Shell Best Practices

What it does

This skill helps AI agents generate shell scripts that adhere to secure coding best practices. It provides guidance on script foundation, strict error handling, variable management, and error messaging, ensuring scripts are robust, maintainable, and minimize potential vulnerabilities. The skill promotes efficient scripting by incorporating recommendations for shebang selection, quoting variables, using meaningful names, and implementing proper exit codes.

When to use it

• When generating shell scripts that require a high level of security and reliability.
• To ensure newly created scripts follow consistent coding standards and best practices.
• For automating tasks where errors could have significant consequences.
• When needing assistance with structuring the initial framework for a new shell script, including headers and variable declarations.

Key capabilities

• Shebang Selection: Guidance on choosing appropriate shebang lines (e.g., /usr/bin/env bash, /bin/bash, /bin/sh).
• Strict Error Handling: Promotes the use of set -euo pipefail for robust error checking.
• Variable Quoting: Emphasizes the importance of quoting variables to prevent word splitting and glob expansion.
• Meaningful Variable Names: Encourages using descriptive variable names instead of single-letter abbreviations.
• Default Values: Provides methods for assigning default values to variables if they are unset or empty.
• Readonly and Local Variables: Guidance on declaring constants with readonly and function-local variables with local.
• Exit Codes: Recommends using meaningful exit codes (e.g., EXIT_SUCCESS, EXIT_FAILURE).
• Cleanup Traps: Suggests implementing cleanup traps to handle temporary files and restore state.

Example prompts

• "Generate a shell script that lists all .txt files in the current directory, ensuring proper error handling."
• "Create a bash script with a header template including description and usage instructions."
• "Write a shell script to copy a file, using best practices for variable quoting."

Tips & gotchas

• The skill focuses on shell scripting best practices, not general programming concepts.
• Pay attention to the recommendations regarding set -euo pipefail as they are crucial for error handling.
• The script header template is a suggestion, and can be customized based on project needs.