Arrays in Bash

Manage collection of entries

Create Array

array_name=value

:::info Every Bash variable is an array with single element :::

array_name=(val1 val2 val3 …)

or

declare -a fruits=(val1 val2 val3)

echo ${fruit[0]} or echo ${fruit}

echo ${fruit[-1]}

:::info This will not work with array echo $fruit[0] always need to use { and } :::

echo ${fruit[@]} or echo ${fruit[*]}

:::info using variable fruit[@] is recommended
This will print variables values with spaces as one string

But fruit[*] will print it as two different strings :::

array[1]=’value’

Modifying last element of array

array[-1]=”value”

echo "${#fruits[@]}"

This will print the length of array

array+=(new_val)

unset array[2]

This will remove 3rd element; the next elements will not replace the removed element.

:::info The deleted element will be empty and will not get replaced :::

IF array is array=(value1 value2 value3 value4)

Then printing a portion of array is array slicing

This can be done like this: echo “${array[@]:1:2}“ this will print 2nd and 3rd element.

array_copy=(“${array[@]”)

array_append=(“${array[@]}” “val1” Val2” )

array_append=(“val1” val2 “${array[@]}” “val3”)

array_append=(“${array1[@]}” “${array2[@}}”)

for element in "${array[@]}"; do
    echo "${element}"
done

select element in "${array[@]}" "quit"; do
    [[ "${fruit}" == "quit" ]] && break
    echo "${array}"
done