XK0-005 Practice Test 14 — 15 Questions

Question 1

Refer to the exhibit. An administrator is troubleshooting an issue where services cannot write log files. Based on the output, which filesystem is most likely the cause?

Accepted Answer

/dev/sda1 (/). The output shows that the root filesystem /dev/sda1 mounted on / is at 100% usage. Since log files are typically written under /var/log, which resides on the root partition unless /var is a separate mount point, a full root filesystem prevents services from writing log files. The correct answer is D because the root filesystem is full, causing the write failures.

Answer

/dev/sda3 (/home)

Answer

Swap partition

Answer

/dev/sda2 (/var)

Question 2

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?

Accepted Answer

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.

Answer

Use -d flag to run in detached mode

Answer

Restart the container with --restart=always

Answer

Allocate a pseudo-TTY with -t flag

Question 3

A script named 'test.sh' contains '#!/bin/bash' and is located in the current directory. Which command runs the script in the current shell environment without forking a subshell?

Accepted Answer

source test.sh. The `source` command (or its synonym `.`) executes the script in the current shell environment without forking a subshell. This is essential when you need the script to modify the current shell's environment, such as setting variables or changing directories, because a subshell would discard those changes upon exit.

Answer

./test.sh

Answer

sh test.sh

Answer

bash test.sh

Question 4

You are a Linux system administrator for a small company. You have written a BASH script that checks disk usage and sends an email alert if any partition exceeds 90% usage. The script works when run manually but does not produce alerts when run via cron. Which of the following is the most likely cause?

Accepted Answer

The cron job's PATH variable does not include the directory where the mail command is located. When a script runs manually, it inherits the user's interactive shell environment, including the PATH variable that typically includes directories like /usr/bin and /usr/local/bin where the mail command resides. However, cron jobs execute in a minimal environment with a very restricted PATH (often just /usr/bin:/bin). If the mail command is located in a directory not in cron's default PATH, such as /usr/sbin or /opt/bin, the script will fail silently when attempting to send the email, even though the disk usage check itself succeeds. This is the most common cause of scripts working manually but failing under cron.

Answer

The script has incorrect file permissions

Answer

The cron scheduler is disabled

Answer

The script uses relative paths to check partitions

Question 5

A DevOps engineer is designing a CI/CD pipeline for a microservices application. The pipeline should build a Docker image, run unit tests, and if successful, push the image to a private registry. Which tool is best suited for orchestrating this pipeline?

Accepted Answer

Jenkins. Jenkins is a widely adopted CI/CD automation server that excels at orchestrating complex pipelines, including building Docker images, running unit tests, and pushing images to a private registry. Its pipeline-as-code feature (Jenkinsfile) allows defining stages, triggers, and post-build actions, making it the best fit for this microservices CI/CD workflow.

Answer

Git

Answer

cron

Answer

Ansible

Question 6

Which two of the following are valid methods to pass environment variables to a Docker container at runtime? (Select TWO.)

Accepted Answer

Defining variables in a .env file and using --env-file. Option A is correct because the `--env-file` flag in `docker run` allows you to pass environment variables from a file (typically a `.env` file) to the container at runtime. This method is useful for managing multiple variables without cluttering the command line and supports variable substitution and quoting rules as defined by Docker.

Answer

Using the ENV instruction in the Dockerfile

Answer

Using the export command inside the container

Answer

Using the ARG instruction in the Dockerfile

Question 7

Which THREE of the following are valid ways to define environment variables in a Docker container? (Choose three.)

Accepted Answer

Passing with docker run -e VAR=value. Option A is correct because the `docker run -e VAR=value` syntax directly sets an environment variable inside the container at runtime. This overrides any ENV instruction in the Dockerfile for that specific run, giving the operator flexibility without modifying the image.

Answer

Using the ARG instruction in Dockerfile

Question 8

Refer to the exhibit. A Docker container using a bind mount fails to start with a permission error. What is the most likely cause?

Accepted Answer

SELinux is blocking the mount.. When a Docker container uses a bind mount and fails with a permission error, SELinux is a common cause because it enforces mandatory access controls that can block container processes from accessing host files. By default, SELinux labels container processes with a confined domain (e.g., container_t), and if the bind-mounted host directory lacks the proper SELinux context (e.g., container_file_t), the mount is denied. This is resolved by adding the `:Z` or `:z` flag to the bind mount in the Docker run command to relabel the host directory appropriately.

Answer

The container is running in privileged mode.

Answer

The Docker daemon is not running as root.

Answer

The volume path on the host does not exist.

Question 9

Which command will create a compressed tar archive of a directory?

