Test: Module 02 — Linux and Shell¶

Total Points: 37 pts (Easy: 5 + Medium: 10 + Hard: 12 + Expert: 10) Bonus Available: 5 pts

Section 1: Easy Questions (1 pt each)¶

Q1. What is the purpose of the /etc directory?

Q2. What does set -euo pipefail do in a bash script?

Q3. What command shows all running processes with detailed information?

Q4. What octal value represents rwxr-xr-x permissions?

Q5. What systemd command shows the logs for a service named nginx?

Section 2: Medium Questions (2 pts each)¶

Q6. Explain the difference between SIGTERM and SIGKILL. When would you use each?

Q7. What is the difference between a hard link and a symbolic link? When would you use each?

Q8. Write a cron expression that runs a script every weekday at 6:30 AM.

Q9. Explain what the trap command does in bash and give an example use case.

Q10. What is stdin, stdout, and stderr? How would you redirect stderr to a log file while letting stdout go to the terminal?

Section 3: Hard Questions (3 pts each)¶

Q11. Find and fix the bugs in this bash script:

#!/bin/bash
FILES = $(ls /tmp/*.log)
for file in $FILES; do
    if [ -f $file ]; then
        mv $file /archive/$file
    fi
done

Q12. Write a systemd service unit file for an application that: runs as a non-root user, restarts on failure, limits memory to 512MB, and protects the system filesystem from writes.

Q13. Write a bash one-liner that extracts all unique IP addresses from an nginx access log file and counts how many times each appears, sorted by frequency.

Q14. A script runs fine interactively but fails when run from cron. What are the most common causes of this and how do you debug it?

Section 4: Expert Questions (5 pts each)¶

Q15. Design a bash deployment script architecture for a zero-downtime rolling update of a fleet of application servers. Describe the functions you would write, the error handling strategy, and how you would handle partial failures.

Q16. Explain Linux process namespaces and cgroups. How do these kernel features enable Docker containers? What is the difference between a container and a virtual machine at the kernel level?

Bonus¶

Bonus 1. (+5 pts) Explain what happens step-by-step when you run ls /tmp in a bash shell — from keypress to output. Include: shell parsing, PATH lookup, fork/exec, file descriptor inheritance, and the return of output to the terminal.