Bash arrays
Bash arrays are one dimensional variables. They may be one of two types, indexed or associative. Indexed arrays have integer keys and associative arrays have string keys. Values for both are strings. (Other languages call an associative array a “dictionary”, “hash”, or “map”.) Initializing Indexed arrays are declared using declare -a, but can also be implicitly declared (in the global scope) using ARRAY[subscript], where subscript is an arithmetic expression. For this reason, associative arrays must be explicitly declared using declare -A. Initial values may optionally be defined at declaration. The -p option to the declare builtin will print the full variable, including type, keys, and values. ...