How to run shell script array in Ubuntu terminal?

Question

I am learning shell script language. I write and run the code using Ubuntu terminal.I have declare an array with value like below..

arr=(1 2 3)
echo $(arr[0])
echo $(arr[1])
echo $(arr[2])

The above code doesn't run.Whenever I run using the terminal,I face error like below..

./a.sh: line 2: arr[0]: command not found
./a.sh: line 3: arr[1]: command not found
./a.sh: line 4: arr[2]: command not found

How can I solve it?

Answer 1

The syntax $(...) is for executing sub-shell commands.

Use syntax ${...} to read variable content. So:

arr=(1 2 3)
echo ${arr[0]}
echo ${arr[1]}
echo ${arr[2]}