On Mon, Feb 24, 2003 at 03:45:27PM -0800, Tim Howe wrote: > Doesn't cmp work? > > I ussually verify my OpenBSD boot floppies like so... > > $ cmp floppy33.fs /dev/fd0a > > Shouldn't this work for CDs and ISOs? > > --TimH I though so as well. If that were the case the isoinfo tool is not necessary and one could make a disk image like this: cp /dev/sr0 cdrom.img or cat /dev/sr0 > cdrom.img
However looking at the webpage it states: http://www.troubleshooters.com/linux/coasterless.htm#_Accurately_Reading_a_CD ... when you test your newly burned CD with md5sum, the data you read from /dev/cdrom must be accurate, or you'll get a false error alarm. Also, many CD's are burned off ISO images created from other CDs. If those original CD's were read incorrectly, then the resulting ISO's are incorrect, and every duplicate made from those ISO's is incorrect. Accurate CD reading is essential. Most bad CD device reads are caused by either: 1. Reading too few or two many blocks of the CD device 2. Inability to read the last block. This section explains how to consistently read the correct number of blocks. The only reliable method I've found to find the true end of the CD is with the isoinfo utility. -------- Cory > On Mon, 24 Feb 2003 08:57:04 -0800 (PST) > Dave Wyatt <[EMAIL PROTECTED]> wrote: > > > Google is your friend! > > I was going to post the question below, but found this > > on Google: > > > > http://www.troubleshooters.com/linux/coasterless.htm#rawread > > > > Any Comments? > > > > > > Short question: > > > > How can I verify or compare an ISO that I created from > > a known good CD? > > > > > > Long question: > > > > I created ISOs for Red Hat 8.0 from CDs I burnt from > > downloaded ISOs which checked good with the md5sums > > after downloading. After burning them, the CDs > > checked good with Red Hats checkmedia, so these are > > *my originals* that I wanted to make copies of for my > > son. I no longer have the downloaded ISOs. > > > > I did the > > > > dd if=/dev/cdrom of=RedHatDiskx.iso > > > > thing and created the ISOs. I then burned the CDs and > > began the checkmedia routine. CDs 1 and 2 passed and I > > wasn't going to check the rest but did anyway. CDs 3-5 > > failed checkmedia. I then re-checked the originals > > and they all passed checkmedia. So I ended up with 3 > > coasters, which isn't a > > > > big deal but pretty annoying. > > > > I looked at man dd and man md5sum. I don't see any > > way to verify with dd or to create md5sums from a data > > CD. Did I miss something? Is there a way to verify > > that an ISO created with dd is valid? Or that a CD > > burned from an ISO is good? > > > > BTW, if it makes any difference, the versions are: > > > > md5sum (textutils) 2.1 > > dd (fileutils) 4.1.11 > > > > on a SuSE 8.1 system. > > > > Dave > > > > > > __________________________________________________ > > Do you Yahoo!? > > Yahoo! Tax Center - forms, calculators, tips, more > > http://taxes.yahoo.com/ > > _______________________________________________ > > Eug-LUG mailing list > > [EMAIL PROTECTED] > > http://mailman.efn.org/cgi-bin/listinfo/eug-lug > _______________________________________________ > Eug-LUG mailing list > [EMAIL PROTECTED] > http://mailman.efn.org/cgi-bin/listinfo/eug-lug _______________________________________________ Eug-LUG mailing list [EMAIL PROTECTED] http://mailman.efn.org/cgi-bin/listinfo/eug-lug
