How to cat multiple files from a list of files in Bash?

Question

I have a text file that holds a list of files. I want to cat their contents together. What is the best way to do this? I was doing something like this but it

Answer 1

#!/bin/bash

files=()
while read; do
    case "$REPLY" in
        \#*|'') continue;;
        *) files+=( "$REPLY" );;
    esac
done < input
cat "${files[@]}"

What's better about this approach is that:

1. The only external command, cat, only gets executed once.
2. It's pretty careful to maintain significant whitespace for any given line/filename.