01.Declaring_and_accessing_arrays.md

Declaring and Accessing Arrays in Linux Scripting

Arrays in Linux scripting provide a convenient way to store and manipulate multiple values. This tutorial will guide you through the process of declaring arrays, initializing them, and accessing their elements in a Linux environment.

Declaring Arrays

In Bash scripting, arrays can be declared using the following syntax:

# Method 1: Using parentheses
my_array=(value1 value2 value3)

# Method 2: Using the `declare` command
declare -a my_array=("value1" "value2" "value3")

Here, my_array is the name of the array, and value1, value2, and value3 are the elements of the array. Arrays can store a mix of data types, including strings and numbers.

Initializing Arrays

Arrays can be initialized with values during declaration or later in the script:

# Initializing during declaration
my_array=("apple" "banana" "cherry")

# Initializing later in the script
my_array[3]="date"
my_array[4]="fig"

Accessing Array Elements

To access individual elements of an array, use the index enclosed in square brackets:

echo "First element: ${my_array[0]}"
echo "Second element: ${my_array[1]}"

Array Length

To find the length of an array, use the # symbol:

array_length=${#my_array[@]}
echo "The length of the array is: $array_length"

Iterating Over Arrays

You can use loops to iterate over array elements:

# Using for loop
for element in "${my_array[@]}"; do
    echo "$element"
done

# Using for loop with index
for ((i=0; i<${#my_array[@]}; i++)); do
    echo "Element $i: ${my_array[$i]}"
done

Slicing Arrays

You can extract a subset of elements from an array using slicing:

# Extracting elements from index 1 to 3
subset_array=("${my_array[@]:1:3}")
echo "Subset array: ${subset_array[@]}"

Conclusion

Declaring and accessing arrays in Linux scripting is a fundamental skill that allows you to work with multiple values efficiently. Whether you need to store a list of filenames, command-line arguments, or any other set of related data, arrays provide a versatile solution. Incorporate these array-handling techniques into your scripts to enhance their flexibility and readability.

Next | Array manipulation