I wanted to backup
/var/cache/apt/archives using 'Deja Dup' but it keeps saying >>
Could not backup the following files. Please make sure you are able to open them.
Configure Deja Dup for your root backup:
Run backup then with:
gksu "deja-dup --backup".
At least this worked for me. (You have to configure Deja Dup for root, too, at first - next to your configuration for the "normal" user.)
In 12.04 the following simple command works, if you have sudo privileges:
ALT+CTRL+Tand type this command when you are ready to start backup
sudo deja-dup --backup.
GUI window will open and backup should start.
If you are interested in having it in the Unity launcher that way, there's a pretty easy way to do so, at least in Ubuntu 16.04.
First, open Nautilus as root:
gksu nautilus /usr/share/applications
You are likely to find three Backup app launchers there:
Locate the one which command is plainly deja-dup-preferences:
Now, with that one selected, use Ctrl+C and Ctrl+V to duplicate it.
Right click on the icon that's highlighted and open Properties. They should be the same that you have seen before. Change them so they look like these:
Once you've made the changes, close that window and drag that icon you just have edited into the Unity Launcher so it's locked there.
That's it. Now every time you click on that launcher, it will request your root password and run deja dup as root instead of your current user.
I think you have a few configurations to do with deja-dup first and then run it. Please do try referring to this : http://techie-buzz.com/foss/deja-dup-ubuntu-1.html