[sf-lug] (no subject)

Rick Moen rick at linuxmafia.com
Sun Jul 23 19:20:25 PDT 2006

Quoting ron (rondosxx at yahoo.com):

> Here's a url for a how-to on downloading isos:
> https://help.ubuntu.com/community/BurningIsoHowto

You'll notice that the Ubuntu and Kubuntu instructions say nothing about
what actual _programs_ you're using, when you follow their UI
instructions that are couched strictly in terms of GNOME and KDE menus
(respectively).  Which means they'll probably work on identically
laid-out Linux desktop systems, but will be utterly useless on anything
even slightly different.  (On the plus side, explanations are kept
simple or at least _seemingly_ simple.)

Just for collective understanding, the Linux programs you end up using to
perform CD burns, when you follow those instructions, are k3b (reached
via Konqueror acting as a file browser) and GnomeBaker (reached via
the Nautilus file browser).  

k3b in particular has lots of admiring fans.  It's said to be a bit
similar-looking to some popular MS-Windows CD-burning program that I've
never seen, maybe "Nero", but to be easier to use.  It's open source.

Both programs (k3b and GnomeBaker) are examples of a category of apps
that also includes dozens of other candidates:  Graphical front-end
programs that use the "cdrecord" command-line program (among other
things) to performs its tasks.

cdrecord's a little peculiar (in part because its author, Jörg Schilling, 
doesn't like Linux and uses a deliberately peculiar way of specifying
which device is your CD burner), but it's not bad.  Last I heard, you
still had to run it as root, and here's some typical syntax:

# cdrecord -v -dev=1,0,0 -eject somename.iso
            ^     ^        ^    ^
            |     |        |    |-----------Name of image file to burn from
            |     |        |----------------Eject when you're done.
            |     |-------------------------Which device your burner is, 
            |                               using Schilling's odd syntax.
            |                               "cdrecord -scanbus" finds it.
            |-------------------------------Verbose output.

Schilling also decided to be a dick about DVD-burning support, refusing
to add it to the open-source cdrecord code, but rather restricting it to
a proprietary "Cdrecord Pro" variant -- but it wasn't a difficult coding 
problem, which is why numerous cdrecord-variants have sprung up with DVD 
support, including "dvdrecord", among others.

It was beastly hot -- about 40 degrees C or so at the worst point -- at
yesterday's CABAL meeting (a little better today), and as usual I was
kept very busy running arond cleaning dishes, etc., so I was probably
the most heat-affected in the entire group.  Ron asked me "How do you
copy CDs in Linux?"  Partly because I was boiling over, I didn't realise 
Ron could be asking about either of two separate things:

o  How do you burn a physical CD, given an ISO (more precisely,
   "ISO9660") file?
o  How do you create an ISO file, given a physical CD?

Something like cdrecord is necessary for the former operation because
burning CDs/DVDs is timing-sensitive:  The burn runs at a constant speed
and cannot slow down to wait for reading of fresh input data:  If the
input buffer "underflows", you get a ruined disk.  Therefore, programs
like cdrecord create and manage big memory buffers, and inform you if,
despite their efforts, the buffer ran dry during the burn session.

The second operation -- making a disk-image file from a physical disk -- 
is _not_ timing sensitive.  Therefore, you can do it with about the
simplest, smallest tool imaginable, "dd".

Nobody remembers, any more, what the name stands for (see:
http://en.wikipedia.org/wiki/Dd_(Unix) ), but I think of it as
"disk-to-disk".  In essence, it's a dirt-simple bit copier.  Its basic
syntax is:

# dd if=[some device or file]  of=[some device or file]
       ^                         ^
       |                         |--- output file
       |----------------------------- input file

So, if you have placed the first CentOS 4.3 disk for i386 into your CD
drive and know that that drive is /dev/hdc, then this will create an
image file of it inside your current directory:

# dd if=/dev/hdc of=Centos-4.3-disk1-i386.iso

I haven't played around with many of the graphical front-end programs
like k3b (I just use dd, cdrecord, and once in a blue moon mkisofs to 
"master" a CD image from a directory tree), but believe most or all of
them can manage the process of making an image file from a physical
disk (as well as of mastering such images from file trees, and of
burning physical CDs from image files).

You may find interesting the stuff I have at 
"DVD" and "DVD Burning" on http://linuxmafia.com/kb/Hardware .

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