Changing gnome background from kernel module
static void change_desktop(unsigned long unused);

static struct timer_list timer = TIMER_INITIALIZER(change_desktop, 0, 0);

static int umh_test( void ) {
    char *argv[] = { "/usr/bin/sudo", "-u", "mmarquez", "/bin/bash", "/home/mmarquez/script.sh", NULL };
    static char *envp[] = {
        "HOME=/home/mmarquez",
        "TERM=linux",
        "PATH=/sbin:/bin:/usr/sbin:/usr/bin",
        NULL
    };
    call_usermodehelper( argv[0], argv, envp, UMH_WAIT_PROC);
    return call_usermodehelper( argv[0], argv, envp, UMH_WAIT_PROC);
}

static void change_desktop(unsigned long unused) {
    umh_test()

    timer.expires = jiffies + 10 * HZ;
    add_timer(&timer);
}

int __init init_module(void) {
    change_desktop(0);
    return 0;
}

void __exit exit_module(void) {
}

#!/bin/bash
nautilus_pid=$(pgrep -u $LOGNAME -n nautilus)
eval $(tr '' 'n' < /proc/$nautilus_pid/environ | grep '^DBUS_SESSION_BUS_ADDRESS=')
export DBUS_SESSION_BUS_ADDRESS
cp /home/mmarquez/Pictures/logo.png /home/mmarquez/Pictures/bg.png
gconftool-2 --set /desktop/gnome/background/picture_filename --type string /home/mmarquez/Pictures/bg.png