Indexed array declaration in Bash Scripting - Step-by-Step Execution

Concept Flow - Indexed array declaration

Start script

↓

Declare indexed array

↓

Assign values to array elements

↓

Access or print array elements

↓

End script

This flow shows how a bash script declares an indexed array, assigns values, and accesses them.

Execution Sample

Bash Scripting

fruits=("apple" "banana" "cherry")
echo ${fruits[0]}
echo ${fruits[1]}
echo ${fruits[2]}

Declare an indexed array named fruits with three elements and print each element.

Execution Table

Step	Action	Array State	Output
1	Declare array fruits with elements apple, banana, cherry	["apple", "banana", "cherry"]
2	Print fruits[0]	["apple", "banana", "cherry"]	apple
3	Print fruits[1]	["apple", "banana", "cherry"]	banana
4	Print fruits[2]	["apple", "banana", "cherry"]	cherry
5	End of script	["apple", "banana", "cherry"]

💡 All array elements accessed and printed, script ends.

Variable Tracker

Variable	Start	After Declaration	Final
fruits	undefined	["apple", "banana", "cherry"]	["apple", "banana", "cherry"]

Key Moments - 2 Insights

Why do array indices start at 0 in bash?

Bash arrays are zero-indexed, so the first element is at index 0 as shown in execution_table steps 2-4.

What happens if I try to access an index that was not assigned?

Accessing an unassigned index returns an empty string, because only declared indices hold values, as seen in the array state in execution_table.

Visual Quiz - 3 Questions

Look at the execution table, what is the output at step 3?

A banana

B apple

C cherry

D undefined

💡 Hint

Check the Output column for step 3 in the execution_table.

At which step is the array fruits declared?

A Step 3

B Step 2

C Step 1

D Step 4

💡 Hint

Look at the Action column to find when the array is first created.

If you add a new element fruits[3]="date", what will be the array state after declaration?

A ["apple", "banana", "cherry"]

B ["apple", "banana", "cherry", "date"]

C ["date"]

D undefined

💡 Hint

Adding an element at index 3 appends it to the array, expanding its state.

Concept Snapshot

Indexed array declaration in bash:
fruits=("apple" "banana" "cherry")
Access elements by index: ${fruits[0]}
Indices start at 0
Unassigned indices return empty
Use parentheses to declare arrays

Full Transcript

This lesson shows how to declare an indexed array in bash scripting. The array named fruits is created with three elements: apple, banana, and cherry. Each element is accessed by its index starting at zero. The script prints each element in order. The array state remains the same throughout the script. Beginners often wonder why indices start at zero and what happens if an index is not assigned. The answer is that bash arrays are zero-indexed and unassigned indices return empty strings. Adding new elements expands the array. This visual trace helps understand how arrays work step-by-step.