50 Linux Interview Questions and Answers 2026

Quick Answer: These are the 50 most-asked Linux interview questions and answers for 2026 — commands, files and permissions, processes, networking, and shell scripting. Concise, interview-ready answers for DevOps, SysAdmin, and cloud roles.

Linux Basics

1. What is Linux?
   An open-source, Unix-like operating system kernel that, with GNU tools, powers servers, cloud, and embedded systems.
2. What is the kernel?
   The core of the OS that manages hardware, memory, processes, and system calls.
3. What is the shell?
   A command interpreter (e.g., Bash) that runs commands and scripts.
4. What are common Linux distributions?
   Ubuntu, Debian, RHEL, CentOS Stream, Rocky Linux, Fedora, and Alpine.
5. What is the Filesystem Hierarchy (FHS)?
   The standard directory layout: /etc (config), /var (logs), /home (users), /bin, /usr, etc.
6. What is the difference between absolute and relative paths?
   Absolute starts from root (/); relative is from the current directory.

Files & Directories

7. How do you list files including hidden ones?
   ls -la.
8. How do you find files?
   find (real-time search) or locate (indexed). See our find, locate, grep guide.
9. How do you search text inside files?
   grep "pattern" file.
10. How do you view a large file?
    less, head, or tail -f for live logs.
11. How do you create, copy, move, and delete files?
    touch, cp, mv, rm respectively.
12. How do you compress and extract archives?
    tar -czvf to compress, tar -xzvf to extract.
13. What is the difference between a hard link and a soft link?
    A hard link points to the same inode; a soft (symbolic) link points to a path and can cross filesystems.

Permissions & Users

14. How do Linux file permissions work?
    Read/write/execute (rwx) for owner, group, and others.
15. What does chmod 755 mean?
    Owner rwx (7), group and others r-x (5) — full for owner, read+execute for the rest.
16. What do chmod, chown, and chgrp do?
    chmod changes permissions, chown changes owner, chgrp changes group.
17. What is the difference between su and sudo?
    su switches user (often root); sudo runs a single command with elevated privileges.
18. How do you add a user to a group?
    usermod -aG group user. See our guide.
19. What is the root user?
    The superuser (UID 0) with unrestricted access.
20. What is the setuid bit?
    A permission letting a program run with the file owner’s privileges.

Processes & Performance

21. How do you list running processes?
    ps aux or top/htop.
22. How do you kill a process?
    kill <PID> or kill -9 <PID> to force. See our guide.
23. What is the difference between a process and a thread?
    A process has its own memory; threads share the process’s memory.
24. What is a zombie process?
    A finished process whose parent hasn’t read its exit status, leaving an entry in the process table.
25. What is a daemon?
    A background service process (often ending in ‘d’, like sshd).
26. How do you run a job in the background?
    Append &, or use nohup/systemd for persistence.
27. How do you check disk and memory usage?
    df -h and du -sh for disk; free -h for memory.
28. What is load average?
    The average number of processes waiting to run over 1, 5, and 15 minutes.

Systemd, Boot & Services

29. What is systemd?
    The modern init system and service manager for most Linux distributions.
30. How do you manage a service with systemd?
    systemctl start|stop|status|enable <service>.
31. What happens during the Linux boot process?
    BIOS/UEFI → bootloader (GRUB) → kernel → init/systemd → target/runlevel. See our boot process guide.
32. How do you view system logs?
    journalctl (systemd) or files in /var/log.
33. What is a cron job?
    A scheduled task defined in crontab to run commands at set times.

Networking

34. How do you check network configuration?
    ip addr / ip route (modern) or ifconfig (legacy).
35. How do you test connectivity?
    ping, curl, traceroute, and telnet/nc for ports.
36. How do you see listening ports?
    ss -tulpn (or netstat).
37. How do you copy files between servers?
    scp or rsync. See our SCP guide.
38. What is SSH?
    Secure Shell — an encrypted protocol for remote login and command execution.
39. How do you set a static IP?
    Edit netplan/NetworkManager config. See our static IP guide.

Shell Scripting & Misc

40. What is a shebang?
    The #!/bin/bash line that tells the system which interpreter to use.
41. What are pipes and redirection?
    Pipes (|) pass output between commands; >, >>, < redirect to/from files.
42. What is the difference between > and >>?
    > overwrites; >> appends.
43. What are environment variables?
    Key-value settings available to processes; view with printenv, set with export. See our guide.
44. What are $?, $0, and $1 in scripts?
    $? is the last exit code, $0 the script name, $1 the first argument.
45. What does exit code 0 mean?
    Success; non-zero indicates an error.
46. How do you make a script executable?
    chmod +x script.sh then run ./script.sh.
47. What is the difference between soft and hard reboot?
    Soft uses the OS (reboot); hard cuts power abruptly.
48. How do you check OS and kernel version?
    uname -r for kernel, cat /etc/os-release for distro.
49. What is the difference between apt and dpkg?
    dpkg installs local .deb files; apt resolves dependencies from repositories. See our .deb install guide.
50. How do you schedule a one-time future task?
    Use the at command (vs cron for recurring).

Frequently Asked Questions

Are these Linux questions good for DevOps interviews?

Yes — Linux fundamentals, permissions, processes, and shell scripting are core to almost every DevOps and SRE interview.

Which Linux topics are asked most often?

File permissions, process management, networking commands, systemd services, the boot process, and shell scripting basics.

How can I practice Linux commands?

Use a Linux VM or WSL, work entirely from the terminal, and follow our hands-on Linux guides.

Related: Linux for DevOps Engineers · Essential Linux Commands · DevOps Interview Questions