Linux and Command Line

Foundational skill (2015-2025). See the master guide for context.

Why QA Engineers Need Command Line Skills

Test environments run on Linux. CI/CD pipelines run on Linux. Docker containers run on Linux. Application servers, databases, and log aggregators run on Linux. A QA engineer who cannot navigate a terminal is limited to whatever the GUI tools expose. Command line skills let you investigate issues directly, automate repetitive tasks, and work effectively in environments where there is no graphical interface.

Topics Covered

1. Linux Basics — 01-linux-basics/

• Directory Structure — understanding the Linux filesystem and where QA engineers spend their time
• Permissions and Processes — file permissions, process management, and port troubleshooting

2. Essential Commands — 02-essential-commands/

• grep, curl, and jq — searching logs, making HTTP requests, and parsing JSON
• Pipes and Redirection — chaining commands, redirecting output, and building powerful one-liners

3. Scripting and Containers — 03-scripting-and-containers/

• Bash Scripting — writing practical automation scripts for QA tasks
• Docker Basics — running containers, Compose for test environments
• Logs and Environment — reading logs, managing environment variables, quick reference, and interview talking points

How to Use This Chapter

Start with the Linux basics to build a foundation. Move into essential commands that you will use daily. Finish with scripting and containers for automation and environment management.

The best way to learn command line skills is to use them. Open a terminal and try every command in this chapter.