Bash：关联数组的值可以是数组吗？ 它的语法是什么？

Question

I have an associative array stored in a bash file, and I'd like the values of said associative array to be arrays, but I don't even know if that's possible:

Let's say I have the file /tmp/conf.bash containing:

declare -A ASSOCIATIVE=( ["foo"]=( "bar" "baz" ) ) When I tried to load it (using source /tmp/conf.bash ) I get:

borrajax@wharrgarbl:~# source /tmp/conf.bash bash: /tmp/conf.bash: line 2: syntax error near unexpected token `(' bash: /tmp/conf.bash: line 2: ` ["foo"]=( "bar" "baz" )' bash: /tmp/conf.bash: line 3: syntax error near unexpected token `)' bash: /tmp/conf.bash: line 3: ` )'

But, if I make the file:

declare -A ASSOCIATIVE=(
    ["foo"]="bar baz"
 )

It works correctly:

borrajax@wharrgarbl:~# source /tmp/conf.bash
borrajax@hwharrgarbl:~# for key in "${!ASSOCIATIVE[@]}"; do \
                        echo "key: $key; values: ${ASSOCIATIVE[$key]}"; \
                        done
key: foo; values: bar baz

Is there a way of specifying that the values are arrays in a Bash script?

One possibility is set the values of the associative array as comma-separated strings and then split them into an array, but I thought maybe there's a way of formatting the bash file so that step is unnecessary.

I'm using Bash 4.2.28

Thank you in advance.

Answer 1

No. The values in an array (whether indexed or associative) can only be strings. It helps to think of bash arrays not as data structures, but a second level of quoting so that something like

args=("foo bar" "baz")
mycommand "${args[@]}"

passes two arguments, not three, to mycommand . In this scenario, nesting is not required, since a command can only take strings, not arrays, as arguments.