Ubuntu – How to change Mate panel background type from bash

for Ubuntu MATE 16.04 try the following:

1. Open a terminal ( [Ctrl] + [Alt] + [T] )
2. Change to the following directory:
   cd /usr/share/backgrounds/ubuntu-mate-common/
3. Rename the old background picture:
   sudo mv Ubuntu-Mate-Cold.jpg Ubuntu-Mate-Cold.old
4. Copy your image here:
   sudo cp [path/to/your/image] Ubuntu-Mate-Cold.jpg

Note: Do not change the file extension for the background image, even if it is not a jpg but for example a PNG. The background image should be displayed normally anyway.

If you have backup of your dconf database file, which is usually in ~/.config/dconf/user you can restore settings from that database. But some work needs to be done.

Dconf reads database values from a profile file (See wiki here). And the path of that profile file is read from the DCONF_PROFILE environment variable.

1. So, first create a file named user2 in your home directory with content like this

   user-db:user2
   

2. Put your old dconf database file in ~/.config/dconf/ directory with name user2. There should be a file with name user already.

3. Open a terminal and extract the settings from old database

   DCONF_PROFILE=~/user2 dconf dump /org/mate > ~/mate-old
   

   This will dump the values from old dconf database in key-value format in ~/mate-old file.

4. Now load the settings back into the current database

   dconf load /org/mate/ < ~/mate-old
   

This will restore most of the settings of mate.

Extra: If you want you can restore the whole database using / in place of /org/mate. But I'm not recommending this.