Mac: Getting path of current desktop picture from terminal

I found that the answer can be shortened to one line:

osascript -e 'tell app "finder" to get posix path of (get desktop picture as alias)'

Like this:

osascript -e '
    tell application "Finder"
    set theDesktopPic to desktop picture as alias
    set theName to posix path of theDesktopPic
    end tell'

/Users/mark/Documents/Carbon fibre.png