implement cp and mv and improve rm

util/fnck.c

@@ -0,0 +1,15 @@
+/* See LICENSE file for copyright and license details. */
+#include <sys/stat.h>
+#include "../util.h"
+
+void
+fnck(const char *a, const char *b, int (*fn)(const char *, const char *))
+{
+	struct stat sta, stb;
+
+	if(stat(a, &sta) == 0 && stat(b, &stb) == 0
+	&& sta.st_dev == stb.st_dev && sta.st_ino == stb.st_ino)
+		eprintf("%s -> %s: same file\n", a, b);
+	if(fn(a, b) == -1)
+		eprintf("%s -> %s:", a, b);
+}