#!/usr/bin/perl

use Win32::API;
use File::Basename;

use constant SPI_SETDESKWALLPAPER  => 20;
use constant SPIF_UPDATEANDSENDINI => 3;
use constant NULL                  => 0;

$path = '/home/desktops/';

my @files = <"$path/*">;

my $file = basename($files[rand @files]);

system("convert '$path$file' /desktop.bmp");

my $syspinf = Win32::API->new('user32','SystemParametersInfo', [I,I,P,I], I)
 or die "Could not import function.\n";
 
$syspinf->Call(SPI_SETDESKWALLPAPER, 0, "C:\\cygwin\\desktop.bmp", SPIF_UPDATEANDSENDINI);