Linux fluency is expected for backend, DevOps, SRE, and systems roles, and its interviews test command-line proficiency, file permissions, process management, and a bit of shell scripting. Here are the Linux interview questions that actually get asked, with answers. (See also our OS and DevOps guides.)
Commands & files
- Essential commands — grep, find, awk, sed, ps, top, df, du.
- How do you find a file, and search inside files?
- Hard links vs soft (symbolic) links.
- Pipes and redirection (
|,>,>>,2>&1).
Permissions & users
- How do file permissions work — read/write/execute, owner/group/other?
- chmod and the numeric (755, 644) notation.
- chown and sudo.
- What is the root user?
Processes & system
- How do you check and kill a process? Foreground vs background.
- What are signals (SIGKILL vs SIGTERM)?
- Zombie and orphan processes.
- The Linux boot sequence; what is a daemon?
- Basic shell scripting — variables, loops, conditionals.
How to prepare
Linux rounds are scenario-based and verbal. Practise reasoning through permission and process problems out loud. Greenroom runs spoken technical interviews that follow up on your reasoning. Pair it with our OS and DevOps guides.
Frequently asked questions
What are the most common Linux interview questions?
Common Linux questions cover essential commands (grep, find, awk, sed, ps, top, df, du), searching files, hard vs soft links, pipes and redirection, file permissions (read/write/execute, chmod numeric notation, chown, sudo), process management (checking and killing processes, foreground vs background, signals like SIGKILL vs SIGTERM, zombie and orphan processes), the boot sequence, daemons, and basic shell scripting.
How do file permissions work in Linux?
Each file has read (r), write (w) and execute (x) permissions for three categories: owner, group and others. They're shown as rwxr-xr-x and set numerically where r=4, w=2, x=1, so 755 means rwx for owner and r-x for group and others. You change them with chmod and change ownership with chown. Execute permission on a directory means you can enter it.
What is the difference between SIGKILL and SIGTERM?
SIGTERM (signal 15) politely asks a process to terminate, allowing it to clean up resources, save state and shut down gracefully — it can be caught or ignored. SIGKILL (signal 9) forcibly terminates a process immediately and cannot be caught or ignored, so it's used as a last resort when a process won't respond to SIGTERM, at the cost of no cleanup.
How should I prepare for a Linux interview?
Build practical command-line fluency and understand permissions, processes and signals, since Linux rounds are scenario-based ('why can't this process write to this file?'). Practise reasoning through permission and process problems out loud with a voice-based mock interview that follows up, because these rounds reward hands-on comfort explained clearly.