Hi all,

Firstly, is an .img 'raw image' file the same as an .iso 'disk image' file? I mean, exactly the same format but for the different file extensions? Some googling I've done would seem to indicate so, but I've not found anything definitive and more often than not, the combination of "raw" and "image" entered into a search engine just throws up a lot of stuff about digital photography.

Secondly, in the belief that the two file types are identical, I've tried making a USB rescue stick by copying an .iso image file over to it using programs like All Image and Self Image, but the resulting stick isn't bootable and Linux just sees it as a CD rom device, placing a CD icon on the desktop. What am I doing wrong??

TIA,

CC.

There is a very useful site that explains just about every known extension. Here it is pointing at the .img extension You can then type in .iso and you'll see the difference.
http://filext.com/file-extension/IMG
Google is your friend.
cheers
jdk

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Moved: This thread is more suitable in Linux-Newbie and has been moved accordingly to help your thread/question get the exposure it deserves.

You cannot take a dvd.iso and just burn it to a usb stick and expect it to work. Just like you cannot put the DVD.iso on a HD or FD and just boot to it. Each type of media has a different area that they look at for boot information. If you look on the wiki of most distros they now have instructions on how to make a bootable usb/flash stick.

That's exactly the info I was hoping for and expecting to make sense out of this, thanks!
CC.

you would need 'syslinux' to do this, depending on your distribution you are using to create your bootable thumbdrive it might already be installed

a good start would be to take a knopix iso
mount it with mount -o loop knoppix.iso /mnt/knoppix (first create the directory /mnt/knoppix)
then mount your thumbdrive to say /mnt/thumbdrive

copy the contents of the knoppix iso to the thumbdrive (cp -rv /mnt/knoppix /mnt/thumbdrive)
rename the isolinux.cfg file to syslinux.iso
unmount the thumberive

as root (using su or sudo) run syslinux /dev/sda (where /dev/sda is the device node for your thumbdrive
also make sure to fdisk (again as root) your thumbdrive and set the partition to bootable
reboot your computer and make sure you tell it to boot from the thumbdrive and see if it works

A .img file could be simply be an image of a partition. (short for image)
One way to find out is using the file command.

file sample.img

This will tell you if it detects an iso9660 filesystem (cd and datadvd); a UDF filesystem image (Video DVDs); or a bootable filesystem.

You can't rely on what the extension is. The file may have been misnamed or the extension may have a number of uses.

good advice , in my case a *.img( or .imq) is normally a photo from a spacecraft on The Planetary Data System .