XK0-006 Practice Test 2 — 25 Questions

Question 1

An administrator wants to force a password change for user 'alice' on next login. Which command is appropriate?

Accepted Answer

passwd --expire alice. The `passwd --expire alice` command (equivalent to `passwd -e alice`) immediately expires alice's password by setting the shadow file's last-change date to 0, forcing a password change at her next login. This is the standard Linux mechanism for administrators to force a one-time password reset without disabling the account.

Answer

passwd -l alice

Answer

chage -l alice

Answer

usermod -f alice

Question 2

An administrator is troubleshooting a web server that is running under SELinux enforcing mode. The web content is located in a non-standard directory /webfiles. Using the standard SELinux context 'httpd_sys_content_t', the files are still inaccessible. Which command will properly set the context recursively and persist across relabels?

Accepted Answer

semanage fcontext -a -t httpd_sys_content_t '/webfiles(/.*)?' ; restorecon -Rv /webfiles. `semanage fcontext -a -t httpd_sys_content_t '/webfiles(/.*)?'` adds a file-context mapping to the SELinux policy database, ensuring the context survives a `restorecon` or filesystem relabel. The subsequent `restorecon -Rv /webfiles` applies that context recursively to the directory. Without the `semanage` entry, `restorecon` alone would revert to the default context (often `default_t`), which is not accessible by httpd.

Answer

chcon -R -t httpd_sys_content_t /webfiles

Answer

setenforce 0

Answer

restorecon -Rv /webfiles

Question 3

An administrator needs to add a script to be executed daily. The script is placed at /etc/cron.daily/myscript. After placing the script, it does not run. Based on the exhibit, what is the most likely issue?

Accepted Answer

The script is not executable. Scripts placed in /etc/cron.daily/ are executed by run-parts, which requires files to have the executable bit set. Without the execute permission (e.g., chmod +x), the script is skipped entirely, even if it is owned correctly and the cron daemon is active.

Answer

The script is owned by the wrong user

Answer

The cron daemon is not running

Answer

The script is not listed in /etc/crontab

Answer

Anacron is not installed

Question 4

Which TWO of the following are valid methods for debugging a Bash script? (Choose TWO.)

Accepted Answer

Run the script with 'bash -x script.sh'. Running 'bash -x script.sh' enables an execution trace that prints each command and its arguments to stderr before executing it, which is a standard debugging method for Bash scripts. Option C is correct because adding 'set -x' at the start of the script achieves the same trace output, but from within the script itself, allowing granular control over which sections are traced.

Answer

Add 'set -r' to restrict shell

Answer

Run the script with 'bash -d script.sh'

Answer

Add 'set -n' to check syntax

Question 5

A system administrator wants to schedule a script to run every Monday at 3 AM. Which cron entry is correct?

Accepted Answer

0 3 * * 1 /path/to/script.sh. The cron syntax for 'at 3 AM every Monday' is minute 0, hour 3, day-of-month *, month *, and day-of-week 1 (where 0 and 7 both represent Sunday, and 1 represents Monday). This matches the required schedule exactly.

Answer

0 3 1 * * /path/to/script.sh

Answer

3 0 * * 1 /path/to/script.sh

Answer

0 3 * * 2 /path/to/script.sh

Question 6

A user reports that a custom application service fails to start with a 'Permission denied' error in the logs. The service runs under the 'appuser' account. Which is the most likely cause and the first step to diagnose?

Accepted Answer

SELinux is blocking the service; check journalctl for AVC denials and use restorecon or setsebool.. SELinux enforces mandatory access controls that can block a service from starting even when standard Linux file permissions are correct. The 'Permission denied' error, combined with the service running under a non-root user, strongly suggests SELinux is denying access. Checking journalctl for AVC denials is the standard first diagnostic step to confirm SELinux involvement, followed by using restorecon to fix file context labels or setsebool to adjust SELinux booleans.

Answer

The root password is incorrect; change root password with passwd.

Answer

The service binary does not have execute permission for appuser; use chmod +x.

Answer

The systemd target is not set to multi-user; run systemctl set-default multi-user.target.

Question 7

What does the `set -x` command do when placed at the top of a bash script?

Accepted Answer

Displays each command before executing it. `set -x` enables a shell debugging mode that prints each command (after expansion) to stderr before executing it. This is commonly used in bash scripts to trace execution flow and debug complex logic.

Answer

Enables position parameters

Answer

Exits the script on error

Answer

Treats unset variables as errors

Question 8

A technician needs to check the kernel ring buffer for hardware errors detected during system boot. Which command should be used?

Accepted Answer

dmesg. The kernel ring buffer contains messages emitted by the kernel, including hardware detection and error messages during boot. The 'dmesg' command reads and prints this buffer directly. It is the canonical tool for inspecting kernel-level hardware errors, driver initialization failures, and boot-time device detection.

Answer

journalctl -k

Answer

lspci

Answer

cat /var/log/boot.log

Question 9

A system administrator wants to deploy a containerized application on a Linux server with minimal overhead and without a daemon. Which container runtime should be used?

Accepted Answer

Podman. Podman is the correct choice because it is a daemonless container engine that runs containers directly under the user's process space, using a fork-exec model rather than a background daemon. This aligns with the requirement for minimal overhead and no daemon, as Podman does not require a persistent service to manage containers.

Answer

containerd

Answer

LXC

Answer

Docker

Question 10

Match each Linux filesystem to its typical use case.

