Be able to read and set file permissions with umask, find files by size and type, terminate processes with the right signal, and adjust scheduling priority using nice and renice. The single most important thing is knowing which signal or nice value produces the intended effect.
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Domain overview
Domain 3 (System Management) covers Linux process control, job scheduling, storage and filesystem administration, and user/group file access. XK0-006 tests these through scenario questions: interpreting umask results, locating files with find, sending signals via kill and pkill, adjusting priority with nice and renice, and managing services and mounts on a running system.
Exam objectives
Applying umask values to compute default permissions for new files and directories
Using find with -size, -type, and -exec to locate and act on files
Sending signals with kill, pkill, and killall, including SIGKILL and SIGTERM
Changing process priority with nice and renice, and reading it via ps or top
Computing directory permissions by subtracting the umask from 777 incorrectly; directories start at 777, files at 666, and the umask is masked out, not subtracted.
Using kill -9 as a first resort; SIGKILL cannot be caught or cleaned up, so SIGTERM should be tried first unless the process is truly stuck.
Confusing nice values: lower or negative values mean higher priority, and only root can set negative nice values or lower an existing one.
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A Linux administrator needs to locate all files in the /var directory that have been modified within the last 30 minutes and are larger than 10MB. Which command accomplishes this task?
2An administrator wants to grant a specific user, 'jdoe', read and write access to a file that is owned by root:root with permissions 640. The administrator does not want to change the file's owner or group. Which approach should be used?
3A user needs to view the first 15 lines of a large log file. Which command is most appropriate?
4A Linux administrator wants to search for all occurrences of the word 'ERROR' in log files under /var/log, ignoring case, and also print the line numbers. Which command should be used?
5An administrator needs to replace all occurrences of 'oldhost' with 'newhost' in the configuration file /etc/hosts. Which command will perform the replacement and save the changes directly to the file?
6A process with PID 2345 is not responding. The administrator wants to force stop the process immediately. Which command should be used?
7A service called 'myapp' fails to start automatically after a system reboot. The administrator wants to ensure the service starts at boot. Which systemctl command should be used?
8Which directory in the Linux filesystem contains essential user command binaries that are needed for booting and repairing the system?
9An administrator needs to view the last 20 lines of the systemd journal for the 'sshd' service. Which command should be used?
10A system administrator needs to install a package from a local RPM file without resolving dependencies automatically. Which command should be used?
11A user wants to create a hard link to a file. Which three conditions must be true for a hard link to be created successfully? (Choose three.)
12A Linux administrator needs to view the last 10 lines of a log file named 'syslog'. Which command should be used?
13A technician notices a script fails to execute because the user does not have permission. The script currently has permissions 644. The technician needs to add execute permission for the owner only. Which command accomplishes this?
14An administrator wants to find all files in /var/log that have been modified within the last 2 days and have a .log extension. Which command should be used?
15Which command displays the disk usage of files and directories in a human-readable format (e.g., KB, MB)?
16A user reports that they cannot access a file because permission is denied. The file's permissions are -rwsr-xr-x. What special permission is set?
17An administrator needs to replace all occurrences of 'oldhost' with 'newhost' in the file /etc/hosts. Which sed command should be used?
18A Linux engineer is troubleshooting a boot issue. The system boots to a command-line interface but does not start the graphical interface. Which systemd target should be set as default to boot into a graphical environment?
19Which command is used to create a symbolic link named 'link' pointing to the file 'original'?
20A technician needs to kill a process with PID 1234 that is not responding to normal termination. Which command sends SIGKILL?
21Which command displays the number of lines, words, and characters in a file?
22A Linux administrator needs to add an ACL entry to grant read permission to a user named 'jdoe' on a file. Which TWO commands can be used to achieve this? (Select TWO).
23A system administrator is working with compressed files. Which THREE commands can be used to view their contents? (Select THREE).
24A Linux administrator wants to search for the pattern 'ERROR' in all files under /var/log, ignoring case, and display line numbers. Which THREE options should be used with the grep command? (Select THREE).
25Which command is used to display the current process hierarchy in a tree format?
26Given an ACL entry 'u:john:rwx' on a file, which command would remove only the ACL entry for user john without affecting other ACL entries?
27A system administrator wants to change the priority of a running process with PID 1234 to a lower priority (higher nice value). Which command should be used?
28Which of the following directories is defined by the Filesystem Hierarchy Standard (FHS) as containing essential user command binaries that need to be available in single-user mode?
29A technician is troubleshooting a service that fails to start at boot. Which systemctl command should be used to ensure the service starts automatically on subsequent boots?
30Which command is used to display the contents of the systemd journal for a specific unit?
31A technician wants to create a symbolic link in /usr/local/bin that points to /opt/myapp/bin/start.sh. The technician has write permissions to /usr/local/bin. Which command should be used?
