in a Vagrantfile, I define a local variable. How can pass it to a bash script as a parameter? $var, #var, #{var}?

In a Vagrantfile, I want to run scripts.
But some part of them shouldn't run in provision mode.

I've sat a local variable update = "true" (or false) depending of the value of the Vagrant command.

A puts shows me that it is valued by "false", by example,
but then, I'm unable to send its content to a bash script, for parameter.

I've tried $update, #update, #{update}, update without success
on the line bash common/300_Kafka.sh "3.4.0" "2.12" $update

Part of the Vagrantfile:

if ARGV[0] == "provision"
  update = "true"
else
  update = "false"
end

puts "Vagrant box. Démarrage en mode mise à jour : " + update

config.vm.provision "file", source: "../common", destination: "common"

config.vm.provision "shell", privileged: false, inline: <<-SHELL
  bash common/050_Certificats.sh
  bash common/070_Utilitaires.sh
  bash common/100_JDK.sh "17"
  bash common/150_Postgresql-Postgis.sh "15" "3" "postgres"
  bash common/200_NodeJS-Angular.sh "16"
  bash common/250_ELK.sh "7.x"
  bash common/300_Kafka.sh "3.4.0" "2.12" $update
SHELL

Message on console:

Vagrant box. Démarrage en mode mise à jour : false

default: Indiquez si Kafka est en installation initiale (false) ou update (true).  n'est pas accepté.

The bash script called, testing the values:

#!/bin/bash
# $1: Version de Kafka [3.4.0]
# $2: Version de Scala associée [2.12]
# $3: Mode update (true) ou installation initiale (false)
echo "300 : Installation de Kafka $1 basé sur Scala $2"
export DEBIAN_FRONTEND=noninteractive

if [ -z "$1" ]; then
  echo "Précisez la version de Kafka à installer. [Recommandée : 3.4.0]" >&2;
  exit 1;
fi

if [ -z "$2" ]; then
  echo "Précisez la version de Scala liée. [Recommandée : 2.12]" >&2;
  exit 1;
fi

if [ "$3" != "true" ] && [ "$3" != "false" ]; then
  echo "Indiquez si Kafka est en installation initiale (false) ou update (true). $3 n'est pas accepté." >&2;
  exit 1;
fi

update=$3

if [ "$update" == "false" ]; then
   cd /tmp && wget -q "https://downloads.apache.org/kafka/$1/kafka_$2-$1.tgz"
   sudo tar -xf "kafka_$2-$1.tgz" -C /opt
   echo "export KAFKA_HOME=/opt/kafka_$2-$1" >> ~/.profile
else
   echo "En mode update, Kafka ne se réinstallera pas."
fi

My way of sending parameters to shell script isn't correct.
It looks working but doesn't perfectly, inside of an inline <<-SHELL.

I found myself successful with that, instead:

if ARGV[0] == "provision"
  update = "true"
else
  update = "false"
end

puts "Vagrant box. Démarrage en mode mise à jour : " + update

config.vm.provision "file", source: "../common", destination: "common"

config.vm.provision "shell", privileged: false, path: "../common/050_Certificats.sh"
config.vm.provision "shell", privileged: false, path: "../common/070_Utilitaires.sh"
config.vm.provision "shell", privileged: false, path: "../common/100_JDK.sh", args: ["17"]
config.vm.provision "shell", privileged: false, path: "../common/150_Postgresql-Postgis.sh", args: ["15", "3", "postgres"]
config.vm.provision "shell", privileged: false, path: "../common/200_NodeJS-Angular.sh", args: ["16"]
config.vm.provision "shell", privileged: false, path: "../common/250_ELK.sh", args: ["7.x"]
config.vm.provision "shell", privileged: false, path: "../common/300_Kafka.sh", args: ["3.4.0", "2.12", "#{update}"]

I would try

bash common/300_Kafka.sh "3.4.0" "2.12" "#{update}"

because from the error message it seems like it explicitly expects the string "true" or "false".