#! /bin/bash #list user who belong to more than one group #and list user who belong to the group which isn't the same as the username #w is whitelist,we will not think user in this whitelist is special or dangerous w=("root" "adm" "games" "operator" "halt" "shutdown" "sync" "daemon" "bin" "operator") function WhiteList() {     for i in ${w[@]}     do        if [ "$i" == "$1" ];then            return 1         fi    done    return 0 } IFS=" " for LINE in `cat /etc/passwd|awk -F: '{print $1}'` do    WhiteList $LINE;     #if $? equal 1,means it is in the whitelist     if [ $? -eq 0 ];then        a=`groups $LINE|awk -F: '{print $2}'`         b=`echo $a`         if [ "$b" != "$LINE" ];then            #echo $LINE             echo `groups $LINE`         fi    fi done