You don't explain exactly what you want to achieve, so I can give some tips here based on a guess: you want to change your wallpaper in certain conditions (for example, one wallpaper every time you restart your computer) or to use a custom file as wallpaper.

In Windows 7 the wallpaper was usually found in .
In Windows 10 you will find it in .

You can also interrogate the registry at

but note the warnings below about programs that are NOT writing a file to disk!

If you want to build your own CMD script, this might be unreliable IF you set the wallpaper not from Windows but from an external program. For example, if I see a nice image in my browser, I set it as wallpaper directly from there. Same for IrfanView. I can easily name another 10 popular programs that could change the wallpaper to a custom path.

Note that some programs are changing the wallpaper without actually writing a file to disk. This can be done by hooking to the Microsoft Windows Desktop window and drawing directly on its canvas. This is how GIF/AVI animations are drawn on desktop.

There is another issue if you build your own script: How to you handle images that don't have same aspect ratio as your desktop, or when desktop resolution changes?

The solution (if I guessed your problem correctly) would be to use a program like John's Background Switcher or BioniX Desktop Background Changer. The latter is much more customizable and can be controlled via command line. It also has auto-detection to detect the best way to resize the image (fill/fit/tile). BioniX can also draw GIF without writing anything to disk (as explained above).

A even better way would be to use the "Lock on folder" option. Set BioniX to change your wallpaper every 60 seconds (don't worry, you won't see a new wallpaper every 60 seconds since you will use only one file). Set BioniX to lock on any folder (let's say ). Inside that folder you put a single file called something like . BioniX will use that file as wallpaper every 60 seconds. Now, every time you want to change the wallpaper you replace the old with your new file. BioniX will see the change you have done to the folder and apply the new file (within 60 seconds).

Let us know what you want to achieve with your script to get a better solution.