How to upgrade Image by jigdo

mount your debian iso image to /mnt/cdrom cypress@debian8:~/Lab/Test1$ sudo mount -o loop ./debian-8.2.0-amd64-DVD-1.iso /mnt/cdrom/ mount: /dev/loop0 is write-protected, mounting read-only user jigdo-lite cypress@debian8:~/Lab/Test1$ jigdo-bin-0.7.3/jigdo-lite ./debian-update-8.7.1-amd64-DVD-1.jigdo

3.

If you already have a previous version of the CD you are downloading, jigdo can re-use files on the old CD that are also present in the new image, and you do not need to download them again. Mount the old CD ROM and enter the path it is mounted under (e.g. `/mnt/cdrom'). Alternatively, just press enter if you want to start downloading the remaining files. You can also enter a single digit from the list below to select the respective entry for scanning: 1: /mnt/cdrom Files to scan: /mnt/cdrom type enter and chose mirror to download

link https://ftp.sjtu.edu.cn/Linux-HOWTO/HOWTO/html_single/Debian-Jigdo/