XK0-006 Practice Test 43 — 15 Questions

Question 1

In a Bash script, which THREE of the following are valid ways to define a function? (Select THREE.)

Accepted Answer

Answer

myfunc = () { commands; }

Answer

def myfunc { commands; }

Question 2

An Apache web server (httpd) is serving content from a custom directory /webapps/company. The root directory is labeled with the default_t context, causing httpd to be denied access. Which command should the administrator use to persistently relabel the directory for httpd access?

Accepted Answer

semanage fcontext -a -t httpd_sys_content_t '/webapps/company(/.*)?'. `semanage fcontext` modifies the SELinux file context policy persistently, and the regex `/webapps/company(/.*)?` ensures the rule applies to the directory and all its contents. This is necessary because `restorecon` (option A) only applies the default context from the policy, which is `default_t` for this custom path, and `chcon` (option B) is non-persistent and will be overwritten by a file system relabel. The `setsebool` (option C) controls a boolean for user content, not the file context of a custom directory.

Answer

restorecon -v /webapps/company

Answer

chcon -t httpd_sys_content_t /webapps/company

Answer

setsebool -P httpd_read_user_content on

Question 3

An administrator wants to ensure a service starts automatically at boot on a systemd-based system. Which command should be used?

Accepted Answer

systemctl enable service. systemctl enable sets the service to start automatically at boot.

Answer

systemctl start service

Answer

systemctl status service

Answer

systemctl reload service

Question 4

A Linux administrator needs to view the contents of a compressed log file without decompressing it. Which command should be used?

Accepted Answer

zcat. zcat reads compressed files and outputs the contents to stdout without decompressing them to disk.

Answer

cat

Answer

bzcat

Answer

gunzip

Question 5

Which directory in the Filesystem Hierarchy Standard (FHS) contains variable data such as logs and spool files?

Accepted Answer

/var. /var is designated for variable data that changes frequently, such as logs, spool directories, and temporary files.

Answer

/opt

Answer

/etc

Answer

/tmp

Question 6

A user reports that a service fails to start with the error 'Permission denied'. The service runs under a non-root user. Which command should the administrator use to check if the service has the correct file permissions?

Accepted Answer

namei -l /path/to/service. The error 'Permission denied' when starting a service under a non-root user often involves not just the file's own permissions but also the permissions of each directory in the path leading to the service binary. The `namei -l` command recursively lists the permissions of every component in the path, revealing if any parent directory lacks execute (search) permission for the service user, which would block access even if the binary itself is correctly set. This makes it the most comprehensive tool for diagnosing path-based permission issues.

Answer

ls -l /path/to/service

Answer

getfacl /path/to/service

Answer

stat /path/to/service

Question 7

A Linux server with systemd is experiencing boot issues after a recent kernel update. Which command sequence should be used to boot into the previous kernel version?

Accepted Answer

Interrupt the boot process, select 'Advanced options' in GRUB, then choose the previous kernel.. GRUB (Grand Unified Bootloader) stores multiple kernel versions in its menu. By interrupting the boot process and selecting 'Advanced options for Ubuntu' (or similar), you can choose the previous kernel entry, which loads the older kernel and its associated initramfs. This is the standard method to recover from a failed kernel update on systems using systemd and GRUB.

Answer

Boot from a live CD and run 'rpm -Uvh --oldkernel' to revert the kernel.

Answer

Use 'systemctl set-default multi-user.target' and reboot.

Answer

Use 'grub2-set-default' with the previous kernel entry before rebooting.

Question 8

A Linux administrator writes a script that uses bash-specific features like arrays and process substitution. Which shebang should be used?

Accepted Answer

#!/bin/bash. The correct shebang is #!/bin/bash because the script uses bash-specific features such as arrays and process substitution. The shebang line tells the system to execute the script with the specified interpreter; /bin/bash is the Bourne Again SHell, which supports these features, while /bin/sh may be a POSIX shell that lacks them.

Answer

#!/bin/sh

Answer

#!/usr/bin/python3

Answer

#!/bin/ksh

Question 9

Which command displays the current default umask value for a user?

Accepted Answer

umask. The umask command without arguments prints the current umask value.

Answer

chmod

Answer

set

Answer

ls -l

Question 10

A container is running a database service that requires persistent storage. The administrator wants to ensure that data persists even if the container is removed. Which volume mount type should be used in the Docker run command?

Accepted Answer

--mount type=volume. Docker volumes are the preferred mechanism for persisting data generated by and used by Docker containers. Volumes are completely managed by Docker, are independent of the container lifecycle, and can be backed up easily. They persist even after the container is removed, making them ideal for database services. While bind mounts (option B) also provide persistence by mapping a host directory, they are less portable and have security considerations. Since the question does not specify a need for host directory mapping, volumes are the recommended choice.

Answer

--mount type=bind

Answer

COPY in Dockerfile

Answer

--mount type=tmpfs

Question 11

An administrator runs 'rpm -V httpd' and sees output like 'S.5....T. /etc/httpd/conf/httpd.conf'. What does this indicate?

Accepted Answer

The file has been modified since installation. The rpm -V command verifies installed packages. The output shows that the file size, MD5 checksum, and modification time have changed from the package's original.

Answer

The file has been deleted

Answer

The file has incorrect permissions

Answer

The file is corrupted

Question 12

Based on the exhibit, what is the most likely cause of the sshd service failure?

Accepted Answer

The privilege separation directory /var/empty/sshd does not exist.. The error message 'Privilege separation directory /var/empty/sshd does not exist' directly indicates that the required chroot directory for the unprivileged sshd process is missing. Without this directory, sshd cannot drop privileges after authentication, causing it to fail on startup. This is a common issue after a partial installation or cleanup of OpenSSH.

Answer

The SSH configuration file has a syntax error.

Answer

The sshd PID file cannot be written.

Answer

The SSH port is already in use by another service.

Question 13

A user wants to view the contents of a text file one page at a time. Which two commands can be used? (Choose two.)

Accepted Answer

less. less and more are pagers that display content one screen at a time.

Answer

cat

Answer

tail

Answer

head

Question 14

An administrator needs to permanently disable a systemd service from starting at boot. Which two commands can achieve this? (Choose two.)

Accepted Answer

systemctl disable servicename. systemctl disable and systemctl mask both prevent a service from starting at boot, but mask also prevents manual start.

Answer

systemctl stop servicename

Answer

systemctl kill servicename

Answer

systemctl unmask servicename

Question 15

A technician wants to extract the third column of a tab-separated file and sort the output uniquely. Which three commands can be combined using pipes to achieve this? (Choose three.)

Accepted Answer

cut -f3. cut extracts columns, sort sorts them, uniq removes duplicates. tee would write to file and stdout, not needed.

Answer

tee

Answer

wc -l