shell-scripting

Shell Scripting Standards

When to Use

• Writing new shell scripts
• Refactoring existing scripts
• Adding new functions

Script Structure

1. File Header

#!/bin/bash

# Script description
# https://github.com/mylee04/code-notify

set -e  # Exit on error

2. Constants (UPPER_CASE)

VERSION="1.2.0"
CONFIG_DIR="$HOME/.claude"
DEFAULT_SOUND="Glass"

3. Functions (snake_case)

# Description of function
# Arguments: $1 = name, $2 = optional value
function_name() {
    local name="$1"
    local value="${2:-default}"

    # Function body
}

4. Main Logic

# Main execution
main() {
    validate_args "$@"
    do_work
    cleanup
}

main "$@"

Best Practices

Variable Handling

# Good - quoted variables
echo "$message"
path="$HOME/.config"

# Bad - unquoted
echo $message
path=$HOME/.config

Conditionals

# Good - double brackets
if [[ -n "$var" ]]; then
    echo "not empty"
fi

# Bad - single brackets
if [ -n "$var" ]; then
    echo "not empty"
fi

Command Existence Check

# Good
if command -v terminal-notifier &> /dev/null; then
    terminal-notifier -message "Hello"
fi

# Bad
if which terminal-notifier; then
    terminal-notifier -message "Hello"
fi

Error Handling

# Good - explicit error handling
if ! some_command; then
    echo "Error: command failed" >&2
    exit 1
fi

# Good - trap for cleanup
cleanup() {
    rm -f "$temp_file"
}
trap cleanup EXIT

Local Variables in Functions

# Good
my_function() {
    local input="$1"
    local result
    result=$(process "$input")
    echo "$result"
}

# Bad - pollutes global scope
my_function() {
    input="$1"
    result=$(process "$input")
    echo "$result"
}

Common Patterns

OS Detection

detect_os() {
    case "$(uname -s)" in
        Darwin*)    echo "macos" ;;
        Linux*)     echo "linux" ;;
        CYGWIN*|MINGW*|MSYS*) echo "windows" ;;
        *)          echo "unknown" ;;
    esac
}