Bash Script Generator

Generate production-ready, portable, and safe Bash scripts.

When to Use

•Creating automation scripts
•Writing deployment scripts
•Building CI/CD helper scripts
•System administration tasks

Core Rules

1. Use Strict Mode

Always start with set -euo pipefail.

2. Quote All Variables

Use "$variable" to prevent word splitting.

3. Use Functions

Organize code into functions with local variables.

4. Add Error Handling

Use trap for cleanup and meaningful error messages.

5. Validate Inputs

Check required arguments and file existence before use.

Script Template

bash

#!/usr/bin/env bash
#
# Script: script-name.sh
# Description: Brief description of what the script does
# Usage: ./script-name.sh [options] <arguments>
#
# Options:
#   -h, --help     Show this help message
#   -v, --verbose  Enable verbose output
#   -d, --dry-run  Show what would be done without executing
#

set -euo pipefail
IFS=$'\n\t'

# =============================================================================
# Configuration
# =============================================================================

readonly SCRIPT_NAME="$(basename "$0")"
readonly SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"

# Default values
VERBOSE=false
DRY_RUN=false

# =============================================================================
# Logging Functions
# =============================================================================

log_info() {
    echo "[INFO] $*" >&2
}

log_warn() {
    echo "[WARN] $*" >&2
}

log_error() {
    echo "[ERROR] $*" >&2
}

log_debug() {
    if [[ "$VERBOSE" == true ]]; then
        echo "[DEBUG] $*" >&2
    fi
}

# =============================================================================
# Helper Functions
# =============================================================================

usage() {
    cat << EOF
Usage: $SCRIPT_NAME [options] <arguments>

Description:
    Brief description of what the script does.

Options:
    -h, --help      Show this help message
    -v, --verbose   Enable verbose output
    -d, --dry-run   Show what would be done without executing

Examples:
    $SCRIPT_NAME --verbose input.txt
    $SCRIPT_NAME --dry-run --verbose input.txt

EOF
    exit 0
}

die() {
    log_error "$*"
    exit 1
}

require_command() {
    local cmd="$1"
    if ! command -v "$cmd" &> /dev/null; then
        die "Required command not found: $cmd"
    fi
}

confirm() {
    local message="${1:-Are you sure?}"
    read -r -p "$message [y/N] " response
    case "$response" in
        [yY][eE][sS]|[yY]) return 0 ;;
        *) return 1 ;;
    esac
}

# =============================================================================
# Main Functions
# =============================================================================

parse_args() {
    while [[ $# -gt 0 ]]; do
        case "$1" in
            -h|--help)
                usage
                ;;
            -v|--verbose)
                VERBOSE=true
                shift
                ;;
            -d|--dry-run)
                DRY_RUN=true
                shift
                ;;
            --)
                shift
                break
                ;;
            -*)
                die "Unknown option: $1"
                ;;
            *)
                break
                ;;
        esac
    done

    # Store remaining arguments
    ARGS=("$@")
}

validate_args() {
    # Add validation logic here
    if [[ ${#ARGS[@]} -lt 1 ]]; then
        die "Missing required argument. Use --help for usage."
    fi
}

main() {
    parse_args "$@"
    validate_args

    log_info "Starting $SCRIPT_NAME"
    log_debug "Verbose mode enabled"

    if [[ "$DRY_RUN" == true ]]; then
        log_warn "Dry-run mode - no changes will be made"
    fi

    # Main script logic here
    for arg in "${ARGS[@]}"; do
        log_info "Processing: $arg"

        if [[ "$DRY_RUN" == false ]]; then
            # Actual execution
            :
        fi
    done

    log_info "Completed successfully"
}

# =============================================================================
# Entry Point
# =============================================================================

main "$@"

Best Practices

Safety Options

bash

# Always use at the start of scripts
set -euo pipefail

# -e: Exit on error
# -u: Error on undefined variables
# -o pipefail: Exit on pipe failures

Variable Handling

bash

# Always quote variables
echo "$variable"

# Use default values
name="${1:-default_name}"

# Use readonly for constants
readonly CONFIG_FILE="/etc/app/config.yaml"

# Use local in functions
my_function() {
    local result=""
    result=$(some_command)
    echo "$result"
}

Error Handling

bash

# Trap for cleanup
cleanup() {
    rm -f "$TEMP_FILE"
}
trap cleanup EXIT

# Check command existence
command -v kubectl &> /dev/null || die "kubectl not found"

# Check file existence
[[ -f "$config_file" ]] || die "Config file not found: $config_file"

Input Validation

bash

# Validate required arguments
[[ -n "${1:-}" ]] || die "First argument is required"

# Validate file exists
[[ -f "$input_file" ]] || die "File not found: $input_file"

# Validate directory exists
[[ -d "$output_dir" ]] || mkdir -p "$output_dir"

# Validate numeric input
[[ "$count" =~ ^[0-9]+$ ]] || die "Count must be a number"

Common Patterns

Process Files

bash

while IFS= read -r line || [[ -n "$line" ]]; do
    process_line "$line"
done < "$input_file"

Array Operations

bash

# Declare array
declare -a items=("a" "b" "c")

# Iterate
for item in "${items[@]}"; do
    echo "$item"
done

# Length
echo "Count: ${#items[@]}"

Temporary Files

bash

TEMP_FILE=$(mktemp)
trap 'rm -f "$TEMP_FILE"' EXIT

echo "data" > "$TEMP_FILE"

JSON with jq

bash

# Parse JSON
name=$(echo "$json" | jq -r '.name')

# Iterate JSON array
echo "$json" | jq -c '.items[]' | while read -r item; do
    echo "$item" | jq -r '.id'
done

Kubernetes Helpers

bash

# Get pod names
kubectl get pods -n "$namespace" -o jsonpath='{.items[*].metadata.name}'

# Wait for rollout
kubectl rollout status deployment/"$deployment" -n "$namespace" --timeout=300s

# Port forward with background cleanup
kubectl port-forward svc/"$service" 8080:80 &
PF_PID=$!
trap 'kill $PF_PID 2>/dev/null' EXIT

DevOps Script Examples

Deploy Script

bash

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

deploy() {
    local env="$1"
    local version="$2"

    log_info "Deploying version $version to $env"

    helm upgrade --install app ./charts/app \
        -n "$env" \
        --set image.tag="$version" \
        --wait \
        --timeout 5m
}

Health Check Script

bash

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

check_health() {
    local endpoint="$1"
    local max_retries=30
    local retry_interval=10

    for ((i=1; i<=max_retries; i++)); do
        if curl -sf "$endpoint/health" > /dev/null; then
            log_info "Health check passed"
            return 0
        fi
        log_warn "Attempt $i/$max_retries failed, retrying in ${retry_interval}s..."
        sleep "$retry_interval"
    done

    die "Health check failed after $max_retries attempts"
}

Validation

bash

# Syntax check
bash -n script.sh

# ShellCheck
shellcheck script.sh

# Test execution
bash -x script.sh  # Debug mode