[hfs-user] How to use fsck_hfs on an unmounted medium?

Mark Day mday@apple.com
Fri, 11 Jun 2004 09:19:31 -0700

On Jun 11, 2004, at 8:38 AM, Pierre Duhem wrote:

> I use the df command to know which symbolic name to use when launching 
> the
> utility. Is there a way to know wich symbolic name to use when the
> volume is not mounted?

If you are on Mac OS X, you can use "diskutil list" to see the list of 
disks and partitions that Disk Arbitration knows about.  The problem 
disk may or may not show up in that list.  I don't know whether 
diskutil is part of Darwin.

I often just do a combination of "ls /dev/disk*" to see all the disk 
devices, and "mount" or "df" to see which of those are mounted.  Then 
it is a matter of guessing which of the unmounted disk devices is the 
right one.  It's usually easy to spot since none of the /dev/diskNsX 
devices will be mounted for some N.  The HFS volume is probably the one 
with the largest X.

> For instance, I have a HFS+ image, burned on a CD-ROM, which doesn't
> mount. The Disk Utility says that the node size is incorrect. I would
> like to check what fsck_hfs says indeed. However, since the unmounted
> CD-ROM is not listed by rge df command, which symbolic name should I
> use?

If you're using Disk Utility, then fsck_hfs isn't going to give you 
much more information.  The output you see in Disk Utility is actually 
coming from fsck_hfs (it execs fsck_hfs and displays the output in its 
window, formatted a bit differently).