XK0-006 System Management — 30 Questions

Question 1

A user reports that a script in /home/user/script.sh fails to execute. The output of 'ls -l script.sh' is '-rw-r--r-- 1 user user 1024 Apr 1 10:00 script.sh'. Which command should be used to make the script executable for all users?

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

Accepted Answer

chmod a+x script.sh. The current mode `-rw-r--r--` (644) grants read/write to the owner and read-only to group and others, with no execute bit set anywhere. `chmod a+x script.sh` adds the execute bit for user, group, and other (a = ugo), producing `-rwxr-xr-x` (755) and satisfying the requirement that all users can execute the script. It is the most direct, symbolic-mode answer to 'make executable for all users.'

Answer

chmod 644 script.sh

Answer

chmod u+x script.sh

Answer

chmod 755 script.sh

Question 2

A system administrator needs to set the umask so that newly created files have permissions of 644 and directories have permissions of 755. Which umask value should be set?

Accepted Answer

0022. Default base permissions are 666 for files and 777 for directories. To get 644 (rw-r--r--) for files: 666 - 644 = 022. To get 755 (rwxr-xr-x) for directories: 777 - 755 = 022. So umask 022 works for both.

Answer

0222

Answer

000

Answer

077

Question 3

A Linux administrator needs to display the amount of disk space used by each mounted filesystem. Which two commands can be used? (Choose two.)

Accepted Answer

du -h /. Option E, `df -h`, is correct because `df` (disk free) reports the space used and available on each mounted filesystem, and the `-h` flag renders sizes in human-readable units like GB and MB, exactly matching the requirement to show disk space used per mounted filesystem. Option A, `du -h /`, is also correct because `du` (disk usage) with `-h` summarizes the space consumed by files and directories, and running it against `/` reports the amount of disk space used, which satisfies the administrator's goal of seeing usage per filesystem. Option B, `mount | column -t`, only lists mounted filesystems and their mount options in tabular form; it shows no usage figures. Option C, `lsblk`, enumerates block devices and their sizes but does not report used versus free space on mounted filesystems. Option D, `fdisk -l`, displays partition tables and partition sizes, not the amount of space currently used on each mounted filesystem.

Answer

mount | column -t

Answer

lsblk

Answer

fdisk -l

Question 4

An administrator wants to change the runlevel/target to a state where only a minimal set of processes is running, and network services are disabled. Which two systemd targets achieve this? (Choose two.)

Accepted Answer

rescue.target. rescue.target (B) is correct because it starts a single-user-like rescue shell with only a minimal set of services, mounting local filesystems but not activating network services, which matches the requested state. emergency.target (E) is also correct because it provides the most minimal environment, mounting only the root filesystem read-only and starting essentially no services, including no networking. graphical.target (A) is wrong because it starts a full graphical multi-user environment with networking enabled. poweroff.target (C) is wrong because it shuts the system down rather than providing a running minimal state. multi-user.target (D) is wrong because it is the normal multi-user runlevel that includes network services.

Answer

graphical.target

Answer

poweroff.target

Answer

multi-user.target

Question 5

A system administrator wants to ensure a service starts automatically at boot and also starts immediately without rebooting. Which of the following systemctl commands or command combinations achieve both goals? (Choose all that apply.)

Accepted Answer

systemctl start service && systemctl enable service. Option C is correct because it explicitly starts the service immediately with 'systemctl start service' and then enables it for automatic startup at boot with 'systemctl enable service'. Option D is correct because 'systemctl enable --now service' combines both actions in a single command: the '--now' flag starts the service immediately while 'enable' configures it to start at boot. Both achieve the dual goal of immediate start and persistent enablement.

Answer

systemctl enable service && systemctl restart service

Answer

systemctl start --now service

Question 6

An administrator wants to list all files in the current directory that are larger than 1 MB. Which find commands are correct? (Choose two.)

Accepted Answer

find . -type f -size +1M. Both options A and D are syntactically correct and will produce the same result. The find command evaluates expressions in order, but the -type and -size conditions are independent; their order does not affect functionality. Option A (find . -type f -size +1M) specifies file type before size, while option D (find . -size +1M -type f) specifies size before file type. Both are valid because find processes predicates left-to-right, but since -type f filters by file type and -size +1M filters by size, any file that does not satisfy both will be excluded regardless of order.

Answer

find . -type f -size 1M

Answer

find . -type f -size +1MB

Question 7

A Linux administrator needs to find all files in /var/log that have been modified within the last 7 days and are larger than 10 MB. Which find command accomplishes this?

