XK0-006 Automation, Orchestration, and Scripting Practice Test 11 — 15 Questions

Question 1

A Linux administrator is using Git to manage a configuration repository. They need to undo a commit that has already been pushed to a shared remote repository, without rewriting history. Which command should they use?

Choose an answer to begin — your selection is scored in the full session.

Accepted Answer

git revert <commit>. To undo a commit that has already been pushed without rewriting history, `git revert` is the correct choice. It creates a new commit that reverses the changes, preserving the original commit in the history. This is safe for collaboration because it does not require force pushing. Other commands like `reset`, `commit --amend`, or `rebase` rewrite history and should be avoided in shared repositories.

Answer

git rebase -i <commit>

Answer

git reset --hard <commit>

Answer

git commit --amend

Question 2

A Linux administrator needs a scheduled task to run a backup script at 02:30 every day of the week. The system uses cron, and the administrator is editing the crontab for the `backup` user. Which crontab entry accomplishes this?

Accepted Answer

30 2 * * * /usr/local/bin/backup.sh. A standard crontab line places minute first, then hour, day-of-month, month, and day-of-week. The requested 02:30 daily schedule requires minute 30 and hour 2 with asterisks in the remaining fields. Transposing the time fields, restricting the day of month, or leaving the minute as a wildcard all produce schedules that do not run the backup once daily at the intended time.

Answer

2 30 * * * /usr/local/bin/backup.sh

Answer

30 2 1 * * /usr/local/bin/backup.sh

Answer

* 2 * * * /usr/local/bin/backup.sh

Question 3

An administrator is writing a Bash script that must run a cleanup function when the script exits, whether it finishes normally or is interrupted. Which construct guarantees the function runs in both cases?

Accepted Answer

trap 'cleanup' EXIT. The trap facility lets a script associate a handler with a signal or with the EXIT pseudo-signal, which the shell raises on every termination path. Using trap 'cleanup' EXIT ensures the teardown function executes after normal completion and after interrupts, unlike aliases, backgrounding, or plain sequential execution, which have no exit semantics.

Answer

cleanup &

Answer

set -e; cleanup

Answer

alias cleanup='rm -rf /tmp/work'

Question 4

A Linux administrator is troubleshooting a Bash script that must parse each line of a file named `servers.txt` and process fields separated by colons. The script currently uses `for line in $(cat servers.txt)` and breaks on lines containing spaces. Which construct should replace the loop to correctly iterate over lines while preserving whitespace?

Accepted Answer

while IFS= read -r line; do ... done < servers.txt. Reading lines reliably requires disabling word splitting and backslash processing with `IFS= read -r line`, and attaching the input redirection to the `while` loop so the loop does not run in a subshell. Piping into the loop loses variable state, command substitution splits on whitespace, and placing the redirection on the `read` command reopens the file on each iteration instead of advancing through it.

Answer

for line in $(< servers.txt); do ... done

Answer

cat servers.txt | while read line; do ... done

Answer

while read -r line < servers.txt; do ... done

Question 5

A Linux administrator needs to run a recurring backup script located at /usr/local/bin/backup.sh every day at 02:30. The system uses systemd and the administrator wants the job scheduled through a systemd timer rather than cron. Which combination of unit files must be created and enabled?

Accepted Answer

A .timer unit with OnCalendar=*-*-* 02:30:00 and a matching .service unit, then enable and start the .timer unit.. A systemd timer requires two cooperating units: a .timer unit that defines the schedule via OnCalendar= and a same-named .service unit that defines what to execute. To activate the schedule you enable and start the .timer unit, not the service. At each matching calendar point systemd triggers the associated service, which runs the ExecStart= command pointing at the backup script.

Answer

A single .service unit containing OnCalendar=*-*-* 02:30:00 in its [Service] section, then enable and start that unit.

Answer

A .timer unit with OnCalendar=*-*-* 02:30:00 and a matching .service unit, then enable and start the .service unit.

Answer

A .timer unit with OnBootSec=02:30 and a matching .service unit, then enable and start the .timer unit.

