Sample script to set the desktop with desktoppr

setdesktop.sh

#!/bin/sh

##
## sets the desktop using `desktoppr`
##

export PATH=/usr/bin:/bin:/usr/sbin:/sbin

# set the path to the desktop image file here
picturepath="/Library/Desktop Pictures/BoringBlueDesktop.png"


# verify the image exists
if [ ! -f "$picturepath" ]; then
    echo "no file at $picturepath, exiting"
    exit 1
fi

# verify that desktoppr is installed
desktoppr="/usr/local/bin/desktoppr"
if [ ! -x "$desktoppr" ]; then
    echo "cannot find desktoppr at $desktoppr, exiting"
    exit 1
fi

# get the current user
loggedInUser=$( echo "show State:/Users/ConsoleUser" | scutil | awk '/Name :/ && ! /loginwindow/ { print $3 }' )

# test if a user is logged in
if [ -n "$loggedInUser" ]; then
    # get the uid
    uid=$(id -u "$loggedInUser")
    # do what you need to do
    sudo -u "$loggedInUser" "$desktoppr" "$picturepath"
else
    echo "no user logged in, no desktop set"
fi

It works for me and I am on the latest 10.15.4 (19E287). At this point you should check: is desktoppr installed correctly in the expected path? is it the latest version? Is the image you reference in picturepath installed when the script runs? is the path correct?

you might want to place a set -x at the beginning the of the script to get a detailed trace while it runs.

Thanks for this and the desktoppr tool!

In this script why is there this?
# get the uid
uid=$(id -u "$loggedInUser")
I don't see it used anywhere

because an earlier version of the script used

launchctl asuser "$uid" "$desktoppr" "$picturepath"