I'm on Nexus S, 2.3.4, stock and rooted. BusyBox is v1.18.4 (2011-03-20 15:16:04 CDT). When I try to remount ANYTHING it just

$ mount -o remount,rw /system
Usage: mount [-r] [-w] [-o options] [-t type] device directory

Any ideas how to fix that? Is it a BusyBox issue?

2 Answers 2


You are not specifying the device to mount, only the directory so it is telling you that you are missing one of the required parameters.

I believe that the busybox mount will let you get away with not supplying the device, if it can figure out the device to mount, but the "stock" mount requires that you supply both the directory and the device.

you would have to do the following:

# mount -o remount,rw /dev/block/mtdblock4 /system

or you could try the busybox mount

# busybox mount -o remount,rw /system

but you should always supply the device to mount, so there is no confusion or issue with mounting the wrong device.

  • busybox mount -o remount,rw /system did the trick.
    – bot47
    Jun 21, 2011 at 14:00

You may have root, but that is not a root shell (as evidenced by the $ prompt). You need to use su to switch to root before you can use mount. Since the default target is the root UID, you can simply enter su and it should properly switch to root (a # prompt). I think the reason it's failing is simply because you're running it as an underprivileged user.

  • Same with # mount -o remount,rw /system
    – bot47
    Jun 21, 2011 at 13:35
  • @bot47: Strangely that works for me, but I suppose the other test would be to specify a device. E.g. something like mount -o remount,rw /dev/block/mtdblock4 /system where /dev/block/mtdblock4 is the partition where /system lives (I think Nexus S is mtdblock3 but you can check with just mount by itself). Jun 21, 2011 at 13:38

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