cksum entire dir??
freebsd at edvax.de
Thu Sep 13 23:42:05 UTC 2012
On Wed, 12 Sep 2012 10:46:25 -0700, Gary Kline wrote:
> On Wed, Sep 12, 2012 at 07:31:45AM +0100, Matthew Seaman wrote:
> > On 12/09/2012 00:14, Polytropon wrote:
> > > % cksum <directory>
> > >
> > > and could obtain a checksum - so it _seems_ to work.
> > > After alteration of one file within the hierarchy a
> > > different result was printed.
> > That will give you a checksum on the directory inode -- file names and
> > associated metadata only, not file content. In theory you could edit a
> > file without modifying any of the timestamps, and that wouldn't result
> > in any change to the directory checksum. Also, modifying things a few
> > layers down the filesystem hierarchy won't have any effect either.
> > Generally I find the best test for differences between old and new
> > copies of a filesystem is 'rsync -avx -n ...'
> > Also, sum and cksum have way too small a key size for this to be
> > reliable, since you can't tell a true result from a hash collision. Use
> > md5 or sha1 or sha256 for best results.
> So this sha256 is *real*?? I have no md5 on my "fedora"
> that is on my desktop and m having trouble getting used to.
> but the gentleman who recommened cpio was right on the money.
> note that I am loathe to spam this list with the following mail from my
> files in sept, 1988, but here it is. if I had only gr -r -w cpio
> around in all my directories, I would have found this, sent to one Dirm
> Myers across the pond ::
> From kline Sat Sep 5 11:52:20 1998
> Subject: lost mail file...
> To: dirkm at buster.dhis.eu.org (Dirk Myers)
> Date: Sat, 5 Sep 1998 11:52:20 -0700 (PDT)
> Organization: <> thought.org: public access uNix in service... <>
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> Status: RO
> Yesterday morning I began composing the next two Q's and A's
> in my mailer. Last night in the wee hours there was a power
> glitch and I lost the mail.
> Enclosed is the first//next Q/A. I'll send along another one
> or two later today. One that I was playing around with *failed*
> and I'm trying to figure out why.
> How can I uise my FBSD floppy drive to copy files to it (in this case,
> at work), and retrieve the files on my FBSD systtem at home. So far
> I've only seen examples that used floppies with a filesystem on them.
> Is there a simplr, more direct way?
> You can treat the 'raw' floppy device as if it is a tape drive, and
> use typically UNIX tape tools to read/write, such as tar and cpio.
> For instance, to copy the current directory onto a floppy to
> take home at night:
> (put the floppy in the drive, and cd to the directory where
> the files are; then )
> % tar -cvf /dev/rfd0 .
> To read it when you get home:
> (put the floppy in the drive at home; and extract the tarball
> wherever you want the files)
> % tar -xvf /dev/rfd0
> The flags -c and -x indicate create and extract mode, the ``v''
> specifies verbose mode, and the ``f'' tells tar that the following
> argument is the file or device that tar acts upon. Here, it is
> the floppy devide.
> With cpio:
> (chdir to the directory where the files are)
> % ls | cpio -oc > /dev/rfd0
> To read a cpio archive from a tape drive:
> % cpio -icd < /dev/rfd0
> The flags -i and -o indicate copy-in or extract mode and
> copy-out or create archive mode. The ``c'' tells cpio
> to use the old, portablr ASCII archive format. And the
> ``d'' flag tells cpio to create directories where necessary.
> Do a
> % man cpio
> for much greater detail on this utility.
> There are another one or two of the simpler Q/A's and one or two
> more involved.
> Then, for this month only, I want to write a paragraph or two
> about who I am and where I'm coming from. Since you are sharing
> the by-line you might want to consider this too.
> PS: Next month we get a break!!
> Gary D. Kline kline at tao.thought.org Public service uNix
> as you can see, this dealt with my olden tape drive. a 250meg
> QIC drive, I think.
Really? I think /dev/rfd0 refers to fd - floppy disk. Even
though I know there are floppy-controller connected tape
drives (still have one myself!), the examples shown seem
to indicate work with a floppy disk, used in a "non-fs'ed"
manner, just as I did in the past with "tar, the most
universal file system that isn't even a filesystem" to
transfer files across different UNIX / BSD / Linux boxes
via floppy (because they've not been networked). Still the
examples look fully valid when applied to a tape drive, as
both floppy and tape can be (ab)used as "linear fs-less
> but this was about the earliest reference
> I could find re my use of cpio. there are others in my journal
> dir that reference my running out of hard drive and using cpio rather
> that a straight cp -rp.
I've been using cpio as a means of backup in combination
with a "chain" of 650 MB CD-R's.
Happy FreeBSD user since 4.0
Andra moi ennepe, Mousa, ...
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