Shell Programming and Scripting

#!/bin/bash
CONFIG_FILE="conf.cfg"
TEMP_HOSTNAME="temp_file1.txt"

for IP in `egrep -o '([0-9]{1,3}\.){3}[0-9]{1,3}' $CONFIG_FILE`
do
        ssh "$IP" 'hostname' > $TEMP_HOSTNAME
        REMOTE_HOSTNAME=$(cat "$TEMP_HOSTNAME")
        echo ""$IP" "$REMOTE_HOSTNAME"" >> temp_file2.txt
done

TEMP_HOSTNAME=$(ssh "$IP" 'hostname')

# declaration (important! automatic created, undeclared arrays or numeric-indexed arrays)
declare -A temphosts

# assignment
temphosts[$IP]="$TEMP_HOSTNAME"

# access it again:
echo ${temphosts[$IP]}

# iterate over associative array
for idx in ${!temphosts[@]} ;do echo ${temphosts[$idx]};done

for IP in $(egrep -o '([0-9]{1,3}\.){3}[0-9]{1,3}' $CONFIG_FILE)
  do    echo ""$IP" $(ssh "$IP" 'hostname')  >> temp_file2.txt
  done