有时需要检查哪个用户正在执行bash脚本，以及用户是否提供了所有必需的参数：

#!/bin/bash 

display_usage() { 
	echo "This script must be run with super-user privileges." 
	echo -e "\nUsage: $0 [arguments] \n" 
	} 
# if less than two arguments supplied, display usage 
	if [  $# -le 1 ] 
	then 
		display_usage
		exit 1
	fi 

# check whether user had supplied -h or --help . If yes display usage 
	if [[ ( $# == "--help") ||  $# == "-h" ]] 
	then 
		display_usage
		exit 0
	fi 

# display usage if the script is not run as root user 
	if [[ "$EUID" -ne 0 ]]; then 
		echo "This script must be run as root!" 
		exit 1
	fi 

echo "All good !!!"

输出：

$./script.sh 1 
This script must be run with super-user privileges.
Usage: ./script.sh [arguments] 
$su
Password: 
# ./script.sh 1 2
All good !!!