#!/bin/bash
#set -x
MAX=255
FILE=$1.dns_list
#declare -a d_arr

if [ -z "$1" ]
then
echo "Usage: `basename $0` network"
echo " e.g.`basename $0` 1.1.1"
exit
fi

echo "Remove file $FILE..."
rm $FILE

for (( i = 1; i < $MAX; i++ ))
do
PARSE=$(host $1.${i})
if [ $? = 0 ]
then
echo "$PARSE" " $1.$i" >> $FILE
fi
done

cat $FILE | while read i
do
declare -a d_arr
ln=`echo $i | awk '{printf $5 "\t : \t" $6}' |sed 's/\.XYZ\.com\.//g'`
cnt=${#d_arr[@]}
let c=$cnt
d_arr[$c]=$ln # <<---<< I think I need double substitution for this stmt
echo ${d_arr[$c]}
done

# For some reason the array does not exist
cnt1=${#d_arr[@]}
echo "The size of d_arr: $cnt1"
echo "The array ${d_arr[@]}"
exit

Hi,

How do I perform double substitution in bash?

I try to write a bash script to list all the DNS entry from a subnet e.g. 192.168.1.0/24 and store the valid DNS entry into an array ${d_arr[]},
The variable d_arr[$c] works fine in while read i loop, but once the loop finished, array ${d_arr[]} is empty, I have tried he following:

let ${d_arr[$c]}=$ln

but get a syntax error.

How do I get it store into an array for the duration when he program is still running?

Thanks,
-Fu