Accepted Answer

find /var/log -mtime -7 -size +10M. The command 'find /var/log -mtime -7 -size +10M' correctly finds files modified within the last 7 days (mtime -7 means less than 7 days ago) and larger than 10 MB (+10M). The alternative 'find /var/log -mmin -10080 -size +10M' also works because 10080 minutes equals 7 days, and -mmin -10080 means modified less than 10080 minutes ago. Both are correct.

Answer

find /var/log -atime -7 -size +10M

Answer

find /var/log -mtime +7 -size -10M

Question 8

An administrator needs to find the line number of the first occurrence of the string 'ERROR' in a log file, ignoring case. Which command is most appropriate?

Accepted Answer

grep -in 'error' logfile. grep -in 'error' logfile will output the line numbers with matches, ignoring case. The first line will be shown first if no other sorting is applied.

Answer

grep -n 'ERROR' logfile

Answer

sed -n '/ERROR/=' logfile

Answer

awk '/ERROR/ {print NR}' logfile

Question 9

A file has permissions rwxr-x--- and is owned by user alice and group devs. Which command would add the SUID bit while preserving existing permissions?

Accepted Answer

chmod u+s file. chmod u+s adds the SUID bit. The symbolic mode 'u+s' sets the SUID without changing the existing permission bits.

Answer

chmod a+s file

Answer

chmod 2755 file

Answer

chmod 4750 file

Question 10

An administrator needs to replace all occurrences of '192.168.1.1' with '10.0.0.1' in a configuration file named config.txt. Which sed command should be used to perform an in-place edit?

Accepted Answer

sed -i 's/192.168.1.1/10.0.0.1/g' config.txt. The `-i` flag tells sed to edit the file in place, and the trailing `g` flag makes the substitution global across every occurrence on each line. Option A combines both requirements — in-place editing plus replacement of all matches — which is exactly what the administrator needs.

Answer

sed -i 's/192.168.1.1/10.0.0.1/' config.txt

Answer

sed -e 's/192.168.1.1/10.0.0.1/g' config.txt

Answer

sed 's/192.168.1.1/10.0.0.1/g' config.txt > config.txt

Question 11

An administrator suspects that a malicious process is running and wants to list all processes, including those without a controlling terminal, and see their full command line. Which two commands can provide this information? (Select TWO.)

Accepted Answer

ps aux. Option C (ps aux) is correct because the BSD-style aux syntax lists every process on the system, including daemons and other processes with no controlling terminal (shown with a '?' in the TTY column), and the 'u' format displays the full command line with arguments for each process. Option D (ps -ef) is correct because the UNIX-style -e flag selects all processes regardless of terminal ownership, and the -f full-format option prints the complete command line (CMD column) along with UID, PID, and PPID, which is exactly what is needed to spot a suspicious process. Option A (lsof) is not correct here because it lists open files and the processes holding them, not a comprehensive process list with full command lines. Option B (ps -eo pid,cmd) is not marked correct because, although it can show all processes and command lines, it is not one of the two answers designated as correct for this scenario. Option E (top -b -n 1) is not correct because top shows a live resource-usage snapshot and truncates or omits full command-line detail, so it does not reliably provide the complete command line for every process.

Answer

lsof

Answer

ps -eo pid,cmd

Answer

top -b -n 1

Question 12

Which three directories are required by the FHS to be present on a Linux system? (Select THREE.)

Accepted Answer

/bin. The Filesystem Hierarchy Standard (FHS) mandates that /bin (option A) exist because it holds essential user command binaries needed for single-user mode and system boot, such as ls, cp, and sh. Option C, /dev, is required because it contains device files (block and character special files) that provide access to hardware and virtual devices like /dev/sda and /dev/null. Option D, /etc, is required as the location for host-specific system configuration files, including /etc/passwd, /etc/fstab, and /etc/hosts, which are essential for system operation. The unmarked options do not belong: /proc (B) is a virtual pseudo-filesystem provided by the kernel at runtime, not a mandatory FHS directory, and /opt (E) is an optional location for add-on application software packages, so it is not required to be present.

Answer

/proc

Answer

/opt

Question 13

A system administrator is troubleshooting a service that fails to start at boot. The system uses systemd. Which of the following commands would the administrator use to check the service's status and view its recent log entries?

Accepted Answer

systemctl status service && journalctl -n 50. 'systemctl status service' displays detailed status of the service, including recent logs. 'journalctl -n 50' shows the last 50 journal entries. Together, they provide both status and recent logs. Option A uses 'systemctl is-active', which only returns active/inactive, not detailed status. Option C lists failed units and error-level logs, not specific to the service. Option D also uses 'systemctl is-active' (boolean) and 'journalctl -n 50' without focusing on the service. Therefore, B is the best choice.

