No Prompt & Password Fill Install for Homebrew
The -s option is working for me, so I don't know why it doesn't work for you.

Have you tried to add #!/bin/sh (or #!/bin/bash) in the top of your script ??

If you use the -n option on echo you'll get the input on the same line as the label. 

So the below is having the input: Password: &lt;waiting for input&gt;, and on the next line it just print the password entered - the awk is just for testing that the pipe was working. And then I've added a loop so that something always need to be entered.

#!/bin/sh

readPassword
echo $PASSWORD | awk '{print $1}'

readPassword() {
   echo -n "Password: "
   read -s PASSWORD
   echo ""
   if [[ -z "$PASSWORD" ]]; then
      printf '%s\n' "A password is required..."
      readPassword
   fi
}