我的fstab如下：
# See the fstab(5) manual page for important information on automatic mounts
# of network filesystems before modifying this file.
#
# Device Mountpoint FStype Options Dump Pass#
/dev/ad0s3b none swap sw 0 0
/dev/ad0s3a / ufs rw 1 1
/dev/ad0s3e /home ufs rw 2 2
/dev/acd0c /cdrom cd9660 ro,noauto 0 0
proc /proc procfs rw 0 0
/dev/ad0s1 /mnt/winc msdos ro 0 0
/dev/ad0s5 /mnt/wind msdos ro 0 0
/dev/ad0s6 /mnt/wine msdos rw 0 0
cd /cdrom,ls没有任何东东。
# cd /cdrom
# ls
# umount /dev/acd0c
umount: /dev/acd0c: not currently mounted
# mount -t cd9660 /dev/acd0c /cdrom
cd9660: /dev/acd0c: Input/output error
#