The correct choice is the snippet that runs `pre_backup_cmd`, then checks its exit status with `if [ $? -ne 0 ]`, logs an error to stderr, and exits with code 1 before proceeding to `backup_cmd`. This works because `$?` captures the exit code of the immediately preceding command—a zero means success, any non-zero means failure. By testing `$? -ne 0`, the script ensures the backup only runs if the pre-backup step completed without error, which is exactly how you check exit status before continuing in a Bash script. On the CompTIA Linux+ XK0-005 exam, this pattern tests your understanding of conditional execution and error handling in automation scripts; a common trap is forgetting to redirect the error message to stderr with `>&2` or using `exit 1` to signal failure to the calling process. Remember the mnemonic: “Check the question mark before you embark”—always inspect `$?` right after the command whose status you need, or it will be overwritten.
XK0-005 Scripting, Containers and Automation Practice Question
This XK0-005 practice question tests your understanding of scripting, containers and automation. Examine the command output carefully: the correct answer depends on what the output actually shows, not on general recall alone. 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 Linux administrator is writing a Bash script to automate the backup of a database. The script must run a pre-backup command, check its exit status, and if successful, proceed with the backup; otherwise, log an error and exit. Which code snippet correctly implements this logic?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
pre_backup_cmd
if [ $? -ne 0 ]; then echo 'Error' >&2; exit 1; fi
backup_cmd
Option C correctly runs the pre-backup command, then checks its exit status with `$?`. If the exit status is not zero (indicating failure), it logs an error to stderr and exits with code 1. Only if the pre-backup command succeeds does the script proceed to the backup command. This matches the requirement exactly: check exit status, log error on failure, and exit.
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.
✗
set -e
pre_backup_cmd
backup_cmd
Why it's wrong here
set -e exits on any error but does not allow custom logging, and it may exit prematurely without proper handling.
✗
pre_backup_cmd && backup_cmd || echo 'Error' >&2
Why it's wrong here
Using && and || has pitfalls; if backup_cmd fails, it also triggers the error message, which is not intended.
✓
pre_backup_cmd
if [ $? -ne 0 ]; then echo 'Error' >&2; exit 1; fi
backup_cmd
Why this is correct
This correctly captures the exit status of the pre_backup_cmd and handles failure before proceeding.
Related concept
Read the scenario before looking for a memorised answer.
✗
(pre_backup_cmd; if [ $? -ne 0 ]; then echo 'Error' >&2; exit 1; fi) && backup_cmd
Why it's wrong here
The subshell prevents the exit from stopping the main script, and the error handling is flawed.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often choose option B because they think `&&` and `||` provide equivalent conditional logic, but they overlook that the `||` will also catch failures from the backup command itself, not just the pre-backup command, violating the requirement.
Detailed technical explanation
How to think about this question
In Bash, `$?` holds the exit status of the last foreground command, where 0 means success and any non-zero value indicates an error. The `if [ $? -ne 0 ]` construct explicitly tests this value, allowing precise control flow. Using `set -e` (option A) is a common alternative but lacks the ability to log a custom error message before exiting. In real-world automation, logging the exact failure reason to stderr (using `>&2`) is critical for debugging and integration with monitoring systems.
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: pre_backup_cmd
if [ $? -ne 0 ]; then echo 'Error' >&2; exit 1; fi
backup_cmd — Option C correctly runs the pre-backup command, then checks its exit status with `$?`. If the exit status is not zero (indicating failure), it logs an error to stderr and exits with code 1. Only if the pre-backup command succeeds does the script proceed to the backup command. This matches the requirement exactly: check exit status, log error on failure, and exit.
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.
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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