Not for System-wide Backup
DejaDup is not the tool for system-wide backups. Backing up apps and system folders in Linux is tricky as one needs to preserve the ownership and permissions to make the system files work. If you want to have a backup of the system files and folders, it is best to boot it from a Live USB.
Many experienced Ubuntu users don't bother with system backups and just start with a fresh installation in a new computer. They may also keep a list of apps they have installed, and install them again after installing Ubuntu.
This is because Ubuntu (Linux in general) does not work like Windows. The OS and the installed apps have many files in common. This is called "dependency." If you install a newer version of Ubuntu in the new computer and try to restore an app that was backed up from an older version of Ubuntu in the old computer, the app probably won't work and the common files won't match.
DejaDup Backs Up Users' Data
By default DejaDup backs up an user's home folder and all its sub-folders when the user is logged in. That is. /home/aagam/
(Assuming "aagam" is your username).
If there is a second user of your computer, let's say the user "Begam", then that user's data in /home/begam/
is not backed up until Begam sets up the backup task.
Note, permissions are not defined by the username, but the UID (not to be confused with UUID), which is a number. For example, the user Aagam may have the UID 1000, and Begam may have the UID 1001 in the old computer. If the names and IDs are switched, in the new computer. For example, if Aagam has the UID 1001 and Begam has the UID 1000, then restoring the backup from the old computer to the new computer may give the permissions and ownership to the wrong person.
Configurations, Preferences, and Hidden Files/Folders
Ubuntu keeps the user specific settings, and encryption keys in the user's home folder. For example your ssh and gnupg (gpg) private keys are stored in the respective folders:
/home/aagam/.ssh/
/home/aagam/.gnupg/private-keys-v1.d/
Since these are sub-folders of your home folder /home/aagam/
they are all backed up when you set up DejaDup to backup your files.
Note the .
in front of the folders .ssh
and .gnupg
. That means these folders are hidden.
Hope this helps