Linux Cheat Sheet 2026

The 30 highest-yield Linux facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. Which nftables command lists all current rules and tables? → nft list ruleset
2. What is a Docker bind mount, as opposed to a named volume? → A direct mapping of a specific host directory or file path into the container
3. Which command converts an existing linear logical volume to use RAID1 mirroring? → lvconvert --type raid1 -m1 /dev/vg0/lv1
4. Which directory contains essential system files such as the kernel and bootloader files? → /boot
5. Which of the following commands is used to determine a system's current IP address? → Ifconfig
6. How should Linux professionals handle technical procedures that have been updated or revised? → Review the updates, complete any required training, and implement the revised procedures
7. Which file defines the default password aging policy for new user accounts on a Linux system? → /etc/login.defs
8. Which command would you use to display a detailed, multi-line report of the attributes for a specific Physical Volume, such as `/dev/sda2`? → `pvdisplay /dev/sda2`
9. Which docker run flag makes a container automatically restart unless it is explicitly stopped by the administrator? → --restart=unless-stopped
10. A Linux machine does not have Internet connectivity. Which command displays information about the system's network gateway? → Route
11. An admin wants to capture all failed SSH login attempts from the journal. Which journalctl command filters only for sshd unit logs? → journalctl -u sshd
12. What is the most effective approach to system administration in the Linux field? → Systematic planning and continuous improvement
13. Which command checks whether auditd is actively capturing events and shows its current running status? → auditctl -s
14. What is the primary consideration when implementing changes to networking? → Impact assessment and change management
15. Which file contains the mapping between major device numbers and kernel modules/drivers on a Linux system? → /proc/devices
16. How do you rate-limit SSH connections using iptables to prevent brute-force attacks? → iptables -A INPUT -p tcp --dport 22 -m recent --rcheck --seconds 60 --hitcount 4 -j DROP
17. What is the most effective approach to package management in the Linux field? → Systematic planning and continuous improvement
18. Which lvcreate option specifies the number of stripes when creating a striped logical volume? → -i
19. How should Linux professionals handle technical procedures that have been updated or revised? → Review the updates, complete any required training, and implement the revised procedures
20. Which command saves a Docker image to a tar archive file for offline transfer? → docker save myimage -o myimage.tar
21. Which command would a sysadmin use to find which RPM package owns the file /usr/bin/ssh? → rpm -qf /usr/bin/ssh
22. What is the MOST effective way for new Linux professionals to build competency in their field? → Combining formal education, mentored practice, and ongoing professional development
23. Which of the following is a digital data transfer interface that combines audio and video? → HDMI
24. Which nftables table type handles both IPv4 and IPv6 traffic in a single ruleset? → inet
25. What is the effect of placing `2>&1` at the end of a command? → Sends stderr to the same destination as stdout
26. Which AppArmor command loads a profile in enforce mode? → aa-enforce
27. What is the effect of setting the 'skip_activation' flag on a logical volume? → The LV will not be activated automatically during system boot
28. Which personal protective equipment (PPE) principle applies to ALL Linux certified professionals regardless of their specific role? → PPE must be properly fitted, maintained, and replaced as needed
29. Which command sends ICMP echo requests to a host to test basic network reachability? → ping
30. What is the PRIMARY purpose of obtaining Linux certification in Linux? → To demonstrate verified competency and adherence to professional standards