How to get all the keys in an associative array in Bash?

How to get all the keys of an associative array in Bash?

There are at least 2 ways to get the keys from an associative array of Bash. Let’s start with an example associative array:

$ declare -A aa
$ aa["foo"]=bar
$ aa["a b"]=c

We can use the @ special index to get all the keys and store them in an array:

$ aakeys=("${!aa[@]}")

The array content is all the keys (note the key "a b" has a space within itself):

$ echo ${aakeys[*]}
foo a b

Another more convenient way to operate on the keys from an associative array is to loop the keys as follows:

$ for key in "${!aa[@]}"; do echo $key; done
foo
a b

The spaces are well handled in the for loop.