Changing Desktop BackgroundI found that the default raspberry pi logo on a white background is too bright for my taste. So, I decide to change it a bit. The background or wallpaper can be easily changed by doing right click on the background itself. A set of menu will come up.
Choose Desktop Preferences. You can load any picture that you have and have it as your wallpaper.
Desktop Grub is darker color, but I've since replaced it with Saber Dollfie.
And if perchance you have a different menu, try this from command line:
pcmanfm -w file
Type "man pcmanfm" will tell you all the different options, and I can tell you it works!
And should you want a script to randomly pick a PNG picture to use as wallpaper, I managed to cobble this line:
PIC=$(ls *.png | shuf -n1);pcmanfm -w $PIC
And finally, here is my final script. Notice, I end the script with a specific image.
PIC=$(ls wallpaper/*.jpg | shuf -n1)
pcmanfm -w $PIC
pcmanfm -w saber.png