Somehow I broke my JDownloader installation, I think by meddling with the network settings. Nothing would download, and the auto-update was borked. I decided to delete it and reinstall it, but I had quite a lot of download packages queued, and wanted to rescue them. I managed to do this successfully, here’s how:
Locate the “backup” folder, in JDownloader’s root directory. For me, as I used this method to install JDownloader, the folder was in “/opt/JDownloader/”. Find the most recent “backup.zip” file. Note that there may be some numbers between “backup” and “.zip”. In Ubuntu’s default file manager, Nautilus, one can select “List View” and then click “Date Modified” to easily find the most recent file.
Copy this file and paste it to your desktop.
Create a new folder on your Desktop, call it “BACKUP”. Copy all files in JDownloader’s root directory into this folder.
Follow these instructions to install JDownloader. You can skip the “sudo mkdir /opt/JDownloader” step if you installed JDownloader with this method.
When JDownloader is installed, extract the “backup.zip” file you copied to your Desktop and modify then execute the following in a terminal:
sudo mv ~/Desktop/database.script /opt/JDownloader/config/database.script sudo mv ~/Desktop/database.properties /opt/JDownloader/config/database.properties
Your packages should have been restored. If you’re happy with the new installation, you can go ahead and delete the “BACKUP” folder.