bunpen: execute the given argv

pkgs/additional/bunpen/src/main.ha

@@ -1,6 +1,20 @@
 // vim: set shiftwidth=2 :
 use fmt;
+use strings;
+use os;
+use os::exec;
+
+fn do_exec(args: []str) never = {
+  let joined = strings::join(" ", args...);
+  fmt::printfln("exec: {}", joined)!;
+  free(joined);
+
+  let cmd = os::exec::cmd(args[0], args[1..]...)!;
+  os::exec::exec(&cmd);
+};
 
 export fn main() void = {
-  fmt::println("Hello world!")!;
+  let my_name = os::args[0];
+  let exec_line = os::args[1..];
+  do_exec(exec_line);
 };