Jigsaw Download, or short jigdo, is a scheme developed primarily to make it easy to distribute huge filesystem images (e.g. CD (ISO9660) or DVD (UDF) images) over the internet, but it could also be used for other data which is awkward to handle due to its size, like audio/video files or large software packages. jigdo tries to ensure that the large file (always called image from now on) is downloaded in small parts which can be stored on different servers. People who want to download the image do so by telling the jigdo(1) (NOT IMPLEMENTED YET) download tool to process one `.jigdo\' file; using it, jigdo downloads the parts and reassembles the image. jigdo-file is used to prepare the files for download. What makes jigdo special is that the parts that are used to reconstruct the image can have any size and content - they only need to be contained in a contiguous region anywhere in the image.For example, if you wish to distribute an ISO9660 image which contains a snapshot of an FTP server, you can instruct jigdo-file to prepare the download data in such a way that when people use jigdo to download the image, jigdo actually fetches the individual files from the FTP server and assembles them into an exact copy of your image - during the download! (If the image is not a filesystem dump, you can use split(1) to create the small parts that the image will be reassembled from.)
