Bash Exercises Part 1

arr[1]+=foo appends the string “foo” to the value in arr[1], so it becomes “schemefoo”. The contents of arr at this point becomes:

$ printf '%s\n' "${arr[@]}"
lisp
schemefoo
haskell

When we assign “javascript” to arr[1] it works fine because we are assigning a new literal string to that array index, and it is valid to do that. The index 1 now has the new string “javascript” instead of the original string “scheme”.

On the other hand, arr[2]=(javascript) is an error

“bash: arr[2]: cannot assign list to array member”

Using the syntax (value) on the right-hand side of an assignment tells bash it is an array, and as bash does not support multidimensional arrays, it is not legal to try to add an array to a given index. In this case, the original string “haskell” is still present in arr[2].

The contents of the array is:

$ printf '%s\n' "${arr[@]}"
lisp
javascript
haskell