各位大神，我在开机前插上U盘，U盘能自动挂载。但是开机后拔下U盘再插上就不能自动挂载，但手动可以挂载，不知道是什么原因。以下是我相关文件的内容
rcS文件中挂载的相关内容：
echo -n " Mounting /proc : "
mount -n -t proc /proc /proc
status $? 1
echo -n " Mounting /sys : "
mount -n -t sysfs sysfs /sys
status $? 1
echo -n " Mounting /dev : "
mount -n -t tmpfs mdev /dev
status $? 1
echo -n " Mounting /dev/pts : "
mkdir /dev/pts
mount -t devpts devpts /dev/pts
status $? 1
echo -n " Enabling hot-plug : "
echo "/sbin/mdev" > /proc/sys/kernel/hotplug
status $? 0
echo -n " Populating /dev : "
mkdir /dev/input
mdev -s
status $? 0
fstab文件内容：
#device mount-point type options dump fsck order
proc /proc proc defaults 0 0
none /dev/pts devpts mode=0622 0 0
tmpfs /tmp tmpfs defaults 0 0
sysfs /sys sysfs defaults 0 0
mdev.conf文件内容：
sd[a-z][0-9] 0:0 666 @(/etc/hotplug/usb/udisk_insert $MDEV $SUBSYSTEM)
sd[a-z] 0:0 666 $(/etc/hotplug/usb/udisk_remove $MDEV $SUBSYSTEM)
ub[a-z][0-9] 0:0 666 @(/etc/hotplug/usb/udisk_insert $MDEV $SUBSYSTEM)
ub[a-z] 0:0 666 $(/etc/hotplug/usb/udisk_remove $MDEV $SUBSYSTEM)
audio 0:5 0666
console 0:5 0600
control.* 0:0 0660 @/bin/mv /dev/$MDEV /dev/snd/
dsp 0:5 0666
event.* 0:0 0600 @/bin/mv /dev/$MDEV /dev/input/
fb 0:5 0666
nfs 0:5 0770
null 0:0 0777
pcm.* 0:0 0660 @/bin/mv /dev/$MDEV /dev/snd/