My_home_scripts/,wallpaper_changer.sh

#!/bin/bash
# Coding: utf-8
# Editor: www.geany.org
# Created 2016-12-18

# for xfce4 desktop enviroment

# xfconf-query --channel xfce4-desktop --property /backdrop/screen0/monitorVGA-1/workspace0/last-image --set "$(cat ~/LOG/,wallpaper_changer.sh/last_wallpaper)" for setup current wallpaper

export DISPLAY=:0
export XAUTHORITY=/home/a/.Xauthority
export XDG_RUNTIME_DIR=/run/user/$(id -u)

source $HOME/.SCR/lib.sh

fun_log_dir_create $0 365
con_test_not_exist_process

dir_new="$HOME/DATA2/Wallpapers/new"
dir_used="$HOME/DATA2/Wallpapers/used"
last_wall_logfile="$dir_script/last_wallpaper"

read last_wall_path < $last_wall_logfile
fun_analize_command "Read wallpaper path from file"

fun_create_directory "$dir_new" "$dir_used"

if [ -d "$dir_new" ] # if folder with wallpaper exist
then
    wall_name=`ls $dir_new | shuf -n 1`
    fun_analize_command "Get random wallpaper file path"

    new_wall_path="$dir_new/$wall_name"

    fun_echo_variable last_wall_path new_wall_path

    if [ -n "$new_wall_path" ] # if file exist
    then
        xfconf-query --channel xfce4-desktop --property /backdrop/screen0/monitorVGA-1/workspace0/last-image --set "$new_wall_path"
        fun_analize_command "Setup wallpaper $new_wall_path"

        if [ -s "$last_wall_path" ] # if last wallpaper path exist
        then
            if [ "$1" == "del" ] # if first argument is "del"
            then
                rm -rf "$last_wall_path"
                fun_analize_command "Delete file $last_wall_path"
            else
                touch "$last_wall_path"
                fun_analize_command "Set new time date to wallpaper file"

                mv "$last_wall_path" "$dir_used"
                fun_analize_command "Move file to folder $dir_used"
            fi
        fi

        echo "$new_wall_path" > $last_wall_logfile
        fun_analize_command "Write new wallpaper path to file"

        echo "$date_utc" > "${dir_general}/lockfile_wallpaper_changer"

        ,speech_en.sh "New wallpaper installed"
    else
        fun_echo_stadia 11 0 "Files to wallpaper not exist"
    fi
else
    fun_echo_stadia 11 0 "Folder to wallpaper not exist"
fi