Bash Fundamentals Sequence #5: Utilizing Arrays in Bash

Within the earlier a part of the collection, you discovered about variables. The variables can have a single worth in it.

Arrays can have a number of values inside it. This makes issues simpler when it’s a must to take care of a number of variables at a time. You do not have to retailer particular person values in a brand new variable.

So, as an alternative of declaring 5 variables like this:

distro1=Ubuntu
distro2=Fedora
distro3=SUSE
distro4=Arch Linux
distro5=Nix

You possibly can initialize all of them in a single array:

distros=(Ubuntu Fedora SUSE "Arch Linux" Nix)

In contrast to another programming languages, you do not use commas as array aspect separators.

That is good. Let’s have a look at the best way to entry the array parts.

Accessing array parts in bash

The array parts are accessed utilizing the index (place within the array). To entry array aspect at index N, use:

${array_name[N]}

So, if you wish to print the SUSE, you will use:

echo ${distros[2]}

Entry all array parts without delay

For instance you need to print all the weather of an array.

It’s possible you’ll use echo ${array[n]} one after the other however that is actually not obligatory. There’s a higher and simpler manner:

${array[*]}

That will provide you with all of the array parts.

Get array size in bash

How are you aware what number of parts are there in an array? There’s a devoted solution to get array size in Bash:

${#array_name[@]}

That is so easy, proper?

Add array parts in bash

If it’s a must to add further parts to an array, use the += operator to append aspect to current array in bash:

array_name+=("new_value")

Here is an instance:

You too can use the index to set the aspect at any place.

array_name[N]=new_value

However keep in mind to make use of the right index quantity. In the event you apply it to an current index, the brand new worth will substitute the aspect.

In the event you use an ‘out of sure’ index, it would nonetheless be added after the final aspect. For instance, if the array size is six and also you attempt to set a brand new worth at index 9, it would nonetheless be added because the final aspect on the seventh place (index 6).

Delete an array aspect

You should use unset shell built-in to take away an array aspect by offering the index quantity:

unset array_name[N]

Here is an instance, the place I delete the 4th aspect of the array.

You too can delete all the array with unset:

unset array_name

🏋️ Train time

Let’s follow what you discovered about bash arrays.

Train 1: Create a bash script that has an array of 5 greatest Linux distros. Print all of them.

Now, substitute the center selection with Hannah Montanna Linux.

Train 2: Create a bash script that accepts three numbers from the consumer after which prints them in reverse order.

Anticipated output:

Enter three numbers and press enter
12 23 44
Numbers in reverse order are: 44 23 12

I hope you’re having fun with studying bash shell scripting with this collection. Within the subsequent chapter, you will find out about utilizing if-else. Keep tuned.