Let’s dive deeper into using Bash arrays in scripting, their operations, and practical use case examples.<\/p>
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What is a Bash array?<\/h2>
A Bash array is a data structure designed to store information in an indexed way. In other words, a Bash array is a large group of variables. Unlike typical arrays used in other programming languages, arrays can store different types of elements. For example, you can use a bash array to store both strings and numbers.<\/p>
Note that bash does not support multidimensional arrays, so it’s not possible to add an array within an array.<\/p>
There are two types of bash arrays: indexed <\/strong>and associative<\/strong>. An indexed<\/strong> array is referred to by integers or numbers, which helps organize basic data. Meanwhile, an associative<\/strong> array is referred to via strings or a set of characters and words, suitable for storing key-value pairs.<\/p> Apart from the reference, the method of writing indexed and associative arrays also slightly differs. <\/p> Declaring a Bash array essentially means creating the index and assigning elements to it. You can also explicitly declare an array by adding the shell builtin declare<\/strong> with the -a<\/strong> flag at the beginning of your Bash script, though it’s optional in some scenarios.<\/p> For example, declaring an indexed array doesn’t need the shell builtin, but it’s mandatory if you want to declare an associative array. Apart from this rule, you can declare either arrays using the same syntax, which we’ll explain next. <\/p> The basic syntax of a Bash array looks like the following:<\/p> Subscript<\/strong> is the reference to your array elements, which are numbers<\/strong> for indexed arrays and strings<\/strong> for the associative ones. Here’s an example of an actual indexed Bash array:<\/p> Meanwhile, an associative Bash array looks like this:<\/p> You can also simplify arrays by writing them in a single line using indices, like in these examples:<\/p> Note that the first example encloses the array elements in quotation marks. This is optional, but becomes necessary when the items are space-separated strings or an empty string. <\/p> For indexed arrays specifically, you can omit the subscript when writing it in a single line because Bash automatically assigns the number at a fixed increment:<\/p> Remember that indexing starts at 0<\/strong>, so the above example will assign the car <\/strong>element of the array to the 0<\/strong> index.<\/p> Another interesting feature of bash arrays is that following index numbers in order is not necessary. For example, you can declare only the first and third elements while leaving the second element of an array empty:<\/p> Now that we know how to declare an array, let’s learn about different operations for Bash array manipulation.<\/p>How do you declare a Bash array?<\/h2>
Syntax overview<\/h3>
#optional for indexed\ndeclare -a IndexedArray\nArray[subscript1]=element1\nArray[subscript2]=element2\nArray[subscript2]=element3<\/pre>
#optional for indexed\ndeclare -a IndexedArray\nIndexedArray[0]=car\nIndexedArray[1]=plane\nIndexedArray[2]=bike<\/pre>
declare -a IndexedArray\nAssociativeArray[color]=blue\nAssociativeArray[type]=car\nAssociativeArray[topspeed]=200<\/pre>
IndexedArray=([0]='car' [1]='plane' [2]='bike')<\/pre>
declare -A Associative Array=( [color]=blue [type]=car [topspeed]=200 )<\/pre>
IndexedArray=(car plane bike)<\/pre>
IndexedArray[0]=car\nIndexedArray[2]=bike<\/pre>
How do you add a variable to a Bash array?<\/h2>
![\"Bash](\"\/tutorials\/wp-content\/uploads\/sites\/2\/2022\/05\/Bash-script-to-create-and-print-out-an-indexed-array-1.png\")