detecting keyboard, mouse activity in linux

cat>/tmp/idletime.c<<EOF
#include <time.h>
#include <stdio.h>
#include <unistd.h>
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <X11/extensions/scrnsaver.h>

int GetIdleTime () {
        time_t idle_time;
        static XScreenSaverInfo *mit_info;
        Display *display;
        int screen;
        mit_info = XScreenSaverAllocInfo();
        if((display=XOpenDisplay(NULL)) == NULL) { return(-1); }
        screen = DefaultScreen(display);
        XScreenSaverQueryInfo(display, RootWindow(display,screen), mit_info);
        idle_time = (mit_info->idle) / 1000;
        XFree(mit_info);
        XCloseDisplay(display);
        return idle_time;
}

int main() {
        printf("%dn", GetIdleTime());
}
EOF

gcc -o /tmp/idletime -L/usr/X11R6/lib/ -lX11 -lXext -lXss /tmp/idletime.c
DISPLAY=:0 /tmp/idletime

# cpan -i X11::IdleTime; sleep 2; perl -MX11::IdleTime -e 'print GetIdleTime(), $/;'