用Bash脚本将Linux普通用户添加为系统管理员

#!/bin/bash

script_name="add_admin.sh"
script_usage=$(cat <<EOF
$script_name [USER NAME]
EOF
)
script_function=$(cat <<EOF
This script is used to add the current or specified users as system administrator.
EOF
)
script_doc=$(cat <<EOF
-h     Display this help.
EOF
)
script_examples=$(cat <<EOF
EOF
)
state_prefix="==="
warning_prefix="***"
error_prefix="!!!"

function display_help() {
    if [ -n "$script_usage" ]; then
    echo -e "Usage: $script_usage"
    fi
    
    if [ -n "$script_function" ]; then
    echo -e "$script_function"
    fi
    
    if [ -n "$script_doc" ] ; then
    echo -e "\n$script_doc"
    fi
    
    if [ -n "$script_examples" ]; then
    echo -e "\nExamples"
    echo -e "$script_examples"
    fi
}

function add_to_groups() {
    the_user="$1"
    shift 1

    for the_group in "$@" ; do
        if [ -n "`cat /etc/group | grep $the_group`" ]; then
            if [ -n "`groups $the_user | grep $the_group | cut -d ‘:‘ -f 2`" ]; then 
                echo "$warning_prefix User ‘$the_user‘ has already been in the group ‘$the_group‘!"
            else
                sudo usermod -a -G $the_group $the_user
                echo "$state_prefix User ‘$the_user‘ has been added to the group ‘$the_group‘!"
            fi
        else
            echo "$warning_prefix The group ‘$the_group‘ does not exist!"
        fi
    done
}

# Process command options
while getopts ":h" opt; do
    case $opt in
    h  )  display_help
        exit 0 ;;
    \? )  display_help
        exit 1 ;;
    esac
done
shift $(($OPTIND - 1))

admin_groups="adm dialout fax cdrom floppy tape sudo audio dip video plugdev netdev bluetooth lpadmin fuse scanner powerdev burning"

# Start execute the command
if [ $OSTYPE = ‘linux-gnu‘ ]; then
    # Get the user name
    if [ -n "$*" ]; then
        for the_user in "$@" ; do
            if [ -n "`cat /etc/passwd | grep $the_user | cut -d ‘:‘ -f 1`" ]; then
                add_to_groups $the_user $admin_groups
                echo "$state_prefix User ‘$the_user‘ has been set as administrator!"
            else
                echo "$warning_prefix ‘$the_user‘ is not a valid user!"
            fi
        done
    else
    the_user=`whoami`
        echo "$state_prefix The current logged-on user ‘$the_user‘ will be set as administrator!"    
        add_to_groups $the_user $admin_groups
        echo "$state_prefix User ‘$the_user‘ has been set as administrator!"
    fi
    exit 0
fi

echo "$warning_prefix Operating system or host name is not supported!"