Windows batch script to switch desktop background

Question

Is there a way to check what a user currently has as their background and then changing it depending on what it is? For example: I want a white background during day time and a black background for night time. Running the script would check the current background, if it is white it will switch to the black background, and if it is black it will switch to the white.

I'm a little unfamiliar with Windows batch script and I'm seeking some tips and advice on how I can accomplish the task above. Here is what I've been able to find so far:

@echo off
call :quiet>nul 2>&1
goto :EOF

:quiet


:: Configure Wallpaper 
REG ADD "HKCU\Control Panel\Desktop" /V Wallpaper /T REG_SZ /F /D "%SystemRoot%\energybliss.bmp"
REG ADD "HKCU\Control Panel\Desktop" /V WallpaperStyle /T REG_SZ /F /D 0
REG ADD "HKCU\Control Panel\Desktop" /V TileWallpaper /T REG_SZ /F /D 2


:: Configure the screen saver.
:: REG ADD "HKCU\Control Panel\Desktop" /V SCRNSAVE.EXE /T REG_SZ /F /D "%SystemRoot%\System32\scrnsave.scr"
:: REG ADD "HKCU\Control Panel\Desktop" /V ScreenSaveActive /T REG_SZ /F /D 1


:: Set the time out to 900 seconds (15 minutes).
:: REG ADD "HKCU\Control Panel\Desktop" /V ScreenSaveTimeOut /T REG_SZ /F /D 900


:: Set the On resume, password protect box 
:: REG ADD "HKCU\Control Panel\Desktop" /V ScreenSaverIsSecure /T REG_SZ /F /D 1


:: Remove the user's ability to see the Screen Saver, background, and appearance tabs of Display Properties. 
::REG ADD "HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\System" /V NoDispScrSavPage /T REG_DWORD /F /D 1
::REG ADD "HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\System" /V NoDispBackgroundPage /T REG_DWORD /F /D 1
::REG ADD "HKCU\Software\Microsoft\Windows\CurrentVersion\Policies\System" /V NoDispAppearancePage /T REG_DWORD /F /D 1

:: Make the changes effective immediately
%SystemRoot%\System32\RUNDLL32.EXE user32.dll, UpdatePerUserSystemParameters

Solution

You can use code like that:

@echo off

:: '>nul 2>&1' was moved to other place
call :quiet
exit /b

:quiet
    :: Put there wallpaper name (with extension, bigger that 8 symbols)
    set "Wallpaper.Night.BadWrited=Wallpaper1.bmp"

    :: It is a dirty hack and example of bad code
    for /F "tokens=*" %%a in ('reg query "HKCU\Control Panel\Desktop" /v Wallpaper') do     set "Wallpaper.Current.BadWrited=%%a"

    :: Take last 8 symbols of wallpaper name. Change number of symbols to your own  minimal
    set "Wallpaper.Current.BadWrited=%Wallpaper.Current.BadWrited:~-8%"
    set "Wallpaper.Night.BadWrited=%Wallpaper.Night.BadWrited:~-8%"

    if "%Wallpaper.Current.BadWrited%"=="%Wallpaper.Night.BadWrited%" (
        call :MakeDayWallpaper>nul 2>&1
    ) else (
        call :MakeNightWallpaper>nul 2>&1
    )
exit /b

:MakeDayWallpaper
    echo Day wallpaper setted
    :: Put your code here
exit /b

:MakeNightWallpaper
    echo Night wallpaper setted 
    :: Put your code here
exit /b

But i recommend to use the system scheduler. You can acces it from control panel, 'Scheduled Tasks' or something. You can make 2 files named 'makeday.bat' and 'makenight.bat'. Scheduler will run them every day at needed time