How to quickly determine if UFS2 FS is "clean" from command line?

David Wolfskill david at
Thu Dec 25 17:49:56 PST 2008

On Fri, Dec 26, 2008 at 01:22:24AM +0000, Bruce Cran wrote:
> ...
> > Anyone know of a reasonable way to quickly determine whether or not
> > a UFS2 file system is clean from the command line?
> dumpfs will tell you the status of the 'clean' flag:
> dumpfs /dev/ad0s1d | grep clean
> That will output a line like:
> cgrotor 0  fmod 0  ronly 0  clean 1
> Just like with fsck you can also tell dumpfs the previous mountpoint
> too and it'll use the right device.

So this is quite useful.

A reality check later, I find that for the file systems in question,
dumpfs(8) produces the wanted information (and quite a bit more) nearly
instantly, then spends about 33 seconds dumping cylinder group
information that I have no interest in.

While I admitted not being much of a C coder, I have been known to hack
a bit.... :-}

I also see that the dumpfs(8) code has been fairly static in the last
couple of years.

Would anyone else be interested in a hack to dumpfs(8) in the form
of a command line flag (e.g., "-s" -- as in "short" or "super block
only") to tell it to just spit out the FS super block information
and skip the cylinder group stuff?  (The command presently has but one
command line flag;  it is "-m" and is optional; if present, it causes
the program to spit out a newfs(8) invocation to re-create the file
system in question.)

I'd be willing to cobble it up, test it, and submit a PR....

David H. Wolfskill				david at
Depriving a girl or boy of an opportunity for education is evil.

See for my public key.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 195 bytes
Desc: not available
Url :

More information about the freebsd-hackers mailing list