MD5SUM value off by just one charecter

[steve7233]

I just built a new computer and download Kubuntu Trusty. When I loadded it into k3b it showed the following MD5SUM: aefdc97d26e54066f5b50d36c5d4218c. Your web site list the following:

aefdc97d26e51066f5b50d36c5d4218c kubuntu-14.04-desktop-amd64.iso Notice the 54066 instead of 51066. Yet k3b claims it matches. Is this a bug in k3bd? Should I use the file or re download the file?

[GreyGeek]

Personally I'd re-download it. As Askrieger once said:

It is NOT enough to verify the download, one bad byte in a music CD is totally unnoticeable, but one bad byte, in the wrong place, can ruin an installation CD.

So, after I burned a CD with a GOOD md5sum ISO I'd re-insert the CD and check it to make sure the burned CD was good as well.

From a previous thread on Kubuntuforums.net, the final version of the bash script as modified by BlindSide:

[FONT=courier new][B]dd if=/dev/cdrom bs=2048 count=$(( $(stat -c %s nameofisohere.iso) / 2048)) | md5sum[/B][/FONT]

$() : applies command substitution ie runs the enclosed command and uses the result in its place

stat -c %s "filename.iso" : grabs the filesize of "filename.iso" (in this case, the trusty tahr iso image)

$(( )) : applies arithmetic substitution, i.e. it evaluates the enclosed expression and uses the result in its place

Net upshot - the filesize is grabbed, divided by 2048 and plugged in as the 'count'

[Feathers McGraw]

Sounded like the kind of thing that could be a typo on the website, but I just downloaded and checked:

feathers-mcgraw@Hobbs-T440s:~/Downloads$ md5sum kubuntu-14.04-desktop-amd64.iso
aefdc97d26e51066f5b50d36c5d4218c  kubuntu-14.04-desktop-amd64.iso

...and the website is correct (also - kubuntuforums.net is privately owned, kubuntu.org is separate but "good friends" with KFN!)

Greygeek's advice about verifying the installation media is something you should definitely take on board - I was trying to install 14.04 to an old laptop and had a few failures, turns out it was the USB drive. If I had checked like GG suggests, I would have saved myself a lot of time!

Feathers

[jlittle]

Definitely weird; if you change one bit in a file, it's md5sum should change completely. It's very hard work to make a change to a file to cause a two-bit change in the md5sum, unless there's a glaring hole in MD5, which we'd know about. I almost suspect a hardware glitch, a cosmic ray maybe, but a display bug in k3b seems most likely.

Regards. John Little

[steve7233]

I re dowloaded it and it burned fine. I haven't tried installing it yet as the monitor is all red. Probably the graphics card isn't connecting to the mother board well enough.