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Sorting an array is a very common task in any programming language. In Bash scripting, we can also accomplish this task in two different ways.

The first one uses any sorting algorithm and the second one uses a built-in keyword in Bash script called readarray. This article will show how we can sort an array in Bash script.

Furthermore, we will see some examples with explanations to make the topic easier to understand.

Sort an array using bubble sort in Bash

In Bash scripting, you can sort an array using any sorting algorithm like bubble sort, merge sort, etc. In our example below, we have implemented bubble sort to sort the array.

The code for our example is shown below.

MyArray=(9 8 20 10 15)

echo "The original array is:"
echo ${MyArray[*]}

# We implemented the bubble sort here.
for ((i = 0; i<5; i++))
do

    for((j = 0; j<5-i-1; j++))
    do

        if [ ${MyArray[j]} -gt ${MyArray[$((j+1))]} ]
        then
            # swap
            temp=${MyArray[j]}
            MyArray[$j]=${MyArray[$((j+1))]}
            MyArray[$((j+1))]=$temp
        fi
    done
done

echo "The sorted array is:"
echo ${MyArray[*]}

Let's explain the above example line by line.

1. First, we declared an array called MyArray.
2. After that, we echo ${MyArray[*]}display the array via rows.
3. After that, we created two loops and implemented bubble sort. In these loops, we created a condition to check whether the current element is greater than the next element.
4. If the condition is true, then we perform a swap operation between those two elements of the array.
5. Finally, we just display the array after the sorting is done. When you run the above program, you will get the output as shown below.

The original array is:
9 8 20 10 15
The sorted array is:
8 9 10 15 20

Sorting an array using readarray keyword in Bash

Suppose you have an array that contains a mixture of alphabetical and numeric characters. To sort this array, you need to find different ways to do it.

To sort the array, you need to compare the ASCII values ​​of the characters.

There is a built-in keyword in Bash scripting that allows you to do this in just one line of code. The keyword is readarray.

In the following example, we have created an array of combined alphabetical and numeric characters. After we sort the array using the readarray keyword, we display the sorted array.

The code for our example is shown below.

MyArray=(n a c b 6 7 5)
readarray -t MyArray < <(printf '%s\n' "${MyArray[@]}" | sort)
echo "The sorted list is: ${MyArray[*]}"

After executing the script, you will get the output as shown below.

The sorted list is: 5 6 7 a b c n

请注意, all the codes used in this article are written in Bash. It will only work in Linux Shell environment.