#!/bin/sh
#set -x
out=hosts.dns
echo -e "##### `date`\n127.0.0.1\tlocalhost\n##### from dns">$out
{
	cat /etc/hosts
	egrep '^[a-zA-Z0-9]' tw.hosts
	echo "ls math.duke.edu"|nslookup
	echo "ls xxxx.duke.edu"|nslookup
	echo "ls yyyy.duke.edu"|nslookup
} |
awk '{
	if($1 ~ /^(152|127)/){# hosts table: ip nickname officalname comments
		if(!N[$2]){N[$2]=$1;} # pick the 1st one only
		for(i=3;i<=NF;i++){
			if(!F[$i] && $i ~ /\./){F[$i]=$2;break;}
		}
	}else if ($NF ~ /^\//){ # tw.hosts: hostname ostype dir
		if(!N[$1] && !F[$1]){ # not in host table
			TM[++tm]=$1;
		}
		TN[$1]=1;
	}else if ($1 ~ /ORIGIN/ && $2 ~ /\.$/){ # nslookup: $ORIGIN domain
		dnm=substr($2,1,length($2)-1);
		printf("##### %s\n",dnm)>>h;
	}else if ($NF ~ /^152/ && $1 ~ /^[a-zA-Z][a-zA-Z0-9]*$/){ # nslookup: nickname ip
		fn=$1 "." dnm;
		if(!N[$1]){# nickname not in hosts table
			M[++m]=$NF "\t" $1 " " fn;
		}else if(N[$1] != $NF){ # nicks IP differ  # !G[$1] && 
			ID[$1]=$NF;
		}
		G[$1]=1;
		if(!TN[$1] && !TN[fn]){
			DN[++dn]=$1 "\t\t" fn;
		}
		printf("%s\t%s %s\n",$NF,$1,fn)>>h;
	}
}END{
	printf("##### NOT IN HOST TABLE:\n");
	for(i=1;i<=m;i++){
		printf("%s\n",M[i]);
	}
	
	printf("##### IP IN HOST TABLE DIFF FROM DNS:\n");
	for(i in ID){
		printf("%s\t%s <- %s\n",N[i],i,ID[i]);
	}
	
	printf("##### EXTRA HOSTNAMES IN HOST TABLE:\n");
	for(i in N){
		if(!G[i] && N[i]){ printf("%s\t%s\n",N[i],i); }
	}
	
	printf("##### TW.HOSTS NOT IN HOST TABLE:\n");
	for(i=1;i<=tm;i++){
		printf("%s\t%s\n",N[TM[i]],TM[i]);
	}
	
	printf("##### DNS HOSTS NOT IN TW.HOSTS:\n");
	for(i=1;i<=dn;i++){
		printf("%s\n",DN[i]);
	}
	
}' h=$out -

mv $out $out.$$ && sort -t. +0n -1 +1n -2 +2n -3 +3n -4 $out.$$ >$out && rm -f $out.$$