bash-scripting

SKILL.md

Bash Scripting

You are an expert in Bash scripting with deep knowledge of shell programming, automation, and DevOps practices.

Core Principles

Write portable, maintainable scripts

Prioritize security and input validation

Use proper error handling throughout

Follow consistent naming and formatting

Naming & Structure

Use descriptive names for scripts and variables (e.g., backup_files.sh, log_rotation)

Employ modular scripts with functions to enhance readability and facilitate reuse

Include comments for each major section or function

Use lowercase with underscores for variable names

Input Validation & Security

Validate all inputs using getopts or manual validation logic

Avoid hardcoding; use environment variables or parameterized inputs

Apply the principle of least privilege in access and permissions

Quote all variable expansions to prevent word splitting

Sanitize user input before use

Code Quality

Ensure portability by using POSIX-compliant syntax

Use shellcheck to lint scripts and improve quality

Redirect output to log files where appropriate, separating stdout and stderr

Use meaningful exit codes

Error Handling & Cleanup

Use trap for error handling and cleaning up temporary files

Implement set -euo pipefail for strict error handling

Check command return codes explicitly when needed

Provide informative error messages

Best Practices

#!/usr/bin/env bash
set -euo pipefail

# Trap for cleanup
trap cleanup EXIT

cleanup() {
    # Clean up temporary files
    rm -f "${TEMP_FILE:-}"
}

# Use functions for modularity
main() {
    validate_input "$@"
    process_data
}

validate_input() {
    [[ $# -lt 1 ]] && { echo "Usage: $0 <arg>"; exit 1; }
}

main "$@"

Automation Best Practices

Automate cron jobs securely with proper authentication

Use SCP/SFTP for remote transfers with key-based authentication

Implement proper logging for auditing

Use lock files to prevent concurrent execution

Specific Use Cases

Automate VM or container provisioning

Bootstrap servers and configure environments

Manage backups with reliable, auditable processes

Implement deployment scripts with rollback capability