Initial commit

skills/shell-scripting/references/template.sh

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+#!/usr/bin/env bash
+
+# Script: template.sh
+# Description: Production-ready Bash script template with best practices
+# Usage: template.sh [OPTIONS] <command>
+
+# Exit on error, undefined variables, and pipe failures
+set -euo pipefail
+
+# Safer word splitting (newline and tab only)
+IFS=$'\n\t'
+
+# Constants
+readonly SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+readonly SCRIPT_NAME="$(basename "${BASH_SOURCE[0]}")"
+readonly VERSION="1.0.0"
+
+# Colors for output
+readonly RED='\033[0;31m'
+readonly GREEN='\033[0;32m'
+readonly YELLOW='\033[1;33m'
+readonly BLUE='\033[0;34m'
+readonly NC='\033[0m' # No Color
+
+# Global variables
+VERBOSE=false
+DRY_RUN=false
+LOG_FILE=""
+
+# Logging functions
+log_info() {
+    echo -e "${BLUE}[INFO]${NC} $*"
+}
+
+log_success() {
+    echo -e "${GREEN}[SUCCESS]${NC} $*"
+}
+
+log_warning() {
+    echo -e "${YELLOW}[WARNING]${NC} $*" >&2
+}
+
+log_error() {
+    echo -e "${RED}[ERROR]${NC} $*" >&2
+}
+
+log_debug() {
+    if [[ "$VERBOSE" == true ]]; then
+        echo -e "${BLUE}[DEBUG]${NC} $*" >&2
+    fi
+}
+
+# Usage information
+usage() {
+    cat <<EOF
+Usage: $SCRIPT_NAME [OPTIONS] <command> [args...]
+
+Description of what this script does.
+
+OPTIONS:
+    -h, --help              Show this help message and exit
+    -v, --verbose           Enable verbose output
+    -d, --dry-run           Show what would be done without doing it
+    -l, --log FILE          Write log output to FILE
+    -V, --version           Show version information
+
+COMMANDS:
+    process <file>          Process the specified file
+    batch <dir>             Process all files in directory
+    clean                   Clean up temporary files
+
+EXAMPLES:
+    $SCRIPT_NAME --verbose process input.txt
+    $SCRIPT_NAME --dry-run batch /path/to/files
+    $SCRIPT_NAME clean
+
+EOF
+}
+
+# Version information
+version() {
+    echo "$SCRIPT_NAME version $VERSION"
+}
+
+# Cleanup function (runs on EXIT)
+cleanup() {
+    local exit_code=$?
+    log_debug "Cleaning up..."
+    
+    # Remove temporary files
+    if [[ -n "${TEMP_FILE:-}" ]] && [[ -f "$TEMP_FILE" ]]; then
+        rm -f "$TEMP_FILE"
+    fi
+    
+    # Additional cleanup tasks here
+    
+    if [[ $exit_code -ne 0 ]]; then
+        log_error "Script failed with exit code $exit_code"
+    fi
+}
+
+# Error handler (runs on ERR)
+error_handler() {
+    local line_num=$1
+    log_error "Error occurred in script at line $line_num"
+}
+
+# Set up traps
+trap cleanup EXIT
+trap 'error_handler $LINENO' ERR
+
+# Command implementations
+cmd_process() {
+    local file=$1
+    
+    if [[ ! -f "$file" ]]; then
+        log_error "File not found: $file"
+        return 1
+    fi
+    
+    log_info "Processing file: $file"
+    
+    if [[ "$DRY_RUN" == true ]]; then
+        log_info "[DRY RUN] Would process: $file"
+        return 0
+    fi
+    
+    # Actual processing logic here
+    log_debug "Processing contents of $file"
+    
+    log_success "Successfully processed: $file"
+}
+
+cmd_batch() {
+    local dir=$1
+    
+    if [[ ! -d "$dir" ]]; then
+        log_error "Directory not found: $dir"
+        return 1
+    fi
+    
+    log_info "Batch processing directory: $dir"
+    
+    local count=0
+    while IFS= read -r -d '' file; do
+        if cmd_process "$file"; then
+            ((count++))
+        fi
+    done < <(find "$dir" -type f -name "*.txt" -print0)
+    
+    log_success "Processed $count files"
+}
+
+cmd_clean() {
+    log_info "Cleaning up temporary files..."
+    
+    if [[ "$DRY_RUN" == true ]]; then
+        log_info "[DRY RUN] Would remove temporary files"
+        return 0
+    fi
+    
+    # Clean up logic here
+    
+    log_success "Cleanup complete"
+}
+
+# Main entry point
+main() {
+    # Check if no arguments provided
+    if [[ $# -eq 0 ]]; then
+        usage
+        exit 1
+    fi
+    
+    # Parse command-line options
+    while [[ $# -gt 0 ]]; do
+        case $1 in
+            -h|--help)
+                usage
+                exit 0
+                ;;
+            -V|--version)
+                version
+                exit 0
+                ;;
+            -v|--verbose)
+                VERBOSE=true
+                shift
+                ;;
+            -d|--dry-run)
+                DRY_RUN=true
+                log_info "Dry run mode enabled"
+                shift
+                ;;
+            -l|--log)
+                if [[ -z "${2:-}" ]]; then
+                    log_error "Option --log requires an argument"
+                    exit 1
+                fi
+                LOG_FILE="$2"
+                shift 2
+                ;;
+            -*)
+                log_error "Unknown option: $1"
+                usage
+                exit 1
+                ;;
+            *)
+                # First non-option argument is the command
+                break
+                ;;
+        esac
+    done
+    
+    # Redirect output to log file if specified
+    if [[ -n "$LOG_FILE" ]]; then
+        exec 1> >(tee -a "$LOG_FILE")
+        exec 2> >(tee -a "$LOG_FILE" >&2)
+    fi
+    
+    # Get command
+    local command="${1:-}"
+    if [[ -z "$command" ]]; then
+        log_error "No command specified"
+        usage
+        exit 1
+    fi
+    shift
+    
+    # Execute command
+    case "$command" in
+        process)
+            if [[ $# -eq 0 ]]; then
+                log_error "process command requires a file argument"
+                exit 1
+            fi
+            cmd_process "$@"
+            ;;
+        batch)
+            if [[ $# -eq 0 ]]; then
+                log_error "batch command requires a directory argument"
+                exit 1
+            fi
+            cmd_batch "$@"
+            ;;
+        clean)
+            cmd_clean
+            ;;
+        *)
+            log_error "Unknown command: $command"
+            usage
+            exit 1
+            ;;
+    esac
+}
+
+# Run main function
+main "$@"