Linux Host and Filesystem Fundamentals

Clarifying Questions to Ask

• Which Linux distribution and shell should be assumed?
• Are privileged commands allowed, or should the answer work as an ordinary user?
• Is the system local, containerized, or running under an orchestration platform?

Part 1: Inspect Memory and Explain Swap

How would you inspect memory usage on a Linux host? Explain what swap is, why it exists, and why low “free” memory or nonzero swap use is not automatically evidence of a problem.

Candidate hint: Separate process memory, reclaimable cache, memory pressure, and historical swap placement.

What This Part Should Cover

• Useful commands and fields rather than one unexplained number
• Available memory, cache, swap, and pressure interpretation
• Limits of a single snapshot

Part 2: Working Directory and Listing Without ls

Which command prints the current working directory? Give at least two safe ways to enumerate entries in the current directory without using ls, including hidden entries where practical.

Candidate hint: Be explicit about recursion, dotfiles, quoting, and unusual filenames.

What This Part Should Cover

• pwd semantics
• Shell expansion or find-based alternatives and their caveats
• Filename-safe output when results feed another command

Part 3: Threads and Processes

Compare a Linux process with a thread. Discuss address spaces, resources, scheduling, communication, isolation, and failure implications.

Candidate hint: Avoid saying that threads are not scheduled entities; focus on what is shared and what is private.

What This Part Should Cover

• Shared versus isolated state
• Context, communication, synchronization, and fault boundaries
• Practical performance trade-offs without absolute claims

Part 4: Symbolic and Hard Links

Explain the difference between a symbolic link and a hard link. Cover inode relationships, filesystem boundaries, directories, deletion of the target name, and how common tools display them.

Candidate hint: Ask what directory entry each link points to and what keeps file data alive.

What This Part Should Cover

• Path indirection versus another name for one inode
• Lifetime and broken-link behavior
• Cross-filesystem and directory restrictions

Part 5: Delete a File Named -rf

A regular file in the current directory is literally named -rf. How can you delete that exact file without it being interpreted as command options? Explain why the command is safe.

Candidate hint: Either terminate option parsing or make the operand stop beginning with a hyphen.

What This Part Should Cover

• A correctly quoted, exact operand
• -- or an explicit relative path
• Awareness that quoting alone does not change a leading hyphen into a non-option

Part 6: Recover After an Accidental Recursive Delete

Suppose a recursive removal deleted the current directory's contents. Is there a general shell command that restores those files? Explain what deletion changes and give a responsible immediate response and recovery order.

Candidate hint: Distinguish unlinking names from securely erasing blocks, but do not promise that unallocated data is recoverable.

What This Part Should Cover

• No universal undo and why continued writes reduce recovery chances
• Backups, snapshots, version control, and still-open file descriptors
• Filesystem-specific recovery as a last resort, not a guarantee