This guide will show you how to have your wallpaper changing automatically using a program called Drapes. Either search for it online and install it via directions given, or open up your package manager (like Synaptic) and search for drapes, then mark it for installation (or sudo apt-get install drapes in the terminal). Once installed, don’t be surprised if you don’t find a launcher for it anywhere; this doesn’t matter as you can start it via the terminal, configure it, and have it load each time Ubuntu does.
Once installed, open a terminal, type drapes and hit Enter. You will now see a little icon near the system tray clock (should look like a monitor with curtains). Right-click that and choose Preferences.
In the first tab, Display, you will see you can +Add and -Remove wallpapers, so browse to any folders with wallpapers and select those you want included. To select all in a folder, click on one and then Ctrl+A to select all. To make building your list easier, you could even create a new folder just for these, then browse all your pictures and wallpapers folders and copy your favourites into this new folder, then just import all those in the one folder to the list in Drapes. Not only does doing this beforehand make it easier for adding the wallpapers all at once, you can also get Drapes to check for changes to a folder, so it makes sense to have a folder for this purpose.
While you are on the Display tab, you will also see that you can change the Style via a drop-down menu. These display modes are Centered, Fill Screen, Scaled, Tiled, and Zoom. You may want to play around with this if you have many pictures that aren’t exactly your screen size and shape (especially if you have a widescreen display).
In the second tab, General, you will see Startup options, and you select “Switch wallpaper on start” if desired. You will also see the autostart option “Start Desktop Drapes on start“, but if you check that don’t be surprised if Drapes doesn’t load by itself on the next reboot. But don’t worry, as a built-in feature of Ubuntu makes it easy to add anything to the boot process. But for now, we just need to configure Drapes before shutting it down properly (as closing the terminal will close down Drapes but not save any of the new settings).
Now, you’ll see you can change the “Timing selection“, which means the interval between changes. The default should be 15 mins, but you can lower it to 5 mins or as high as 2 hours.
At the bottom you will see “Wallpaper search directory” where you can check “Monitor this directory for new wallpapers“. If you check that, you can then browse for your wallpaper folder and select that; after that, you can just add new pictures and wallpapers into that folder, and you won’t need to import them manually (new wallpapers might not get noticed till the next reboot).
To make sure everything you’ve just done is saved, you will need to manually exit. Right-click the Drapes icon in your panel and choose Quit. If you close the terminal first, the settings will be lost; once you’ve quit properly, you can close the terminal (you will note it says the settings have been saved).
Finally, to have it start with each boot, go to System > Preferences > Startup Applications, click the +Add button, and fill in the info (for Name, you can put Drapes; the Command is simply drapes, and for Comment you can put Wallpaper Changer).
Upon your next reboot, Drapes will load and continue to do so until you disable it.