linux_background.sh

#!/bin/bash

default=$(shuf -n 1 subreddits)
sub=${1:-$default}

#find any imgur links from our chosen subreddit and pick a random one
pattern="http://i.imgur.com.\w{0,}.jpg"
url=$(curl -s "https://www.reddit.com/r/$sub/top" | grep -Eo $pattern | shuf -n 1)

#download the image
filename=$(echo $url | grep -Eo "\w{0,}.jpg")
wget -q $url

#make sure we have a dir to store the images
if [ ! -d $HOME/reddit_backgrounds ]
then
    mkdir $HOME/reddit_backgrounds
fi

#put the file into our dir for these images
mv $filename $HOME/reddit_backgrounds/.
background=$HOME/reddit_backgrounds/$filename

# use echo $DESKTOP_SESSION to determine desktop used. If $DESKTOP_SESSION does not work, try $GDMSESSION or $XDG_CURRENT_DESKTOP
# attempt to figure out the desktop session to change the background
case "$DESKTOP_SESSION" in
'xfce')
    xfconf-query --channel xfce4-desktop --property /backdrop/screen0/monitor0/image-path --set $background
;;
'mate')
    gsettings set org.mate.background picture-filename $background
;;
'gnome')
    gesttings set org.gnome.desktop.background picture-uri file:///$background
;;
*)
    notify-send "Unsupported desktop environment."
    exit
;;
esac

#notify where the wallpaper comes from
notify-send "Today's wallpaper is from /r/"$sub