Bash Arrays

Bash Array

Bash Array – An array is a collection of elements. Unlike in many other programming languages, in bash, an array is not a collection of similar elements. Since bash does not discriminate string from a number, an array can contain a mix of strings and numbers.

Bash Array Tutorials

The following tutorials deal with the individual concepts of an array in details with well explained examples.

Basics

• Bash – Initialize Array
• Bash – Length/Size of Array
• Bash – Access Elements(s) of Array using Index
• Bash – Print All Elements of Array in Single Line to Console

Looping Scenarios

• Bash – Loop through Array Elements
• Bash – Loop through Array Indices
• Bash Array – While Loop
• Bash Array – For Loop

Find / Check

• Bash – Find the index of specific element in Array

Modifications

• Bash – Update Element of an Array at Specific Index
• Bash – Append Element(s) to Array
• Bash – Append an Array to another Array
• Bash – Slice an Array

Bash Array Declaration

To declare a variable as a Bash Array, use the keyword declare and the syntax is

 declare -a arrayname

Example

In the following script, we declare an array with name fruits.

 declare -a fruits

Bash Array Initialization

To initialize a Bash Array, use assignment operator =, and enclose all the elements inside braces (). The syntax to initialize a bash array is

 arrayname=(element1 element2 element3)

Example

In the following script, we initialize an array fruits with three elements.

fruits=("apple" "banana" "cherry")

Access elements of Bash Array

We can access elements of a Bash Array using the index.

 echo ${ARRAY_NAME[2]}

Example

In the following script, we access elements of array fruits with indices.

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

Print Bash Array with Indices and Details

To print all the elements of a bash array with all the index and details use declare with option p.

 declare -p arrayname

Example

fruits=("apple" "banana" "cherry")
declare -p fruits

Output

declare -a fruits='([0]="apple" [1]="banana" [2]="cherry")'

Loop through Elements of Array using For Loop

We can loop through elements of array using for loop, as shown in the following example.

Example

fruits=("apple" "banana" "cherry")
for element in "${fruits[@]}";
do
    echo $element
done

Output

apple
banana
cherry

Conclusion

Concluding this Bash Tutorial, we have learnt how to declare, initialize and access Bash Arrays, with the help of examples.