gnome 3 - desktop background

gsettings set org.gnome.desktop.background picture-options "centered"
gsettings set org.gnome.desktop.background primary-color "#000000"
gsettings set org.gnome.desktop.background secondary-color "#000000"
gsettings set org.gnome.desktop.background color-shading-type "solid"

#!/bin/bash
GNOMEBGFOLDER=/usr/share/backgrounds/gnome
GDMUSER=Debian-gdm

# FULL PATH to the wallpaper :
#MYBG=$HOME/Documents/images/wallpapers/treeflower/wallpaper-1280x800.png
MYBG=$HOME/Documents/images/wallpapers/crazyrough.jpg

# Desktop background
GSETTINGS_BACKEND=dconf gsettings set org.gnome.desktop.background picture-uri \
  "file://$MYBG"

# Login screen (GDM)
id $GDMUSER || GDMUSER=gdm
sudo cp $MYBG $GNOMEBGFOLDER
basebg=$(basename $MYBG)
newbg=$GNOMEBGFOLDER/$basebg
xhost +SI:localuser:$GDMUSER
sudo su - $GDMUSER -s /bin/bash --command="
dbus-launch
GSETTINGS_BACKEND=dconf gsettings set org.gnome.desktop.background picture-uri "file://$newbg";
GSETTINGS_BACKEND=dconf gsettings get org.gnome.desktop.background picture-uri;
"
xhost -SI:localuser:$GDMUSER

# Lock screen
# Resolution : cf xdpyinfo  | grep 'dimensions:'
cat <<EOF>/tmp/lockscreen.xml
<background>
  <static>
    <duration>8640000.0</duration>
    <file>
      <size width="1600" height="900">$newbg</size>
    </file>
  </static>
</background>
EOF
sudo mv /tmp/lockscreen.xml /usr/share/images/desktop-base/lockscreen.xml
sudo ln -sf /usr/share/images/desktop-base/lockscreen.xml /etc/alternatives/desktop-background.xml


echo -e "\nYou need to restart the service gdm3 in a text console (i.e. tty1), as root."