How to dump a nullfs?

[Pietro Cerutti]

Hi List,
I use dump(8) as backup system, and I would like to dump only a
subtree of a filesystem, say /usr/local/etc, which is on the /usr
filesystem.

Since dump(8) only dumps filesystems, and not directories, I mounted
/usr/local/etc on /mnt/tmp, type nullfs:

$ mount
....
/dev/ad0s2e on /usr (ufs, local, soft-updates)
....
/usr/local/etc on /mnt/tmp (nullfs, local)
....

but I can't dump it:

$ dump -0 -u -a -f usr.local.etc /mnt/tmp
dump: /mnt/tmp: unknown file system

If I put an entry in fstab:

/usr/local/etc    /mnt/tmp             nullfs         rw,noauto   0  0

I mount it:
$ mount
....
/usr/local/etc on /mnt/tmp (nullfs, local)

and try to dump it, dump(8) crashes:

$ dump -0 -u -a -f usr.local.etc /mnt/tmp
  DUMP: SIGSEGV: ABORTING!
Segmentation fault (core dumped)


Any idea, workarounds or other ideas to dump only a directory are welcome!

Tnx, cheers!

--
Pietro Cerutti
<pietro.cerutti at gmail.com>

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