bash

dralgorhythm's avatarfrom dralgorhythm

Write Bash scripts following best practices. Use when creating shell scripts, automation, or CLI tools. Covers safe scripting patterns.

⭐1stars🔀0forks📁View on GitHub🕐Updated Dec 20, 2025
[Developer Tools]

When & Why to Use This Skill

This Claude skill provides a comprehensive framework for generating robust, production-ready Bash scripts. It focuses on industry best practices, including safe scripting patterns like 'set -euo pipefail', proper error handling, and modular function design. By automating the creation of shell scripts and CLI tools, it ensures code reliability, security, and maintainability for developers and system administrators.

Use Cases

  • System Automation: Creating reliable scripts for routine tasks such as automated backups, log rotation, and environment setup.
  • CLI Tool Development: Building custom command-line interfaces with structured argument parsing, logging, and user feedback.
  • CI/CD Pipeline Scripting: Writing safe and predictable shell scripts for deployment processes that require strict error catching and cleanup traps.
  • Legacy Script Refactoring: Modernizing older shell scripts by applying best practices like local variable scoping, 'readonly' constants, and ShellCheck-compliant syntax.
namebash
descriptionWrite Bash scripts following best practices. Use when creating shell scripts, automation, or CLI tools. Covers safe scripting patterns.
allowed-toolsRead, Write, Edit, Bash, Glob, Grep

Bash Scripting

Script Template

#!/usr/bin/env bash
set -euo pipefail
IFS=$'\n\t'

# Script description
# Usage: ./script.sh <arg1> <arg2>

readonly SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"

main() {
    local arg1="${1:-default}"

    # Script logic here
    echo "Running with: $arg1"
}

main "$@"

Safety Settings

set -e          # Exit on error
set -u          # Error on undefined variables
set -o pipefail # Catch pipe failures
set -x          # Debug: print commands

Variables

# Declaration
readonly CONST="immutable"
local var="function scoped"

# Default values
name="${1:-default}"      # Use default if unset
name="${1:?Error: missing}"  # Error if unset

# String operations
"${var^^}"    # Uppercase
"${var,,}"    # Lowercase
"${var#prefix}"  # Remove prefix
"${var%suffix}"  # Remove suffix

Conditionals

# File tests
[[ -f "$file" ]]  # Is file
[[ -d "$dir" ]]   # Is directory
[[ -r "$file" ]]  # Is readable
[[ -x "$file" ]]  # Is executable

# String tests
[[ -z "$var" ]]   # Is empty
[[ -n "$var" ]]   # Is not empty
[[ "$a" == "$b" ]] # Equals

# Numeric tests
(( num > 5 ))     # Greater than
(( num == 5 ))    # Equals

Functions

log() {
    local level="$1"
    local message="$2"
    echo "[$(date +'%Y-%m-%d %H:%M:%S')] [$level] $message" >&2
}

die() {
    log "ERROR" "$1"
    exit 1
}

require_command() {
    command -v "$1" >/dev/null 2>&1 || die "Required command not found: $1"
}

Error Handling

# Trap for cleanup
cleanup() {
    rm -rf "$TMP_DIR"
}
trap cleanup EXIT

# Catch errors
if ! result=$(some_command 2>&1); then
    die "Command failed: $result"
fi

Loops

# For loop
for item in "${array[@]}"; do
    echo "$item"
done

# While read
while IFS= read -r line; do
    echo "$line"
done < file.txt

# Process substitution
while read -r line; do
    echo "$line"
done < <(command)

Best Practices

  1. Quote all variables: "$var"
  2. Use [[ instead of [
  3. Use local in functions
  4. Use readonly for constants
  5. Always use set -euo pipefail
  6. Use shellcheck for linting