title: Double curly braces in Bash - bad substitution
body: <p>This works:</p>
  <p><code>echo ${!var_pointing_to_another_var}</code></p>
  <p>This doesn't:</p>
  <p><code>echo ${!${var}_string_suffix}</code></p>
  <p>In other words, I have a variable consisting of two parts: the first part is another variable, the second part is a string suffix. Together, they form a variable that would point to another variable. But I get a bad substitution error.</p>
  <p>Due to readability and security issues, I want to avoid the <code>eval</code> command.</p>