How the heck can that happen?
To be honest guys, I'm not an expert on that subject. But to share my experience with you, there are (very few actually) occasions that after downloading a ISO (say an operating system) and then after burning it to a CD/DVD but while trying to boot into the OS, the CD/DVD rom says "corrupted disk" or something similar ("bugger!" errrr).
To make things worse, while burning CD/DVD in this case, the application wasn't able to detect any "corruptions" and as result now I have an entire CD/DVD wasted!. But if I used a checksum calculator before burning it into a CD or DVD then the app most probably be able to detect the "corruption".
|GtkHash main window...|
The reason I said "maybe" was because, sometimes these corruptions occur in a very very subtle ways thus it may not even be visible which only gives errors while trying to use it. But there are occasions however not only Checksum apps can let you identify corrupted files but they can even recover some of the damaged data too!.
Although not just while downloading these corruptions can occur while you're simply copying a file in between your local HDD or USB, etc.
I think the reason for such behavior is due to the fact that when copying or downloading, etc the OS first sends the data to the cached location on RAM and then to the HDD... thus in the process some of the data can be corrupted due to small voltage fluctuations on RAM, due to data collisions, or common data losses while downloading etc (scary stuff huh ;-) ). Whatever the reasons are, they can happen.
In thas sense, GtkHash is actually does not let you check for the integrity but it's a handy application that lets you calculate or create a Checksum for any given file and save it, thus say the data on that file is very very sensitive (perhaps it contains passwords or bank account numbers, etc).
Then after you moved/copied the file into a disk or any location that you want then you can later use a Checksum (also known as integrity check) checker to make sure whether it's corrupted or not.
Because for a password or especially for archives and encrypted data, even the most subtlest "data corruption" can make it un-usable!. CD/DVD burning applications usually come with a built in ability to check the integrity via Checksums generated by apps such as GtkHash.
|It supports creating Checksums using various algorithms...|
In that sense, GtkHash is a GTK written (obviously :D) Checksum generator that you can use to create a Checksum file for any given file under GNU/Linux using various algorithms.
You can install GtkHash in Ubuntu 11.04 Natty Narwhal, 10.10 and 10.04 by using the below command in the Command-line window.
sudo apt-get install gtkhash
|It has a separate "list view" that lets managing multiple files with ease ...|