Question 6

A Linux administrator is writing a Bash script that processes a list of hostnames stored one per line in /etc/app/hosts.list. The script must read each line into the variable host and run a command against it, and the loop must not consume standard input from the terminal so that interactive commands inside the loop can still read from the keyboard. Which construct satisfies these requirements?

Accepted Answer

while IFS= read -r host <&3; do probe "$host"; done 3< /etc/app/hosts.list. Redirecting the list to an alternate file descriptor and reading with read <&3 keeps standard input attached to the terminal, so interactive commands invoked in the loop body can still prompt the user. Using IFS= read -r also preserves hostname characters verbatim, which the whitespace-splitting for loop and the stdin-consuming while form cannot guarantee.

Answer

for host in $(cat /etc/app/hosts.list); do probe "$host"; done

Answer

until read host; do probe "$host"; done < /etc/app/hosts.list

Answer

while read -r host; do probe "$host"; done < /etc/app/hosts.list

Question 7

A Linux administrator is writing a systemd unit file at /etc/systemd/system/backup.service that must execute /usr/local/bin/backup.sh only after the network is fully reachable and the /mnt/archive mount is active. The unit currently has no ordering directives. Which directive should be added to the [Unit] section to satisfy this requirement?

Accepted Answer

After=network-online.target local-fs.target. Ordering in systemd is expressed with After= and Before=, which control when a unit is queued relative to others without creating a dependency. To guarantee the backup script runs only once the network is up and /mnt/archive is mounted, the [Unit] section needs After=network-online.target local-fs.target. Dependency keywords such as Requires, Wants, and BindsTo pull units in or tie lifecycles together but never enforce start ordering on their own.

Answer

Wants=network-online.target local-fs.target

Answer

Requires=network-online.target local-fs.target

Answer

BindsTo=network-online.target local-fs.target

Question 8

A Linux administrator is automating container builds and needs to reduce image size and ensure reproducibility. Which TWO practices should be applied when writing the Dockerfile? (Choose two.)

Accepted Answer

Pin base images and package versions to specific tags or digests. Image size and reproducibility are improved by minimizing layers and pinning inputs. Combining install and cleanup in one RUN prevents deleted cache files from persisting in earlier layers, and pinning base images and package versions ensures identical builds. Using mutable tags, splitting update from install, or copying the full context early all work against these goals.

Answer

Add a separate RUN apt-get update in every RUN instruction that installs packages

Answer

Copy the entire build context into the image with COPY . /app before installing dependencies

Answer

Use the `latest` tag for all base images to always receive security updates

Question 9

A configuration-management playbook run by an administrator must install the nginx package only on hosts whose inventory group is webservers, and must restart the nginx service whenever the package installation changes the system. The administrator is using Ansible. Which pair of task attributes achieves both the conditional execution and the conditional restart?

Accepted Answer

Use when: "'webservers' in group_names" on the install task and a notify: directive referencing a handler that restarts nginx.. Ansible conditionals evaluate Jinja2 expressions against host facts and magic variables. group_names is a list of the inventory groups containing the current host, so testing membership restricts the install to webservers hosts. The notify: attribute links a task to a handler; handlers are deferred and fire only when the notifying task returns changed, which is exactly the behavior needed to restart nginx solely after a real package change.

Answer

Use when: "inventory_hostname == 'webservers'" on the install task and a notify: directive referencing a handler that restarts nginx.

Answer

Use tags: webservers on the install task and a notify: directive referencing a handler that restarts nginx.

Answer

Use when: "'webservers' in group_names" on the install task and a changed_when: true attribute that restarts nginx.

Question 10

A Linux administrator uses Ansible to manage a fleet of servers and needs to ensure a configuration file is present with specific contents on all web servers, restarting the service only when the file changes. Which Ansible module and handler pattern accomplishes this?

Accepted Answer

Use the `copy` module with a `notify` directive that triggers a handler containing the `service` module with `state: restarted`. Idempotent configuration management requires a module that reports change status and a handler that reacts to that status. The `copy` module writes the file and reports changed only on difference, and the `notify` directive invokes a handler that restarts the service. Unconditional shell restarts, `force: no`, or timestamp-only modules all fail to deliver a restart triggered specifically by a content change.

