When running the installer with output piped to a file (or otherwise not

writing to a terminal), the installer would accept all defaults for

prompts and then initiate the install. This may not be what people want.
We now require --noinput in order to do an unattended install. When

outputting to a non-terminal without passing --noinput, the installer

will exit with an error containing instructions.

Tested the results when piping to a file.
Tested default attended installs and unattended with --noinput.