I got some help with this site (to find the jigdo package name, for example).
To download Debian ISO images or to update them, one needs the software, which is probably found in your repo’s under the name “jigdo-file.” You can read all about jigdo here and how it saves bandwidth for everybody and is the most efficient way of handling ISO downloads and updating (plus with Debian, you never need to get rid of your CD/DVDs and you can just update them, and you never have to reinstall your system … clearly Debian is superior in this respect). Instructions below:
So to install it, something along the lines of
aptitude install jigdo-file
from the root terminal (or use “sudo” before the line) will do the trick.
Then change your directory to whichever folder you want to download the updated iso image in. Example: “cd /home/yourName/Downloads”. If you don’t do anything, you will probably end up with the file in your home directory, which is fine, too. To run jigdo from terminal (don’t do this as root), simply type “jigdo-lite”. Once you’re running jigdo-lite, you will be prompted to type the URL of the mirror that you want. Type in whichever one you want from the debian.org site. An example for 64-bit Debian testing is “http://cdimage.debian.org/cdimage/weekly-builds/amd64/jigdo-dvd/debian-testing-amd64-DVD-1.jigdo”.
Then you will be asked to mount an existing ISO image if you have one. If you don’t, just skip by pressing enter. If you do (and you should, as this will save you a lot of time and your server a lot of bandwidth), you should enter the filepath to your ISO image. Now if you have your ISO on a CD, simply find the path to your CD. It is probably either something like “/mnt/cdrom” or “/media/cdrom0”. Or if you want, you can point to a mounted iso image directory from your file system (and skip the CD/removable media altogether). For a howto, see this post.
Then to specify the appropriate mirror, type in something like the following:
You can also find the list of Debian mirrors here. That should be it. You can let the program run in the background as you grab a coffee or read more posts in my blog. 🙂 Anyway, if anything pops up, the instructions within the program should be clear enough. Any questions? Things I missed? Feel free to comment below.