Bash Script: Create & Use Associative Array like Hash tables

Before using Associative Array features make sure you have bash version 4 and above, use command "bash --version" to know your bash version.

Below shell script demonstrate  the usage of associative arrays, feel free to copy and use this code.

Associative arrays are created using declare -A name

Source: cat associative_array.sh
#!/bin/bash

# use -A option declares associative array
declare -A array

# Here, you can have some other process to fill up your associative array.
array[192.168.1.1]="host1"
array[192.168.1.2]="host2"
array[192.168.1.3]="host3"
array[192.168.1.4]="host4"
array[192.168.1.5]="host5"

echo -n "Enter the ip address to know the hostname: "
read ipaddress

# Now you can use the associative array as hash table, (key,value) pairs.
echo "Hostname associated with the $ipaddress is: ${array[$ipaddress]}"

# You can also perform all the basic array operation.
# Iterate over Associative Arrays

#for hostname in "${array[@]}"; do
#       echo $hostname
#done

Output: ./associative_array.sh 

Enter the ip address to know the hostname: 192.168.1.4

Hostname associated with the 192.168.1.4 is: host4