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Arrays are a common part of any programming language. In Bash scripts, you can also use arrays; you can declare, modify, and manipulate arrays.

But in this article, we will see step by step how to declare an array and add new data to it. We will see two different ways of adding new data in an array.

Furthermore, we will see necessary examples and explanations to make the topic easier to understand.

Declaring an array in Bash

This is the first step. In this step, we will see how to declare an array in Bash.

The general syntax for declaring an array is:

ArrayName=('Data1' 'Data2' 'Data3')

Below, we declare an empty array with the following code:

MyArray=()

Use the += operator in Bash to append data to an array without specifying an index

We have already created an array, so now we will enter some data. This section will show how we can append data to an array without an index.

The general syntax for this purpose is:

ArrayName+=('Your Data')

In the following example, we will include three data in the array. The code for our example is:

MyArray=()
MyArray+=('A')
MyArray+=('B')
MyArray+=('C')
echo "Current array elements are: ${MyArray[@]}"

In the above example, we first declared an array, then included the data in the array one by one. Finally, we just displayed all the data in an array.

Now, after executing the above code example, you will get an output as shown below:

Current array elements are: A B C

Alternative way to append data to an array without specifying index in Bash

In this method, we will see another alternative to include data in an array without indexing. In the following example, we will include some data in an array without indexing.

The code for our example is as follows:

MyArray=('A' 'B' 'C')
MyArray=(${MyArray[@]} 'D')
MyArray=(${MyArray[@]} 'E')
MyArray=(${MyArray[@]} 'F' 'G')
echo "Current array elements are: ${MyArray[@]}"

In the example, we MyArray=('A' 'B' 'C')declared an array with some data via the line . After that, we included all the data one by one.

Notice that in ${MyArray[@]}the section we append all the previous data to the new data. This is how we repeatedly declare arrays and update data.

Now after executing the above code sample. You will get the following output:

Current array elements are: A B C D E F G

The two methods discussed above are the most reliable ways to append data to an array without indexing.