32Which command would display the disk usage of each file and directory in /home in a human-readable format, but only showing one level deep?
33A Linux administrator needs to locate all files in the /etc directory that have been modified in the last 24 hours and are not owned by root. Which two commands can be combined to achieve this? (Select TWO.)
34A Linux administrator needs to locate all files in the /var/log directory that have been modified within the last 2 days and contain the word 'error' (case-insensitive). Which command accomplishes this?
35A user wants to change the permissions of a file to give the owner full control, the group read and execute, and others no access. Which of the following chmod commands will achieve this?
36An administrator needs to add an ACL entry to a file that grants the user 'john' read and write permissions. The file currently has no ACLs. Which command should the administrator use?
37Which of the following directories in the Filesystem Hierarchy Standard (FHS) contains variable data files such as logs, spool files, and temporary files that persist across reboots?
38A system administrator wants to view the last 10 lines of a log file and also save those lines to another file for analysis. Which command should the administrator use?
39During the boot process, after the kernel is loaded and the initramfs is executed, which component is responsible for starting the user-space services and managing the system state?
40An administrator wants to find all files in the current directory tree that are larger than 100 MB and have the .log extension. Which find command will accomplish this?
41Which command displays the amount of disk space used and available on mounted filesystems in a human-readable format (e.g., GB, MB)?
42An administrator wants to replace all occurrences of 'oldstring' with 'newstring' in a configuration file named config.cfg, and save the changes. Which sed command should be used?
43A Linux administrator needs to identify which of the following filesystems are journaling filesystems commonly used in Linux. (Choose three.)
44A user has a file with permissions set to 644. Which of the following commands will add the setuid permission to the file? (Choose two.)
45Which of the following commands can be used to display the contents of a file one page at a time? (Choose two.)
46A Linux administrator needs to locate all files in /var/log that were modified more than 7 days ago. Which command should be used?
47A user wants to create a hard link named 'linkfile' to an existing file 'original'. Which command accomplishes this?
48An administrator notices that a service named 'httpd' is not running. They want to check its current status and, if inactive, start it. Which set of systemctl commands should be used?
49Which command displays the amount of free and used disk space on all mounted file systems in a human-readable format?
50An administrator wants to change the default systemd target to multi-user.target so the system boots to a text console. Which command should be used?
51A technician needs to search a log file for lines containing either 'ERROR' or 'FATAL' and display the line numbers. Which command accomplishes this?
52A system administrator runs 'umask 027' in a Bash shell. What will be the default permissions for a new directory created in that shell? (Assume no other umask changes.)
53A process is consuming excessive CPU and needs to be terminated immediately. The PID is 1234. Which command will terminate the process with the most forceful signal?
54Which directory in the Filesystem Hierarchy Standard (FHS) contains essential user commands available to all users, such as 'ls' and 'cp'?
55A Linux administrator needs to view real-time information about running processes, including CPU and memory usage. Which TWO commands can be used for this purpose? (Choose two.)
56An administrator needs to grant read and write access to the 'developers' group on a directory while preserving existing permissions for the owner and others. Which TWO commands can be used to modify ACLs? (Choose two.)
57A Linux administrator needs to change the permissions of a file to be readable and writable by the owner, readable by the group, and no access for others. Which command accomplishes this?
58A system administrator wants to find all files in /var/log that have been modified in the last 7 days and are larger than 100MB. Which command should be used?
59A developer wants to grant a user named 'john' read and write permissions to a file, but the file currently has an ACL that gives 'jane' full control. The administrator wants to add an ACL entry for 'john' without modifying existing entries. Which command accomplishes this?
60Which of the following commands will display the last 10 lines of a log file and also output new lines as they are appended?
61A user wants to run a command that will continue running even after the user logs out. Which command should be used?
62Which directory in the FHS contains essential user command binaries that are needed in single-user mode?
63An administrator needs to permanently mount an ext4 filesystem on /dev/sdb1 to the /data directory. Which file must be edited to ensure the mount persists across reboots?
64Which command is used to query the status of a service managed by systemd?
65An administrator wants to change the priority of a running process with PID 1234 to a lower priority (nicer). The current nice value is 0. Which command will set the nice value to 10?
66A developer creates a hard link to a file and then deletes the original file. What happens to the hard link?
67Which command will display the disk usage of each directory in the current directory, in human-readable format?
68A Linux administrator needs to change the permissions of a file to allow the owner to read and write, the group to read only, and others to have no access. Which chmod command should be used?
69Which command is used to display the contents of a compressed log file without decompressing it?
70A technician wants to find all files owned by user 'jane' in the /home directory. Which command accomplishes this?
71An administrator needs to find all files in /var/log that have been modified within the last 2 days. Which find command should be used?
