Common exam traps
Common exam trap: answer the scenario, not the keyword
CompTIA often tests the misconception that detached mode (`-d`) or restart policies (`--restart=always`) can keep a container running indefinitely, but the core requirement is that the container's main process must not terminate.
Detailed technical explanation
How to think about this question
Docker containers run as isolated processes on the host; PID 1 inside the container is the entrypoint or command. When that process terminates (e.g., after `echo` writes to stdout), the kernel sends a SIGCHLD to the container runtime, which then stops the container. Using a long-running process like `sh` (or `tail -f /dev/null`) ensures PID 1 stays alive. In production, a common pattern is to use a process manager like `tini` or `supervisord` to handle signals and keep the container running.
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 practitioner preparing for the XK0-005 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.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this XK0-005 question in full detail.
Scripting, Containers and Automation — This question tests Scripting, Containers and Automation — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Modify the Dockerfile to use CMD ["sh"] instead of CMD ["echo", "hello"] — Option A is correct because the container exits immediately when its main process finishes. By changing the CMD from `["echo", "hello"]` (which prints a message and exits) to `["sh"]`, the container runs an interactive shell that waits for input, keeping the process alive and the container running. In Docker, a container lives only as long as its PID 1 process runs.
What should I do if I get this XK0-005 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Are there clue words in this question I should notice?
Yes — watch for: "immediately / without restart". Time or reboot constraint — the correct answer must take effect right away without requiring a reboot or reload.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
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Question Discussion
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