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4

Setting cron to run a shell script: random wallpaper from a webpage

rated 0 times [ 4] [ 0] / answers: 1 / hits: 2631 / 2 Years ago, fri, may 27, 2022, 7:11:53

I have written a shell script which downloads random wallpaper from a web-page and sets it as a background every 5 hours. Here is the script:

#!/bin/bash



countervar=1;

finish=0;

cd /home/guinness/.rwallpaper/

if [ -f counter ]

then

    countervar=`cat counter`

fi



for (( i=$countervar; c<=2000000; i++ ))

do

   echo $i > "counter"

   if [ ! -f wallpaper-$i.jpg ]

   then

    wget "http://wallpapers.wallbase.cc/rozne/wallpaper-$i.jpg"



    if [ -f wallpaper-$i.jpg ]

    then

        gsettings set org.gnome.desktop.background picture-uri "file:///home/guinness/.rwallpaper/wallpaper-$i.jpg"

        exit

    fi

   fi

done

If I run a this script it works like a charm. I use cron to run this every 5 hours. The problem, is that it runs every 5 hours and successfully downloads the next image but it doesn't set it as a wallpaper. Can anybody tell me what can be the problem?

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tocklftime

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2 Years ago

answered 2 Years ago neasinient · Accepted Answer

This is happen because cron uses only a very restricted set of environment variables. The only one environment variable that is responsible for running in the right way the script from the question when this is set as a cron job is DBUS_SESSION_BUS_ADDRESS.

So, you must to export DBUS_SESSION_BUS_ADDRESS environment variable in your script. See more explanations in my answer here.

In the end, your script should look like:

#!/bin/bash



PID=$(pgrep gnome-session)

export DBUS_SESSION_BUS_ADDRESS=$(grep -z DBUS_SESSION_BUS_ADDRESS /proc/$PID/environ|cut -d= -f2-)



countervar=1;

finish=0;

cd /home/guinness/.rwallpaper/

if [ -f counter ]

then

    countervar=`cat counter`

fi



for (( i=$countervar; c<=2000000; i++ ))

do

   echo $i > "counter"

   if [ ! -f wallpaper-$i.jpg ]

   then

    wget "http://wallpapers.wallbase.cc/rozne/wallpaper-$i.jpg"



    if [ -f wallpaper-$i.jpg ]

    then

        gsettings set org.gnome.desktop.background picture-uri "file:///home/guinness/.rwallpaper/wallpaper-$i.jpg"

        exit

    fi

   fi

done