Arrays Bash provides one-dimensional array variables. There is no maximum limit on the size of an array, nor any requirement that members be indexed or assigned contiguously. Arrays are zero-based. Attributes may be specified for an array variable using the declare and readonly builtins. Each attribute applies to all members of an array.
Indexing starts at zero.
This syntax is also accepted by the declare builtin. The braces are required to avoid conflicts with the shell's filename expansion operators. These subscripts differ only when the word appears within double quotes. Referencing an array variable without a subscript is equivalent to referencing element zero. The unset builtin is used to destroy arrays.