Dynamically create array in bash with variables as array name

Question

This has been asked several times, but none of the methods work. I would like to dynamically create arrays with array names taken from the variables. So lets start with just one array for now:

#!/bin/bash i="aaa" eval ${i}=("1") 

results in

./1.sh: line 3: syntax error near unexpected token `(' ./1.sh: line 3: `eval ${i}=("1")' 

same result with:

$(eval ${i})=('1') $(eval echo ${i})=('1') $(eval "echo ${i}")=('1') 

I do not want to eval everything, justthe array name. If it is possible I would like to avoid using eval at all

Answer 1

eval expects a string as the argument. You can't use ( unquoted, it has a special meaning in shell.

i=aaa eval "$i=(1 2)" # Use a string, $i will expand in double quotes. echo ${aaa[1]} 

You can also use declare or typeset instead of eval:

declare -a $i='(1 2)' 

You still have to quote the parentheses and spaces.

To avoid eval completely, you can assign one by one:

#! /bin/bash name=aaa values=(1 2) for ((i=0; i<${#values[@]}; ++i)) ; do read "$name[$i]" <<< "${values[i]}" done echo ${aaa[1]} 

Answer 2

Here is a way to load the array without using eval. It doesn't use the ( data ) construct - instead it uses an input string with your choice of delimiter - the example uses |

i=aaa IFS='|' read -a "$i" <<<"1|2 with spaces" printf '%s\n' "${aaa[@]}" 

Output:

1 2 with spaces 

Answer 3

You can use declare with dynamic names and values, and variable indirection to reference variables based upon their name. printf '%q' can help you "shell-escape" values so that they can be used during dynamic assignments.

#!/bin/bash declare -a products=( phone computer ) printf 'Product: %s\n' "${products[@]}" # Product: phone # Product: computer unset products declare varName='products' declare -a "${varName}"='( cell\ phone laptop\ computer )' declare arrayRef="${varName}[@]" printf 'Product: %s\n' "${!arrayRef}" # Product: cell phone # Product: laptop computer unset "${varName}" declare -a toCopy=( 'LED TV' '"Smart" car' ) declare -a "${varName}"="( $( printf '%q ' "${toCopy[@]}" ) )" printf 'Product: %s\n' "${!arrayRef}" # Product: LED TV # Product: "Smart" car unset "${varName}"