linux用户添加、删除、添加附属组、移出附属组

#!/bin/bash

function print_usage()
{
    echo "./userM.sh -A <username>  添加用户" 
    echo "./userM.sh -MG <username> 添加到root组"
    echo "./userM.sh -DG <username> 从root组移除"
    echo "./userM.sh -l <username>  列出用户所在组"
    echo "./userM.sh -lall          列出所有用户名"
}


function u_add()
{
    u_name=${1}
    u_pass=${2}
    useradd ${u_name}
    echo ${u_pass} | passwd --stdin ${u_name}
}

function u_add_to_groupRoot()
{
    if [ "" == "$1" ] ; then
        print_usage
        return
    fi

    u_name=${1}
    #把用户加入root组
    # usermod -G root ${u_name}
    gpasswd -a ${u_name} root
}

function u_del_from_groupRoot()
{
    if [ "" == "$1" ] ; then
        print_usage
        return
    fi
    u_name=${1}
    #把用户从root组删除
    gpasswd -d ${u_name} root
}

function u_groups()
{
    if [ "" == "$1" ] ; then
        print_usage
        return
    fi
    u_name=${1}
    groups ${u_name}
}

function u_list_alluser()
{
        # 删除bin行tcpdump之间的所有行
    #compgen -u | sed '/^bin$/,/^tcpdump$/d'
    compgen -u | sed '/^bin$/,/^shareadmin$/d'
}

opttype=$1
username=$2


case ${opttype} in
    -A) # 添加用户
    u_add ${username} root@1234
        ;;
    -MG) # 修改组
        u_add_to_groupRoot ${username}
        ;;
    -DG) # 修改组
        u_del_from_groupRoot ${username}
        ;;
    -l)
        u_groups ${username}
        ;;
    -lall)
    u_list_alluser
        ;;
    *)
        print_usage
        ;;
esac