Parse Command-Line Arguments with Getopts for Flexible Bash Scripts

#!/bin/bash

# Default values
VERBOSE=false
ENVIRONMENT="development"
OUTPUT_FILE="output.txt"

# Usage function
usage() {
    echo "Usage: $0 [-v] [-e <environment>] [-o <output_file>]"
    echo "  -v: Enable verbose output"
    echo "  -e <environment>: Set the environment (e.g., production, staging)"
    echo "  -o <output_file>: Specify an output file path"
    exit 1
}

# Parse options using getopts
# v: no argument
# e: requires an argument
# o: requires an argument
while getopts "ve:o:" opt; do
    case "$opt" in
        v)
            VERBOSE=true
            ;;
        e)
            ENVIRONMENT="$OPTARG"
            ;;
        o)
            OUTPUT_FILE="$OPTARG"
            ;;
        \?) # Invalid option
            usage
            ;;
    esac
done

# Shift positional parameters so that $1 refers to the first non-option argument
shift $((OPTIND-1))

echo "Script execution with parameters:"
echo "Verbose mode: $VERBOSE"
echo "Environment: $ENVIRONMENT"
echo "Output File: $OUTPUT_FILE"

# Example of using a positional argument (if any)
if [ -n "$1" ]; then
    echo "First positional argument: $1"
fi

# Example logic based on parsed arguments
if $VERBOSE; then
    echo "Verbose output enabled: Performing detailed operations..."
fi

if [ "$ENVIRONMENT" == "production" ]; then
    echo "Running in PRODUCTION environment."
else
    echo "Running in $ENVIRONMENT environment."
fi

echo "Results will be written to $OUTPUT_FILE"
# echo "Some actual script logic writing to $OUTPUT_FILE..." > "$OUTPUT_FILE"