In this topic, we'll demonstrate the fundamentals of bash arrays and the way they're utilized in bash shell scripting.

An array is often defined as a set of comparable sorts of elements. Unlike most programming languages, arrays in bash scripting needn't be the gathering of comparable elements. Since Bash doesn't discriminate the string from variety, an array may contain both strings and numbers.

Bash doesn't provide support for the multidimensional arrays; we cannot have the weather which are arrays in themself. Bash offers assistance for one-dimensional numerically arranged arrays including associative arrays. To access the numerically indexed array from the last, we will use negative indices. The index of '-1' are going to be considered as a reference for the last element. we will use several elements in an array.

Bash Array Declaration

Arrays in Bash are often declared within the following ways:

Creating Numerically Indexed Arrays

We can use any variable as an indexed array without declaring it.

To explicitly declare a variable as a Bash Array, use the keyword 'declare' and therefore the syntax are often defined as:

declare -a ARRAY_NAME 

where,

ARRAY_NAME indicates the name that we might assign to the array.

Note: Rules of naming a variable in Bash are an equivalent for naming an array.

A general method to make an indexed array are often defined within the following form:

ARRAY_NAME[index_1]=value_1 

ARRAY_NAME[index_2]=value_2 

ARRAY_NAME[index_n]=value_n 

where keyword 'index' is employed to define positive integers.

Creating Associative Arrays

Unlike numerically indexed arrays, the associative arrays are firstly declared. we will use the keyword 'declare' and therefore the -A (uppercase) choice to declare the associative arrays. The syntax are often defined as:

declare -A ARRAY_NAME 

A general method to make an associative array are often defined within the following form:

declare -A ARRAY_NAME 

ARRAY_NAME[index_foo]=value_foo 

ARRAY_NAME[index_bar]=value_bar 

ARRAY_NAME[index_xyz]=value_xyz 

where index_ is employed to define any string.

We can also write the above form within the following way:

declare -A ARRAY_NAME 

 ARRAY_NAME=( 

 [index_foo]=value_foo 

 [index_bar]=value_bar 

 [index_xyz]=value_xyz 

) 

Bash Array Initialization

To initialize a Bash Array, we will use assignment operator (=), by specifying the list of the weather within parentheses, separated by spaces like below:

ARRAY_NAME=(element_1st element_2nd element_Nth) 

Note: Here, the primary element will have an index of 0. Also, there should be no space round the assignment operator (=).

Access Elements of Bash Array

To access the weather of a Bash Array, we will use the subsequent syntax:

echo ${ARRAY_NAME[2]} 

Print Bash Array

We can use the keyword 'declare' with a '-p' choice to print all the weather of a Bash Array with all the indexes and details. The syntax to print the Bash Array are often defined as:

declare -p ARRAY_NAME 

Array Operations

Once an array is assigned, we will perform some useful operations thereon . we will display its keys and values also as modify them by appending or removing the elements:

Reference Elements

To reference one element, we are required to understand the index of the element. we will reference or print any element using the subsequent syntax:

${ARRAY_NAME[index]} 

Note: Curly braces ${} are required to avoid shell's filename expansion operators.

Example of declaration:

#!/bin/bash  
#Script to print an element of an array with an index of 2  
  
#declaring the array  
declare -a example_array=( "Welcome""To""Great" "Learning" "Academy" )  
  
#printing the element with index of 2  
echo ${example_array[2]}  

The Output of the above code.

Conclusion:

Similarly, we can use these bash commands while creating our own bash script.