Indexed and associative arrays

Bash provides one-dimensional indexed and associative array variables: any variable may be used as an indexed array, declare -a name declares one explicitly, and declare -A name creates an associative array. There is no maximum limit on size and no requirement that members be indexed or assigned contiguously. Indexed arrays are zero-based, and a negative subscript counts back from one greater than the maximum index, so -1 references the last element. Assigning name[subscript]=value automatically creates an indexed array; compound assignment name=(value1 value2 ...) assigns many elements at once, and when no subscript is supplied each element takes the last assigned index plus one. Reference elements as ${name[subscript]} — the braces are required to avoid conflicts with filename expansion. A subscript of @ or * expands to all members; double-quoted, ${name[@]} expands each element to a separate word while ${name[*]} joins members into a single word separated by the first character of IFS. ${#name[@]} is the element count and ${!name[@]} expands to the assigned indices. unset name[subscript] removes one element; unset name removes the entire array. Scope: Bash. Reviewed October 4, 2026.