Stage 5: Warm‑Up Legend

Consolidate all basics from Module 1 - Linux architecture, commands, shell, and scripting - through practice and interview‑style drills. Build confidence before moving into deeper modules.

Hackbook Overview

• Review: Kernel, shell, file system, and utilities.
• Commands: Navigation (pwd, ls, cd), file handling (cp, mv, rm), search (grep, find).
• Shell Basics: Environment variables, pipes (|), redirection (>, >>, <).
• Scripting: Shebang (#!/bin/bash), variables, conditionals, loops, arguments.
• Integration: Combine commands and scripts to solve small tasks.

Hands‑On Practice

• Write a script that lists all .log files in /var/log and counts them.
• Use pipes to filter processes containing “ssh” and redirect results to a file.
• Create a script that checks if a directory exists, and if not, creates it.
• Combine grep, wc, and redirection to analyze a text file.

Interview Question Bank

Conceptual

• Q1. What are the key components of Linux architecture?
  A1. Kernel (manages hardware/resources), Shell (command interpreter), File System (organizes data), Utilities (tools like grep).
• Q2. Why is Linux widely used in servers and cloud environments?
  A2. It’s stable, secure, resource‑efficient, and open‑source, making it ideal for scalable infrastructure.

Practical

• Q3. How do you combine commands to list files and count them?
  A3. ls | wc -l → lists files and counts lines.
• Q5. How do you redirect both stdout and stderr to a file?
  A5. command > output.txt 2>&1.

Q4. Write a script that prints “System Ready” if /etc/passwd exists.
A4.bash

#!/bin/bash
if [ -f /etc/passwd ]; then
  echo "System Ready"
fi

Scenario‑Based

• Q6. You’re asked to quickly find the number of running Apache processes.
  A6. ps aux | grep apache | wc -l.
• Q7. A script fails with “Permission denied.” What’s the fix?
  A7. Make it executable: chmod +x script.sh.
• Q8. You need to automate a daily backup. How would you approach it?
  A8. Write a backup script using tar and schedule it with cron.

Behavioral Based

• Q9. How do you prepare for Linux interviews?
  A9. “I practice commands daily, write small scripts, and simulate interview scenarios to build confidence.”
• Q10. Tell me about a time you solved a problem using Linux basics.
  A10. Example: “I used grep and wc to quickly analyze log files, which helped identify a recurring error.”

Cheatsheet (Quick Notes)

• Combine Commands: ls | grep pattern | wc -l.
• Redirection: > overwrite, >> append, 2>&1 redirect errors.
• Script Basics: #!/bin/bash, chmod +x, $1 for arguments.
• Daily Use: ps aux, grep, find, tar, cron.