Cfxtrjtrk

In a script I have an associative array like:

declare -A my_vars=( ["key1"]="value1" ["key2"]="value" )

Is there a single command to tranform that into a parameter list in the form

--key1=value1 --key2=value2

without having to manually re-write

 --key1="${VARS[key1]}" --key2="${VARS[key2]}"

the use-case I had in mind was to pass the array to a script as a list of parameters, like

my_script.sh $(to_param_list $VARS)

With a helper function:

#!/bin/bash



to_param_list () {

    declare -n outlist=$1

    declare -n inhash=$2



    for param in "${!inhash[@]}"; do

        outlist+=( "--$param=${inhash[$param]}" )

    done

}



declare -A my_vars=( ["key1"]="value1" ["key2"]="value" )



to_param_list list my_vars

my_script.sh "${list[@]}"

The final command in the above script would expand to the equivalent of having written

my_script.sh "--key2=value" "--key1=value1"

The to_param_list function takes the name of an array variable and the name of an associative array variable and uses these to create two "name reference" variables in the function (namerefs were introduced in bash release 4.3). These are then use to populate the given array variable with the keys and values in the appropriate format from the associative array.

The loop in the function iterates over "${!inhash[@]}", which is the list of individually quoted keys in your associative array.

Once the function call returns, the script would use the array to call your other script or command.

Running the above with

declare -A my_vars=( ["key1"]="hello world" ["key2"]="some thing" ["key3"]="* * *" )

and with printf 'Arg: %sn' being the command, the script would output

Arg: --key2=some thing

Arg: --key3=* * *

Arg: --key1=hello world

This shows that the options are generated without word splitting or filename globbing coming into effect. It also shows that the order of the keys may not be preserved since accessing the keys out of an associative array will do so in a fairly random order.

You can't really use a command substitution safely here as the result of it would be a single string. If unquoted, this string would then be split on whitespace characters (by default), which would additionally split both the keys and values of your associative array. The shell would also perform filename globbing on the resulting words. Double quoting the command substitution would not help as that would result in calling your my_script.sh with a single argument.