Jigdo

Jigdo (a portmanteau of "Jigsaw" and "download") is a utility typically used for downloading to piece together a large file, most commonly an optical disk image such as a CD, DVD or Blu-ray Disc (BD) image, from many smaller individual constituent files. The constituent files may be local and/or retrieved from one or more mirror sites. Jigdo's features are similar to BitTorrent, but unlike BitTorrent, Jigdo uses a client-server model, not peer-to-peer.

Jigdo itself is quite portable and is available for many UNIX and Unix-like operating systems, and is also available for Microsoft Windows.

Released under the terms of the GNU General Public License, Jigdo is free software.

Uses

A quite common use would be to construct a Linux CD or DVD image for installation or distribution, where a slightly older version or release of same, or a cache or local partial mirror, already contains some or many of the needed constituent files. That would typically proceed as follows: Jigdo would typically be invoked using the jigdo-lite command, with a command line argument of the URL of a ".jigdo" file. Jigdo would then download that file, and after examining its contents, would generally also download a ".template" file. After inspecting the ".template" file, Jigdo would generally prompt for location of files to scan. The user would then generally enter (or select from list) location of files to scan, and Jigdo would scan that location for any files that may match any of the needed constituent files, and Jigdo would then use any such needed files found in constructing the target image. Jigdo likewise prompts again, and if the user gives a location, the process repeats - giving Jigdo opportunity to scan multiple locations for needed files. If the user enters no location, Jigdo then proceeds to download any still needed constituent files, and to then assemble the target image file.