Answer

Use the `file` module with `state: touch` and a `cron` job to restart the service periodically

Answer

Use the `template` module with `force: no` and no handler, relying on the service to reload automatically

Answer

Use the `shell` module to run `systemctl restart httpd` after writing the file with a `command` task

Question 11

A Linux administrator is writing a Bash script that processes a list of filenames stored one per line in a file. Some filenames contain spaces. The administrator wants the loop to treat each full line as a single item without word-splitting, and also wants to strip the trailing newline from each item. Which construct accomplishes this?

Accepted Answer

while IFS= read -r line; do process "$line"; done < filelist. Reading lines safely in Bash requires neutralizing both whitespace trimming and escape processing. IFS= preserves the line exactly, and -r stops backslashes from acting as escapes. Quoting the variable at every use prevents a second round of word splitting. Only the construct that combines all three elements keeps filenames with spaces or special characters as single, unmodified arguments.

Answer

while read line; do process "$line"; done < filelist

Answer

while IFS= read -r line; do process $line; done < filelist

Answer

for line in $(cat filelist); do process "$line"; done

Question 12

An administrator is building a container image and needs to reduce its final size while keeping the build reproducible. Which TWO practices improve image efficiency and build reliability? (Choose two.)

Accepted Answer

Combine related RUN instructions and clean package caches within the same layer.. Image efficiency hinges on layer mechanics: files removed in a later layer still occupy the earlier one, so cleanup must happen in the same RUN that created the mess. Reproducibility hinges on locked inputs, so base images and packages should be referenced by exact version or digest rather than a moving tag. Combining those two disciplines yields smaller, repeatable builds.

Answer

Add a .dockerignore file that excludes the local .git directory and build artifacts.

Answer

Use multiple FROM instructions to layer several base images into one final image.

Answer

Set the ENV HOME variable to a writable path so package managers cache downloads there.

Question 13

A Linux administrator needs to schedule a script at /opt/scripts/report.sh to run every Monday at 02:30 for the user svcacct, without editing the system-wide /etc/crontab. Which cron entry correctly accomplishes this when placed in svcacct's crontab via crontab -e?

Accepted Answer

30 2 * * 1 /opt/scripts/report.sh. Cron's five fields are minute, hour, day of month, month, and day of week, in that order. The requirement of Monday at 02:30 maps to minute 30, hour 2, wildcard day of month, wildcard month, and day-of-week 1 for Monday. Placing the entry in svcacct's own crontab via crontab -e means it executes as that user without needing a username field or touching /etc/crontab.

Answer

2 30 * * 1 /opt/scripts/report.sh

Answer

30 2 * * 0 /opt/scripts/report.sh

Answer

30 2 1 * * /opt/scripts/report.sh

Question 14

A Linux administrator needs a cron job that runs /usr/local/bin/collect.sh at 02:30 every Monday, Wednesday, and Friday. The job must be added for the root user without editing the global /etc/crontab file. Which command should the administrator run to open the correct crontab for editing?

Accepted Answer

crontab -u root -e. The crontab command with the -u option edits the named user's personal crontab, so crontab -u root -e reliably opens root's schedule for modification from any account with the needed privilege. The schedule line 30 2 * * 1,3,5 then executes collect.sh at 02:30 on Monday, Wednesday, and Friday, fulfilling the requirement without touching /etc/crontab.

Answer

crontab -l -u root

Answer

systemctl edit cron

Answer

crontab -e

Question 15

A Linux administrator writes a Bash script that processes a list of hostnames read from a file and must continue processing remaining hosts even if an SSH command to one host fails. The script currently uses set -e and exits on the first failure. Which change allows the loop to keep running while still exiting on other unhandled errors?

Accepted Answer

Append || true to the SSH command inside the loop.. Bash's errexit option does not trigger on commands whose failure is consumed by a logical construct. Because the shell checks the exit status of the entire AND-OR list, appending || true to the SSH invocation means the list returns zero even when SSH fails, so the loop continues. Other commands in the script remain protected by set -e, preserving the desired fail-fast behavior elsewhere.

Answer

Wrap the SSH command in a subshell with parentheses.

Answer

Replace set -e with set +e globally.

Answer

Redirect stderr to /dev/null on the SSH command.