Accepted Answer

tar -czf archive.tar.gz dir. Option A is correct because the `-czf` flags combine `-c` (create archive), `-z` (compress with gzip), and `-f` (specify archive file name). This creates a compressed tar archive of the specified directory, outputting a `.tar.gz` file. The command `tar -czf archive.tar.gz dir` is the standard syntax for this operation.

Answer

tar -xzf archive.tar.gz

Answer

tar -cf archive.tar dir

Answer

tar -tf archive.tar

Question 10

A junior administrator writes a bash script to check disk usage and send an email alert. The script runs manually but does not execute from cron. Which of the following is the most likely cause?

Accepted Answer

Absolute path not specified in crontab. When a script runs manually from the command line but fails from cron, the most common cause is that cron does not inherit the user's PATH environment. Without an absolute path to the script in the crontab entry, cron cannot locate the script. Option D directly addresses this: specifying the full path (e.g., /home/user/script.sh) ensures cron can find and execute it.

Answer

Script not marked executable

Answer

Incorrect file permissions on cron job

Answer

Missing shebang line

Question 11

A sysadmin is tasked with creating a script that will run only on weekdays at 9:00 AM using cron. The script should not run on holidays. Which approach best achieves this requirement?

Accepted Answer

Use cron to run at 9:00 on weekdays, and include a test in the script that checks a holiday list. Option B is correct because cron can schedule the script to run at 9:00 AM on weekdays using the day-of-week field (e.g., `0 9 * * 1-5`), and the script itself can check a holiday list (e.g., a file or API) to exit early on holidays. This approach cleanly separates scheduling from holiday logic, avoiding cron's lack of built-in holiday awareness.

Answer

Use systemd timers with a calendar specification that excludes holidays

Answer

Use cron to run at 9:00 every day, and include conditional logic to abort on weekends

Answer

Use `at` to schedule the job individually each weekday morning

Question 12

Which command will show the environment variables for a specific process?

Accepted Answer

cat /proc/$PID/environ. The `/proc/[PID]/environ` file contains the environment variables that were set when the process was started. Reading this file with `cat` displays the exact environment of a specific process, which is not possible with shell built-ins or user-level commands that only show the current shell's environment.

Answer

set

Answer

printenv

Answer

env

Question 13

The script in the exhibit runs successfully but the administrator expects it to indicate success. What change should be made?

Accepted Answer

Change 'exit 1' to 'exit 0'. The script uses 'exit 1' to terminate, which indicates a failure or error condition to the shell. The administrator expects the script to indicate success, so the exit code must be changed to 'exit 0', which is the standard Unix/Linux convention for successful execution. Exit codes are how scripts communicate their status to the calling process, and only exit 0 means success.

Answer

Replace $system_info with just system_info

Answer

Change the variable name to SYSTEM_INFO

Answer

Change 'exit 1' to 'exit 0' and remove the quotes around $system_info

Question 14

Which shebang ensures maximum portability across systems for a Python script?

Accepted Answer

#!/usr/bin/env python3. Option A is correct because `#!/usr/bin/env python3` uses the `env` utility to locate the `python3` interpreter in the user's `PATH`, making the script portable across different Unix-like systems where Python 3 may be installed in various directories (e.g., `/usr/bin/python3`, `/usr/local/bin/python3`). This shebang avoids hardcoding an absolute path, which is the key to maximum portability.

Answer

#!/bin/python

Answer

#!/usr/bin/python

Answer

#!/usr/local/bin/python3

Question 15

A security audit reveals that the /etc/shadow file has permissions 0644 and is owned by root:shadow. The auditor states that this is a security risk because any local user can read password hashes. The administrator wants to fix the permissions to ensure that only root and the shadow group can read the file, and no one else can read it. Additionally, the administrator wants to set the immutable attribute on the file to prevent accidental modification. Which set of commands achieves the desired state?

Accepted Answer

chmod 640 /etc/shadow; chattr +i /etc/shadow. Option A is correct because chmod 640 sets the file permissions to read/write for root (owner) and read-only for the shadow group, while removing all access for others. chattr +i sets the immutable attribute, which prevents any modifications (including deletion, renaming, or content changes) even by root until the attribute is removed. This satisfies the requirement that only root and the shadow group can read the file, and no one else can read it, while also protecting against accidental modification.

Answer

chmod 640 /etc/shadow; chattr +a /etc/shadow

Answer

chmod 640 /etc/shadow; chmod +i /etc/shadow

Answer

chmod 600 /etc/shadow; chattr +i /etc/shadow

XK0-005 Practice Test 14 — 15 Questions

Exhibit

XK0-005 Practice Test 14 — 15 Questions

Exhibit