How do you append to an indirect parameter expansion of an array in BASH?

Question

I know you can create an indirect parameter expansion to an array like so:

var1=\"target\"
var2=\"arrayname\"
targetarrayname=( \"one\" \"two\" \"three\" )
b         


        

Answer 1

With Bash 3.2 Compatibility

It avoids substantial security bugs to run all values through printf %q to ensure that they're safely escaped before substituting them into eval content.

#!/bin/bash

appendToArray() {
  local _targetArrayName _argumentData _cmd
  _targetArrayName=$1; shift || return
  printf -v _argumentData '%q ' "$@"
  printf -v _cmd '%q+=( %s )' "$_targetArrayName" "$_argumentData"
  eval "$_cmd"
}

target=( "first item" "second item" )
appendToArray target "third item" "fourth item"
declare -p target

...correctly emits as output:

declare -a target=([0]="first item" [1]="second item" [2]="third item" [3]="fourth item")

---

For Bash 4.3+ Only

#!/bin/bash

appendToArray() {
  declare -n _targetArray=$1; shift
  _targetArray+=( "$@" )
}

target=( "first item" "second item" )
appendToArray target "third item" "fourth item"
declare -p target

...has identical output, with much less (and much simpler) code.