--- a/playground/main.c	Fri Oct 03 09:55:51 2025 -0700
+++ b/playground/main.c	Sat Oct 04 07:53:12 2025 -0700
@@ -1,32 +1,83 @@
-#include <pthread.h>
-#include <stdio.h>
-#include <stdlib.h>
-#define NUM_THREADS     5
+// #include <pthread.h>
+// #include <stdio.h>
+// #include <stdlib.h>
+// #define NUM_THREADS     5
+// 
+// void *PrintHello(void *threadid)
+// {
+//    long tid;
+//    tid = (long)threadid;
+//    printf("Hello World! It's me, thread #%ld!\n", tid);
+//    pthread_exit(NULL);
+// }
+// 
+// int main (int argc, char *argv[])
+// {
+//    pthread_t threads[NUM_THREADS];
+//    int rc;
+//    long t;
+//    for(t = 0; t < NUM_THREADS; t++)
+//    {
+//       printf("In main: creating thread %ld\n", t);
+//       rc = pthread_create(&threads[t], NULL, PrintHello, (void *)t);
+//       if (rc)
+//       {
+//          printf("ERROR; return code from pthread_create() is %d\n", rc);
+//          exit(-1);
+//       }
+//    }
+// 
+//    /* Last thing that main() should do */
+//    pthread_exit(NULL);
+// }
 
-void *PrintHello(void *threadid)
-{
-   long tid;
-   tid = (long)threadid;
-   printf("Hello World! It's me, thread #%ld!\n", tid);
-   pthread_exit(NULL);
-}
+#include	<sys/event.h>
+#include	<err.h>
+#include	<fcntl.h>
+#include	<stdio.h>
+#include	<stdlib.h>
+#include	<string.h>
 
-int main (int argc, char *argv[])
+int main(int	argc, char **argv)
 {
-   pthread_t threads[NUM_THREADS];
-   int rc;
-   long t;
-   for(t = 0; t < NUM_THREADS; t++)
-   {
-      printf("In main: creating thread %ld\n", t);
-      rc = pthread_create(&threads[t], NULL, PrintHello, (void *)t);
-      if (rc)
-      {
-         printf("ERROR; return code from pthread_create() is %d\n", rc);
-         exit(-1);
-      }
-   }
+	   struct kevent event;	   /* Event we want to monitor */
+	   struct kevent tevent;   /* Event triggered */
+	   int kq, fd, ret;
+
+	   if (argc != 2)
+	       err(EXIT_FAILURE, "Usage: %s path\n", argv[0]);
+
+	   fd =	open(argv[1], O_RDONLY);
+	   if (fd == -1)
+	       err(EXIT_FAILURE, "Failed to open '%s'",	argv[1]);
+
+	   /* Create kqueue. */
+	   kq =	kqueue();
+	   if (kq == -1)
+	       err(EXIT_FAILURE, "kqueue() failed");
+
+	   /* Initialize kevent	structure. */
+     EV_SET(&event, fd, EVFILT_VNODE, EV_ADD | EV_CLEAR,
+       NOTE_WRITE | NOTE_ATTRIB,
+       0, NULL);
 
-   /* Last thing that main() should do */
-   pthread_exit(NULL);
+	   /* Attach event to the kqueue. */
+	   ret = kevent(kq, &event, 1, NULL, 0,	NULL);
+	   if (ret == -1)
+	       err(EXIT_FAILURE, "kevent register");
+
+	   for (;;)
+     {
+	       /* Sleep	until something	happens. */
+	       ret = kevent(kq,	NULL, 0, &tevent, 1, NULL);
+	       if (ret == -1) {
+		   err(EXIT_FAILURE, "kevent wait");
+	       } else if (ret >	0) {
+		   if (tevent.flags & EV_ERROR)
+		       errx(EXIT_FAILURE, "Event error:	%s", strerror(event.data));
+		   else
+		       printf("Something was written in	'%s'\n", argv[1]);
+	       }
+	   }
+
 }