FreeBSD: fix error in rc.conf in recovery shell

filesystem is mounted readonly … how to remount and repair rc.conf

/etc/rc.conf: 17: Syntax error: Unterminated quoted string
Enter full pathname of shell or RETURN for /bin/sh:
# fsck
# mount -u /
# mount -a -t ufs

if you got a wired keyboard layout and cant find the / (slash)

# fsck
# pwd
# /
# mount -u $(pwd)
# mount -a -t ufs