boot problems / redirection unexpected

[Zbigniew Szalbot]

hello,

Trying to boot 6.3. There seems to be some problem with /etc/rc.subr
it gives me some message about redirection unexpected. I am trying to
copy this file form a back-up to /etc but when I do that it says:
read-only file system.

I should add that I am operating as root (could not go into multiuser).

What are my options now? How do I make files in /etc writeable so that
I can copy the file from backup?

Many thanks!

Zbigniew Szalbot