avine
Posts: 2
Joined: Tue Jun 19, 2012 4:21 pm

Downloading Image File

Tue Jun 19, 2012 5:12 pm

I am a beginner. As a general comment I do not find the "beginners' section of the forum" user friendly. To my mind some very very basic turorials are required for those of us that are less experienced.

I am using a windows 7 machine and am trying to download an image file to load on to an SD card. Following the Wiki instructions (which seem the most useful source of information), I am directed to the Raspberry Pi downloads page (http://www.raspberrypi.org/downloads). I decide to go for the "Debian Squeeze version" and use the link for a direct download as I have never heard of "Torrent"

[As an aside I cannot find any instructions on how to excecute a torrent download on a Windows machine. As I am on a learning expedition can someone point me in the right direction?]

The link to the download page works and Firefox tells me debian6-19-04-2012 is ready for download. I select an save location and a compressed folder duly arrives. So far so good. In Explorer I right click on the folder and using WinZip, extract to the same location. This creates a new folder "debian6-19-04-2012" which contains two files. The first "debian6-19-04-2012" is 1,904,297 bytes in length and I imagine is the image file I am after, notwithstanding that it has a "WinZip File" type in the Explorer listing. I also have a small 1KB SHA1 file. No mention anywhere as to what this might be.

However, following the instructions on the Raspberry Pi Distribution Downloads page I attempt to "verify the image with the SHA-1 checksum provided above". It fails to verify but I note that the resulting checksum corresponds with that contained in the SHA1 file extracted along with the supposed image. Am I right in assuming that this means that my supposed image is indeed that and is valid?

If so and the RPi staff monitor these forums an amendment to their Distribution Downloads page would appear to be in order.

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penguintutor
Posts: 376
Joined: Tue May 08, 2012 9:11 am
Location: UK
Contact: Website

Re: Downloading Image File

Tue Jun 19, 2012 8:17 pm

If you don't know what a Torrent is then you can ignore it and use the normal download, but here's an explanation.

BitTorrent

BitTorrent is a peer-to-peer file sharing protocol. Torrent is the name of the file you download to start the download process working.

BitTorrent has a bit of a bad reputation as people sometimes use it for downloading copyrighted files (DVDs etc), but the tool has a legitimate use and is a great way of downloading Linux images as it reduces traffic to the main servers, and is usually much faster. Most Linux distributions come with a Torrent client (although the Pi Debian Image doesn't have one installed by default), but for Windows you'll need to download one - see: http://en.wikipedia.org/wiki/Comparison ... nt_clients.

Checksum

As far as the Checksum I believe you are entering the checksum for the zip file rather than for the ISO image. If you download the file and then run the SHA checksum against the zip file and compare with the checksum on the website then it should confirm that the file has downloaded correctly.

If you unzip the file before testing the checksum then the SHA file is for the iso file.

You shouldn't need to use both checksums. The one in the zip file is usually provided so you can verify the file has downloaded correctly. The one on the website is however more secure to prevent against someone inserting malicious code, as it means that anyone trying to introduce malicious code into the distribution would also need to update the website with the new checksum.

The most common cause of a failed checksum is if a download is interrupted, but that would normally result in not being able to open the file anyway.

Joe Schmoe
Posts: 4277
Joined: Sun Jan 15, 2012 1:11 pm

Re: Downloading Image File

Tue Jun 19, 2012 8:41 pm

ISO file???
And some folks need to stop being fanboys and see the forest behind the trees.

(One of the best lines I've seen on this board lately)

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penguintutor
Posts: 376
Joined: Tue May 08, 2012 9:11 am
Location: UK
Contact: Website

Re: Downloading Image File

Wed Jun 20, 2012 9:20 am

Sorry - I meant to say img file instead of iso file.

avine
Posts: 2
Joined: Tue Jun 19, 2012 4:21 pm

Re: Downloading Image File

Tue Jun 26, 2012 11:04 am

Many thanks, that is really helpful.

bbncomms
Posts: 16
Joined: Tue Jun 26, 2012 2:43 pm

Re: Downloading Image File

Tue Jun 26, 2012 3:54 pm

If in Windows you cannot see a file type eg.img, then the chances are that your PC is in the default mode where 'hide extensions from known file types'
If you go to Control Panel and select Folder Options, have a look under the View tab and selections within the Advance settings window.
Whenever I get a 'new' pc/installation this is one of the 1st places I go to make things easy for me - that way I can see hidden files etc. etc.

Whether this is why your checksum fails no idea. I have been doing this with success on a number of similar downloads. Remenber that the checksum is supposed to relate to the zipped/compressed file.
Am using sha1sum.exe in W7 64 bit.

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