The correct command is echo "0 23 * * * /usr/local/bin/backup.sh" | crontab -, because it pipes the cron schedule directly into the crontab utility, which reads from standard input and installs the job. The cron expression 0 23 * * * precisely targets 11:00 PM every night, with the minute field set to zero and the hour field set to 23, ensuring the backup script runs exactly once per day at the required time. On the CompTIA Linux+ XK0-005 exam, this question tests your ability to schedule nightly backup with cron using the correct syntax and input method; a common trap is confusing crontab -e (which opens an editor) with crontab - (which accepts piped input), or misplacing the minute and hour fields. Remember the cron field order: minute, hour, day of month, month, day of week—so for 11 PM, think “zero minutes, 23 hours.” A useful memory tip is “23 is the hour for 11 PM in 24-hour time, and zero keeps it on the hour.”
XK0-005 Scripting, Containers and Automation Practice Question
This XK0-005 practice question tests your understanding of scripting, containers and automation. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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 junior administrator is asked to automate the backup of a configuration file every night at 11 PM. The script /usr/local/bin/backup.sh already exists. Which command should the administrator run to schedule this task?
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.
Option C is correct because the `crontab -` command reads from standard input and installs the cron job. The line `0 23 * * * /usr/local/bin/backup.sh` specifies that the script should run at 23:00 (11 PM) every day, matching the requirement exactly. This is the standard method for scheduling recurring tasks in Linux using cron.
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.
✗
systemctl start backup.timer
Why it's wrong here
This starts a systemd timer unit named backup.timer, which does not exist by default and would require prior setup.
✗
at 23:00 /usr/local/bin/backup.sh
Why it's wrong here
The at command schedules a one-time execution, not recurring daily.
Correct. This appends a cron job entry to the crontab, scheduling the script to run daily at 23:00.
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.
✗
nohup /usr/local/bin/backup.sh &
Why it's wrong here
This runs the script immediately in the background with nohup, not scheduling it for later.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often confuse `at` (for one-time tasks) with `cron` (for recurring tasks), or assume `systemctl start` can create a timer on the fly without a pre-existing timer unit file.
Trap categories for this question
Command / output trap
The at command schedules a one-time execution, not recurring daily.
Detailed technical explanation
How to think about this question
Cron uses five time-and-date fields (minute, hour, day of month, month, day of week) to define when a command runs. The `crontab -` command replaces the current user's crontab with the input provided, so piping the echo output installs the job. A common pitfall is forgetting that `crontab -e` is interactive, while `crontab -` is non-interactive and suitable for scripting.
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: echo "0 23 * * * /usr/local/bin/backup.sh" | crontab - — Option C is correct because the `crontab -` command reads from standard input and installs the cron job. The line `0 23 * * * /usr/local/bin/backup.sh` specifies that the script should run at 23:00 (11 PM) every day, matching the requirement exactly. This is the standard method for scheduling recurring tasks in Linux using cron.
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: "which command". Tests specific CLI syntax. Recall the exact command and its required context — near-synonyms and partial matches are common distractors.
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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