72A system administrator wants to ensure that a service starts automatically at boot time using systemd. Which command should be used?
73A user reports that a specific process is consuming too much CPU. The administrator needs to change the priority of the process to a lower value (nicer). Which command sequence is appropriate?
74A user wants to create a symbolic link to a file named 'original' in their home directory. Which command creates a symbolic link named 'link'?
75An administrator is troubleshooting a boot issue. The system boots to a console with limited functionality. Which systemd target should be used to bring up the system with network and multi-user support?
76An administrator wants to monitor real-time system resource usage to identify performance bottlenecks. Which two commands are suitable? (Choose two.)
77Which command would a Linux administrator use to locate all files in the /var/log directory that have been modified within the last 7 days?
78A developer wants to change all occurrences of 'foo' to 'bar' in a configuration file and save the changes in-place. Which sed command should be used?
79A system administrator notices that a process with PID 1234 is consuming excessive CPU. The administrator wants to terminate this process gracefully. Which command should be used?
80An administrator wants to start a long-running script in the background so that it continues running even after logging out. Which command should be used?
81An administrator is troubleshooting a service that fails to start. The administrator wants to view the last 50 lines of the service's journal log entries from the current boot. Which journalctl command should be used?
82An administrator needs to apply a set of permissions to an existing directory and all its contents, setting the owner to 'rwx', group to 'rx', and others to '---'. Additionally, newly created files within the directory should inherit the group. Which commands should the administrator run? (Assume the directory is /data, and the group is 'staff'.)
83A technician needs to create a new ext4 filesystem on /dev/sdb1 and mount it persistently at /mnt/data. Which set of commands accomplishes this?
84A system administrator wants to display a list of all currently running processes, including those of other users, with full command lines. Which TWO commands can achieve this? (Select TWO.)
85An administrator needs to update the package cache and upgrade all installed packages on a Debian-based system. Which TWO commands are appropriate for this task? (Select TWO.)
86A Linux administrator needs to view the contents of a compressed log file without decompressing it. Which command should be used?
87An administrator runs the command `ls -l file.txt` and sees the permissions `-rwsr-xr-x`. What special permission is set on this file?
88Which directory in the Filesystem Hierarchy Standard (FHS) contains variable data such as logs and spool files?
89An administrator needs to give a user read and write access to a file without changing the file's group or adding the user to any group. Which method should be used?
90A process is consuming excessive CPU and needs to be stopped immediately. The process ID is 4582. Which command should be used?
91An administrator wants to ensure a service starts automatically at boot on a systemd-based system. Which command should be used?
92A technician needs to check which package provides the file /usr/bin/foo on a CentOS 8 system. Which command should be used?
93Which command creates a symbolic link named 'link.txt' that points to 'original.txt'?
94An administrator wants to gather information about disk usage for a specific directory and its subdirectories. Which TWO commands can be used for this purpose? (Choose two.)
95A 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?
96An administrator wants to find all files larger than 100MB in the /var directory. Which command should be used?
97A system administrator runs the command 'chmod 4755 /usr/local/bin/backup'. What effect does this have on the file?
98Which command displays the current default umask value for a user?
99A system administrator needs to monitor real-time process information and system resource usage. Which two commands can be used for this purpose? (Choose two.)
100A user wants to view the contents of a text file one page at a time. Which two commands can be used? (Choose two.)
101A system administrator is investigating a performance issue and wants to view kernel-related messages. Which three commands can be used to access kernel ring buffer messages? (Choose three.)
102An administrator needs to create a hard link to an existing file. Which two statements are true about hard links? (Choose two.)
103A 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.)
104A Linux administrator needs to create a new user account 'analyst' with a home directory at /home/analyst and the default shell set to /bin/bash. The user should also be added to the existing supplementary group 'research'. Which command will accomplish this in a single step?
105A Linux administrator is troubleshooting a systemd service that fails to start. The service unit file is located at /etc/systemd/system/myservice.service. After editing the unit file, the administrator runs systemctl start myservice, but the service still uses the old configuration. Which command should be run to ensure systemd reloads the modified unit file?
106A Linux administrator needs to scan all currently connected USB devices and display detailed information such as vendor ID, product ID, and device class. Which command should the administrator run?
107A Linux server has a logical volume that is running out of space. The administrator extends the underlying volume group by adding a new physical volume, then extends the logical volume and resizes the filesystem. Which command should be used to resize the ext4 filesystem after extending the logical volume?
108A junior administrator needs to add a persistent mount entry for a new XFS filesystem on /dev/sdb1 at the /data directory so it is mounted automatically at every boot. The administrator opens /etc/fstab and must identify the correct field order for the entry. Which field order should be used in the /etc/fstab line?