Answer

journalctl -u service -n 50 && systemctl is-active service

Answer

systemctl list-units --state=failed && journalctl -p err

Answer

systemctl is-active service && journalctl -n 50

Question 14

A Linux administrator needs to remove a package installed via RPM and all its configuration files. Which command should the administrator use?

Accepted Answer

rpm -e package. The 'rpm -e package' command erases (uninstalls) the specified package. By default, RPM removes the package's files and, unless the config files are marked as %config(noreplace) and modified, it also removes the associated configuration files during erase. This is the standard command to remove a package and its configuration artifacts.

Answer

rpm -V package

Answer

rpm -e --allmatches package

Answer

rpm -e --nodeps package

Question 15

A process is running with a nice value of 5. The system administrator wants to increase its priority (lower the nice value) to -5 but is not the owner of the process. What must the administrator do first to achieve this?

Accepted Answer

Use renice with root privileges via sudo. The administrator must use renice with root privileges via sudo because lowering a nice value (increasing priority) requires root privileges when the user is not the process owner. The renice command allows changing the nice value of a running process, but only root can decrease the nice value (i.e., increase priority) for processes owned by other users. Without sudo, a regular user cannot set a nice value lower than the current one, even for their own processes, unless they have the CAP_SYS_NICE capability.

Answer

Use renice -n +10

Answer

Use the nice command with -n -5

Answer

Use kill -SIGSTOP to stop the process then restart

Question 16

A file has permissions set to 2755. Which special permission is enabled, and what does it do?

Accepted Answer

SGID; new files in the directory inherit the group. The permission 2755 includes the SGID (Set Group ID) special permission, indicated by the leading digit '2'. When SGID is set on a directory, new files and subdirectories created within it inherit the group ownership of the directory, rather than the primary group of the user who creates them. This is critical for collaborative environments where multiple users need shared group access.

Answer

No special permission; it is just octal 755

Answer

Sticky bit; only file owners can delete their files

Answer

SUID; the file runs with the owner's privileges

Question 17

After making changes to /etc/grub.d/ and /etc/default/grub, an administrator needs to regenerate the GRUB2 configuration file. Which command should be used?

Accepted Answer

grub2-mkconfig -o /boot/grub2/grub.cfg. After modifying /etc/grub.d/ scripts or /etc/default/grub, the GRUB2 configuration file must be regenerated to apply the changes. The command `grub2-mkconfig -o /boot/grub2/grub.cfg` reads the configuration snippets and defaults, then writes the final boot menu configuration to the specified output file. This is the standard method on RHEL/CentOS 7+ and other distributions using GRUB2.

Answer

grub2-install

Answer

grub2-set-default 0

Answer

update-grub

Question 18

An administrator wants to display only the second field from a colon-delimited file named 'passwd' using a text processing tool. Which command will achieve this?

Accepted Answer

awk -F: '{print $2}' passwd. awk -F: '{print $2}' passwd sets field separator to : and prints second field. cut -d: -f2 also works, but the options include awk. sed is for editing, not field extraction; grep is for pattern matching.

Answer

sed 's/:.*//' passwd

Answer

cut -d: -f2 passwd

Answer

grep -o '^[^:]*:[^:]*' passwd

Question 19

A technician is troubleshooting a service that fails to start. The service file is located in /usr/lib/systemd/system. Which THREE commands can be used to investigate the service's status and logs? (Choose three.)

Accepted Answer

journalctl -u servicename. Option B, journalctl -u servicename, is correct because the -u (unit) filter restricts journal output to messages logged by that specific systemd unit, which is exactly what is needed to read the service's logs. Option C, systemctl status servicename, is correct because it reports the unit's load state, active state, main PID, exit code, and the most recent log lines, making it the primary tool for investigating why a service failed. Option E, journalctl -f, is correct because it follows the journal in real time, letting the technician watch new messages as the service is retried or started, which helps capture the failure output. Option A, systemctl enable servicename, only creates the symlinks for start-at-boot and does not display status or logs. Option D, systemctl start servicename, merely attempts to start the unit and provides no diagnostic status or log output on its own.

Answer

systemctl enable servicename

Answer

systemctl start servicename

Question 20

A system running systemd is failing to boot properly. The administrator wants to boot into an environment with only the essential services for troubleshooting. Which systemd target should be selected at boot?

Accepted Answer

rescue.target. The rescue.target is a systemd target that starts a single-user environment with basic system services, including mounting local file systems and starting a rescue shell. It is designed for troubleshooting when the system cannot boot normally, providing essential services without the full multi-user or graphical environment. This matches the requirement for an environment with only essential services.

Answer

multi-user.target

Answer

emergency.target

Answer

graphical.target