#!/bin/bash
Check_user()
{
    UserName=$1
    AllUsers=$(cat /etc/passwd | awk -F: ‘{print $1}‘)
    for i in $AllUsers
    do
        if [ "$i" = "$UserName" ];then
            return 1
        else
            continue
        fi
    done
    return 0
}
Main()
{
    for i in $@
    do
        if `Check_user $i`;then
            useradd $i
            echo "$i create ok"
        else
            echo "$i is already exsists"
        fi
    done
}
Main $*;
原文:http://www.cnblogs.com/blog-acf/p/4265655.html