109A Linux administrator needs to permanently set the system-wide umask to 027 for all users on a production server. The administrator edits /etc/profile and adds the line 'umask 027'. After rebooting, a user logs in and runs 'umask', which returns 0022. Which of the following is the most likely reason the setting did not take effect?
110A Linux administrator needs to configure a system to automatically mount an NFS share at /mnt/data during boot. The NFS server is 192.168.1.100 exporting /export/data. Which file should the administrator edit to add the appropriate entry?
111A Linux administrator needs to check the available disk space on all mounted filesystems in a human-readable format. Which command should the administrator use?
112A Linux administrator is troubleshooting a system that is running out of disk space on the root filesystem. The administrator needs to identify which directories are consuming the most space. Which TWO commands can be used to find the largest directories? (Choose two.)
113An administrator notices that the /var partition on a production server is nearly full and wants to determine which subdirectories consume the most space before deleting anything. The administrator has root privileges and wants a human-readable summary of each immediate subdirectory under /var, one line per directory. Which command accomplishes this?
114A Linux administrator is troubleshooting a systemd service named 'webapp.service' that fails to start. The administrator runs 'systemctl status webapp.service' and sees that the service is in a failed state. Which TWO commands will provide additional diagnostic information about why the service failed? (Choose two.)
115An administrator manages a server with several systemd services. A service named reportgen.service must not start until another service named dbengine.service is fully active, and reportgen should be stopped automatically if dbengine stops. Which directive combination in the reportgen.service unit file achieves this ordering and dependency?
116A Linux administrator notices that the /home directory is running low on space. They need to identify which user directories are consuming the most disk space. Which command will display the total disk usage of each immediate subdirectory under /home, in human-readable format, sorted by size?
117A Linux administrator is preparing a new server that uses systemd-boot as the boot loader. The administrator wants to verify the current boot loader entries and their order. Which command should the administrator run?
118A junior administrator needs to change the ownership of the file /var/www/html/index.html from user 'www-data' to user 'apache' and group 'apache'. Which command will accomplish this?
119A Linux server is configured to use systemd. The administrator wants to ensure that a custom service named 'app.service' starts automatically at boot, even if it has been manually stopped. Which command should be used?
120A Linux administrator needs to create a new user account named 'jsmith' with a home directory /home/jsmith and the default shell /bin/bash. Which command should the administrator use?
121An administrator needs to monitor a service's log output and wants systemd to capture the output of a specific service unit into the journal, tagged so it can be filtered by the unit name. The administrator also wants to limit how much disk space the journal may consume so it does not fill the root filesystem. Which configuration accomplishes both goals?
122A Linux administrator is troubleshooting a system that fails to mount the root filesystem during boot, dropping to an emergency shell. The administrator suspects that a recently added entry in /etc/fstab is incorrect. Which of the following commands should be used to verify the syntax and mountability of all entries in /etc/fstab without actually mounting them?
123A Linux administrator is troubleshooting a server that fails to mount a filesystem listed in /etc/fstab during boot, causing the system to drop into emergency mode. The administrator wants to prevent the system from entering emergency mode if this particular mount fails, while still attempting to mount it. Which fstab option should be added to the mount entry?
124An administrator needs to schedule a backup script to run every Monday at 2:00 AM. Which crontab entry will accomplish this?
125A Linux administrator needs to view the kernel ring buffer messages to diagnose a hardware issue. Which command should the administrator use?
126A Linux administrator needs to change the runlevel of a systemd-based system to a state where only a single user can log in for maintenance, without starting network services. Which systemd target should the administrator use?
127A Linux administrator needs to create a new user account 'jdoe' with a home directory /home/jdoe and the default shell /bin/bash. Which command will accomplish this?
128A system administrator needs to change the hostname of a Linux server running systemd to 'webserver01'. Which command will accomplish this?
129A Linux administrator is configuring a persistent mount for a new 2TB XFS filesystem on /dev/sdb1 so it mounts automatically at /data with quota accounting enabled. The administrator edits /etc/fstab and adds the entry, then runs mount -a to validate it. Which fstab field combination correctly applies user and group quota accounting on this XFS mount?
130A Linux administrator needs to change the hostname of a system to 'webserver01' permanently. The system uses systemd. Which command should the administrator use?
131A Linux administrator needs to schedule a backup script to run every day at 2:30 AM. Which TWO of the following methods can be used to achieve this? (Choose two.)
Be able to read and set file permissions with umask, find files by size and type, terminate processes with the right signal, and adjust scheduling priority using nice and renice. The single most important thing is knowing which signal or nice value produces the intended effect.
The Courseiva XK0-006 question bank contains 131 questions in the System Management domain, covering the 23% of the exam attributed to this domain in the official CompTIA blueprint. Click any question to see the full explanation and answer breakdown.
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