This is a shell script I wrote to automate the process of downloading National Geographic photo of the day, and set it as background in linux. The script downloads the photo of the day in the same directory that it resides. You can use cron to make it automatically running everyday.
Although National Geographic posts a photo everyday, not all the photos come with a high quality format. So the script checks whether a wallpaper format exists or not. If so, it downloads the photo into the same directory the script resides.
All you need to do is to create a directory for your wallpapers and put the script in there, e.g.:
cd ~/Pictures/
git clone https://github.com/samanbarghi/ngphotodownloader.git NGWallpapers
You can setup your cron to run daily to download and set the background. Add the following to current user's crontab by issueing:
crontab -u username -e
Replace username with your username. Make sure to export PATH in your crontab
PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin
0 12 * * * sh /home/yourusername/Pictures/NGWallpapers/ngwallpaper.sh
In my case since I am running the script on my laptop, and my laptop is not always on; I call the script every 3 hours to make sure it runs at least once each day. Don't worry about duplicates, the script will not download the image if it already exists in the directory. The overhead of the script on cpu/memory/network is negligible, so don't worry about calling the script 8 times a day:
00 */3 * * * sh /home/yourusername/Pictures/NGWallpapers/ngwallpaper.sh
Keep in mind that DBUS_SESSION_BUS_ADDRESS is only detected for cinnamon, gnome, and mate. If other managers are runnign you need to modify the following lines in the script so pgrep catch the right pid:
PID=$(pgrep -o "cinnamon-sess|gnome-sess|mate-sess")
Refer to http://stackoverflow.com/questions/10374520/gsettings-with-cron for more information.