Linux Basic — Clean & Readable Code Practice

Practice Exercises — Clean & Readable Code

Refactor existing scripts to make them maintainable.

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Warm-up

1. Take a script with single-letter variable names and rename them to descriptive snake_case names.
2. Add a header block with description, usage, dependencies, and exit codes.
3. Extract a repeated 10-line block into a function.

Naming

1. Convert all environment variables to UPPER_CASE.
2. Convert all local variables to lowercase_snake_case.
3. Rename functions to verb-first: userCount() → get_user_count().

Commenting

1. Find 3 “what” comments and rewrite them as “why” comments.
2. Add a comment explaining a magic number (e.g., sleep 5).
3. Remove redundant comments that just restate the code.

Organization

1. Refactor a monolithic 200-line script into 5–7 functions, each with a single responsibility.
2. Move all readonly constants to the top.
3. Add a main() function and move script body into it.

ShellCheck

1. Run shellcheck on a script and fix all quoting warnings (SC2086, SC2046).
2. Fix cd usage (SC2164) by adding || exit.
3. Fix array expansion (SC2128) by using "${arr[@]}".
4. Achieve zero warnings at default level.

Full Refactor

1. Take a legacy script with no header, cryptic names, and no functions. Apply all techniques from this chapter to make it production-ready.

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Verification Checklist

• All variables quoted unless splitting is intentional
• ShellCheck passes with zero warnings
• Functions are < 50 lines each
• Script has a complete header
• main() is at the bottom
• Constants are readonly and at the top

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Next chapter → Optimizing Scripts