DevOps Job Interviews: Why You Can’t Fake Linux
When you start preparing for DevOps interviews, you quickly realize something: you can’t “fake” Linux.
Interviewers don’t want textbook answers. They want to know if you can actually unpack an operating or broken system in the terminal and extract the technical details that you need to adjust. If you’ve been there, if you’ve solved real problems using Linux, you know what I mean here.
In other words, employers want real problem-solving skills. The reason for this approach is that very often companies’ infrastructure depends on the admin’s crucial troubleshooting abilities. It is not something you can learn from the book.
That’s why I made the video Everything You Need to Know for a Linux DevOps Interview. It’s also why I believe that mastering Linux is the best step any aspiring DevOps engineer can take.
In this post, I’ll walk through the core Linux areas you’re likely to face in a DevOps interview, and how they connect with three key exams from LPI:
- Linux Essentials (exam objectives)
- LPIC-1 (exam 101 and 102 objectives)
- DevOps Tools Engineer (exam objectives)
Why is Linux Essential in DevOps?
So, start asking yourself: How do I contextualize Linux in the DevOps ecosystem? Because it’s not about knowing a few commands. It’s about understanding how Linux interconnects other complex systems. A few examples follow of the DevOps enablers that cannot work without Linux:
- Configuration management: Configuration tools like Ansible, Chef, and Puppet rely heavily on Linux for automation, upgrades, and infrastructure administration.
- CI/CD: Pipelines in systems such as GitLab or Jenkins use Linux both to host applications and to build and deliver software.
- Container technologies: Docker and Podman are both based on Linux kernel features such as namespaces and cgroups to establish isolation between the container and the host operating system.
- Monitoring: Tools such as Grafana, Prometheus, and ELK monitor and analyze statistics from applications hosted on Linux servers.
What You’re Expected to Know
A DevOps interviewer won’t ask you to recite commands. They’ll ask whether you’ve used them when it mattered. The same logic applies to the Linux Essentials certificate and DevOps Tools Engineer certification.
You’re expected to be confident with the terminal and the functioning of Linux systems. For a start, understand how the Linux filesystem works, how to manipulate files, what the different types are, etc.Then, of course it’s important to be comfortable with related operations such as navigating directories, understanding permissions, and changing ownership.
On top of the basic file operations, you should be able to explain how to transfer files to remote servers with programs like scp and rsync. You should be able to check how much space is left on a disk, how long a server has been running, and which services are eating up memory. That means using tools like df, uptime, and top, and understanding their output.
You should also be able to search and manage files, especially in production. That includes using find, grep and awk to locate files based on size, owner, or permissions. It is also useful to know how to debug a service using utilities such as tail -f to follow live logs.
Processes are at the core of system stability. Can you check what’s running on your server (ps, top, htop)? Can you identify which processes consume the highest amount of CPU or RAM? Can you terminate a process that’s stuck (kill) or change the process priority (nice, renice)? Can you move tasks to the background and bring them back (&, fg, bg)? If the answer is yes, you’re ready to talk about key DevOps tasks such as monitoring and resource utilization.
Then there’s one of the most crucial parts of your daily work: networking. This involves much more than one tool. It is more of a complex ecosystem of connections, equipped with multiple tools and utilities.
Let’s start with the basics. You need to understand interfaces (ip a), connections (ss, netstat), reachability (ping, traceroute), and network services like DNS (dig, host, nslookup). If a service isn’t responding, can you track why, or where the packet fails? Imagine that there is no connectivity to the production server. What do you do? Which command would you use? This topic is explained well in LPI’s Learning Materials for LPIC-1 102.
Very often you will be asked to troubleshoot SSH connections…and speaking about SSH…
Here we get to the enormous topic of security. SSH is a given. You should know how to connect to the remote server using private-public key infrastructure, use different ports, generate and copy keys, and manage all the key SSH-related files. It is really crucial for you to be able to explain how public/private key authentication works, as this is one of the most common and crucial tasks in your daily DevOps job. These aren’t tricks. They’re basics. They show whether Linux is something you actually know, or just studied for the interview.
The Recipe for Success? Learning It the Right Way
I didn’t learn this by reading a book. I learned it by coding real-life projects and spending many hours in front of the command line. And there is still a lot of room for improvement in my Linux skills. You will have to do the same, so to support your journey, I recommend these free Learning Materials from LPI:
These resources are practical, tested, and based on the same logic that got me through interviews and certification prep. Exciting update: Learning Materials for the DevOps Tools Engineer 2.0 Certification are now available!
And, yes: you can learn Jenkins, Docker, or Ansible. But if you don’t understand the shell beneath them, you’ll always be guessing what to do in a real-life environment. Familiarity with Linux gives you this extra, deeper layer of understanding, which is crucial for instance in troubleshooting.
I still remember how often I failed when I started my DevOps journey and tried to jump directly to Kubernetes. It’s a no-go without solid Linux skills. Because Linux isn’t just a tool in DevOps: it’s the ground beneath your feet and the basis for every other tool.
