Is there anyway of performing a media check of an install DVD without actually booting off it? That is, I've just burned a DVD and would like to be able to check it now rather than during the install (to reduce downtime on the machine I'm installing onto).
Danny. --------------------------------------------------------- http://dannyreviews.com/ - over nine hundred book reviews http://danny.oz.au/ - civil liberties, travel tales, blog ---------------------------------------------------------
On Tue, 2007-01-02 at 12:58 +1100, Danny Yee wrote:
Is there anyway of performing a media check of an install DVD without actually booting off it? That is, I've just burned a DVD and would like to be able to check it now rather than during the install (to reduce downtime on the machine I'm installing onto).
Each ISOs directory contains a file called SHA1SUM that contains the SHA-1 hashes of the images. You can use a tool called sha1sum to calculate this hash from the image and compare it to the content of the SHA1SUM file.
If the filename in the SHA1SUM file matches that of the image on your hard disk (and they are in the same directory), then run the following in that directory: $ sha1sum -c SHA1SUM
Otherwise, you'll have to manually check the hash against the file contents: $ sha1sum image-name.iso
(Note that these calculations will be very time-, disk- and processor-intensive. It takes just bit more than full minute of peak usage on my 2.4GHz Pentium 4 to calculate the hash of the FC6/i386 DVD image.)
Peter Gordon wrote:
Each ISOs directory contains a file called SHA1SUM that contains the SHA-1 hashes of the images. You can use a tool called sha1sum to calculate this hash from the image and compare it to the content of the SHA1SUM file.
I wanted to check the burn, not the download. But your message gave me half what I wanted.
I ended up doing the following
* looked at how big the iso image was and divided that by 512 to get the number of blocks in it * dd if=/dev/dvd of=check.iso count=blocks * sha1sum check.iso * compared that with the SHA1SUM file
Danny. --------------------------------------------------------- http://dannyreviews.com/ - over nine hundred book reviews http://danny.oz.au/ - civil liberties, travel tales, blog ---------------------------------------------------------
On Tue, Jan 02, 2007 at 01:17:24PM +1100, Danny Yee wrote:
Peter Gordon wrote:
Each ISOs directory contains a file called SHA1SUM that contains the SHA-1 hashes of the images. You can use a tool called sha1sum to calculate this hash from the image and compare it to the content of the SHA1SUM file.
I wanted to check the burn, not the download. But your message gave me half what I wanted.
I ended up doing the following
- looked at how big the iso image was and divided that by 512 to get the number of blocks in it
- dd if=/dev/dvd of=check.iso count=blocks
- sha1sum check.iso
- compared that with the SHA1SUM file
"sha1sum /dev/dvd" would have saved you a step. In Unix or Linux, everything is a file. Everything.
Of course, if the downloaded image is broken, it (and any DVDs) are useless, so the first step is to check the image:
sha1sum -c SHA1SUM
(assuming you have the SHA1SUM file handy.)
At 7:38 PM -0700 1/1/07, Charles Curley wrote:
Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="BghK6+krpKHjj+jk" Content-Disposition: inline
On Tue, Jan 02, 2007 at 01:17:24PM +1100, Danny Yee wrote:
Peter Gordon wrote:
Each ISOs directory contains a file called SHA1SUM that contains the SHA-1 hashes of the images. You can use a tool called sha1sum to calculate this hash from the image and compare it to the content of the SHA1SUM file.
I wanted to check the burn, not the download. But your message gave me half what I wanted.
I ended up doing the following
- looked at how big the iso image was and divided that by 512 to get the number of blocks in it
- dd if=/dev/dvd of=check.iso count=blocks
- sha1sum check.iso
- compared that with the SHA1SUM file
"sha1sum /dev/dvd" would have saved you a step. In Unix or Linux, everything is a file. Everything.
...
This gives a different checksum than the command below, which gives the correct checksum. Checking extra 0's at the end of the DVD changes the sum.
[]# dd if=/dev/dvd bs=2048 count=`isosize -d 2048 /dev/dvd` | sha1sum
AIUI, even this can fail due to the kernel readahead bug. Sometimes it is necessary to read the ISO into a file and trim it to the correct size. See Paul Howarth's isograb script at http://www.city-fan.org/tips/IsoImageFromMedia.
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Charles Curley -
Danny Yee -
Peter Gordon -
Tony Nelson