Word of warning, if you have chmod 0000 /bin/bash put it back to how you found it before running the update. If you didn't do this: cmd + s to boot in safe mod

Word of warning, if you have chmod 0000 /bin/bash put it back to how you found it before running the update. If you didn't do this: cmd + s to boot in safe mode. /sbin/mount -wu / and chmod bash back to a useable state, if you get stuck at log in.