first commit

user/echo.c

@@ -0,0 +1,19 @@
+#include "kernel/types.h"
+#include "kernel/stat.h"
+#include "user/user.h"
+
+int
+main(int argc, char *argv[])
+{
+  int i;
+
+  for(i = 1; i < argc; i++){
+    write(1, argv[i], strlen(argv[i]));
+    if(i + 1 < argc){
+      write(1, " ", 1);
+    } else {
+      write(1, "\n", 1);
+    }
+  }
+  exit(0);
+}