Overview

This series teaches sed through heavily annotated, self-contained shell examples. Each example focuses on a single concept and includes inline annotations explaining what each command does, why it matters, and what output or transformation results from it. All examples use echo piped to sed or heredoc input so you can run them directly in any Unix-like shell without creating files first.

Series Structure

The examples are organized into three levels based on complexity:

• Beginner — Basic substitution, print and delete commands, line addressing, range addressing, in-place editing, and single-character commands
• Intermediate — Capture groups, extended regex, hold space, multiline processing, branching and labels, and sed script files
• Advanced — GNU vs BSD portability, complex multiline transforms, config file manipulation, log processing, pipeline integration, and real-world automation scripts

Structure of Each Example

Every example follows a consistent five-part format:

1. Brief Explanation — what the sed command does and why it matters (2-3 sentences)
2. Mermaid Diagram — visual representation of data flow or command execution (when appropriate)
3. Heavily Annotated Code — shell commands with # => comments describing each flag, address, command, and its effect on the pattern space
4. Key Takeaway — the core insight to retain from the example (1-2 sentences)
5. Why It Matters — production relevance and real-world impact (50-100 words)

How to Use This Series

Each page presents annotated shell one-liners and short scripts. Read the annotations alongside the command to understand both the mechanics and the intent. The examples build on each other within each level, so reading sequentially gives the fullest understanding. Every example is self-contained — you can copy any single example and run it immediately without setup.