What is indirect expansion? What does ${!var*} mean?

Question

I\'m reading \"Bash Guide for Beginners\". It says:

If the first character of PARAMETER is an exclamation point, Bash uses the

Answer 1

You can refer to this GNU doc for bash for authoritative information

https://www.gnu.org/software/bash/manual/html_node/Shell-Parameter-Expansion.html#Shell-Parameter-Expansion

But basically, indirect expansion is not performed on ${!prefix*} as one of the exceptions, in your example, N is the prefix.

The Document will explain what indirect expansion is in bash