Accepted Answer

ext4: General-purpose filesystem for Linux desktops and servers. Correct matches: ext4 for general use, XFS for large files, Btrfs for advanced features. Common confusions: swap vs tmpfs where swap is disk-based virtual memory and tmpfs is RAM-based temporary storage.

Answer

swap: Temporary filesystem stored in RAM

Answer

tmpfs: Space on disk used as virtual memory

Question 11

A Linux administrator needs to verify which network interfaces are up and their IP addresses on a server. Which command provides this information?

Accepted Answer

ip addr. The `ip addr` command displays all network interfaces along with their IP addresses, MAC addresses, and status (UP/DOWN).

Answer

ss -tlnp

Answer

nmcli dev show

Answer

ifconfig -a

Question 12

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. 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

Question 13

Which command is used to query the status of a service managed by systemd?

Accepted Answer

systemctl status servicename. systemctl status shows whether a service is active, enabled, and recent log entries.

Answer

journalctl -u servicename

Answer

service servicename status

Answer

systemctl list-units --type=service

Question 14

Which TWO commands can be used to change the group ownership of a file? (Choose exactly two.)

Accepted Answer

chgrp. Option B (chgrp) is correct because chgrp is the dedicated command for changing a file's group ownership, e.g. 'chgrp developers file.txt' sets the group of file.txt to developers. Option D (chown) is correct because chown can also change group ownership using the ':group' or '.group' syntax, e.g. 'chown :developers file.txt' or 'chown user:developers file.txt'. Option A (chmod) is incorrect because it modifies read/write/execute permission bits (and special bits like setgid), not the owning group itself. Option C (groupmod) is incorrect because it modifies attributes of an existing group in /etc/group, such as its name or GID, not a file's group ownership. Option E (usermod) is incorrect because it modifies user account attributes such as group membership, home directory, or shell, not file ownership.

Answer

chmod

Answer

groupmod

Answer

usermod

Question 15

A Linux system has a directory with permissions drwxr-xr-x. A user in the group 'dev' tries to create a new file inside this directory. Which permission is missing that prevents the user from creating the file?

Accepted Answer

Write permission for the group. The directory has write permission for the owner, but only read and execute for the group. To create a file, the user needs write permission on the directory, which is not granted to the group.

Answer

Write permission for the owner

Answer

Sticky bit is set

Answer

Execute permission for the group

Question 16

Refer to the exhibit. A web application running under Apache cannot write to /var/log/app.log. The file has permissions 664 and is owned by apache. What is the correct action to allow writes while maintaining SELinux policies?

Accepted Answer

Change the SELinux context of the file to httpd_log_t.. The file /var/log/app.log has permissions 664 and is owned by apache, so the web server should be able to write to it. However, SELinux is blocking the write because the file's SELinux context does not match the type expected for files that Apache (httpd) is allowed to write to. Changing the SELinux context to httpd_log_t tells SELinux that this file is a log file that httpd can write to, which resolves the denial while keeping SELinux enforcing.

Answer

Change the ownership to root.

Answer

Set the httpd_can_network_connect boolean.

Answer

Disable SELinux for the httpd daemon.

Question 17

In a Bash script, what is the difference between single quotes and double quotes?

Accepted Answer

Single quotes prevent variable expansion; double quotes allow it.. Single quotes preserve the literal value of each character, while double quotes allow variable expansion and command substitution.

Answer

Both behave the same.

Answer

Single quotes allow variable expansion; double quotes do not.

Answer

Double quotes prevent all substitutions; single quotes allow command substitution.

Question 18

A system administrator is writing a Bash script that must check if a file exists and is readable. Which two test expressions can be used to achieve this? (Choose two.)

Accepted Answer

-e /path/to/file. Option A, `-e /path/to/file`, is correct because the `-e` test in Bash returns true if the file exists, regardless of its type (regular file, directory, device, etc.), which satisfies the existence check. Option C, `-r /path/to/file`, is correct because the `-r` test returns true if the file exists and the current user has read permission on it, satisfying the readability check. Together, `-e` and `-r` cover the two required conditions of existence and readability. Option B, `-s`, only checks that the file exists and has a size greater than zero, so it does not verify readability. Option D, `-x`, checks for execute permission rather than read permission, so it does not meet the requirement. Option E, `-f`, only checks that the path exists and is a regular file, not that it is readable.

Answer

-s /path/to/file

Answer

-x /path/to/file

Answer

-f /path/to/file

Question 19

A Docker container using port 8080 fails to start with the error 'port is already allocated'. Which command should the administrator use to identify the process using that port?

Accepted Answer

ss -tlnp. The `ss -tlnp` command lists TCP listening sockets (`-l`) with numeric addresses (`-n`) and shows the process identifier (PID) and process name (`-p`) that owns each socket. This directly identifies which process has bound port 8080, allowing the administrator to resolve the 'port is already allocated' error.

Answer

ss -tan

Answer

ss -tln

Answer

ss -r

Question 20

A Kubernetes pod has a container that fails with CrashLoopBackOff. The administrator runs 'kubectl logs pod-name' but sees no output. What is the most likely cause?

Accepted Answer

The container exited before writing to stdout, and logs need to be retrieved with 'kubectl logs --previous'.. When a container enters CrashLoopBackOff, it restarts repeatedly. If 'kubectl logs pod-name' shows no output, it means the current (restarted) container has not written anything to stdout yet. The previous instance of the container may have written logs before crashing, and those logs are accessible using 'kubectl logs --previous' to retrieve the output from the terminated container.

Answer

The container has no logging driver configured.

Answer

The log file is rotated and deleted.

Answer

The pod is not scheduled on any node.