Arrays can be defined using different techniques:

1. Define an array using a list of values in a single line:

        array_var=(test1 test2 test3 test4)
        #Values will be stored in consecutive locations starting 
        from index 0.

Alternately, define an array as a set of index-value pairs:

        array_var[0]="test1"
        array_var[1]="test2"
        array_var[2]="test3"
        array_var[3]="test4"
        array_var[4]="test5"
        array_var[5]="test6"

2. Print the contents of an array at a given index using the following commands:

        echo ${array_var[0]}
        test1
        index=5
        echo ${array_var[$index]}
        test6

3. Print all of the values in an array as a list, using the following commands:

        $ echo ${array_var[*]}
        test1 test2 test3 test4 test5 test6

  Alternately, you can use the following command:

        $ echo ${array_var[@]}
        test1 test2 test3 test4 test5 test6

4. Print the length of an array (the number of elements in an array):

        $ echo ${#array_var[*]}6