When you need to set a shell variable but don't want the contents displayed anywhere.

secret.sh

#!/usr/bin/env bash

set_secret() {
  local variable_name=$1
  if [[ -z "$variable_name" ]]; then
    read -r -p "Variable name: " variable_name
  fi

  read -s -r -p "Password: " variable_value
  declare -g "$variable_name"="$variable_value"
}