How to get dd to print transfer stats in MacOS?

For MacOS (Mavericks), I am making a shell script to gather transfer stats over time for command dd.

The manual page says:

If dd receives a SIGINFO (see the status argument for stty(1)) signal, the current input and output block counts will be written to the standard error output in the same format as the standard completion message.

Therefore, just like in Linux, I tried:

kill -INFO <pid_of_dd>

The command completes successfully with status 0, however the terminal in which dd process connected to, there is no stats information in standard output/standard error.

So what is the correct way to get dd to print stats in its output?

Solution

It seems to work for me:

$ dd if=/dev/zero of=/dev/null bs=1k &
[1] 33990
$ kill -INFO 33990
4787784+0 records in
4787784+0 records out
4902690816 bytes transferred in 4.260769 secs (1150658706 bytes/sec)
$ kill -INFO 33990
8357846+0 records in
8357846+0 records out
8558434304 bytes transferred in 7.428820 secs (1152058392 bytes/sec)
$ kill 33990
$ ps
  PID TTY           TIME CMD
 1342 ttys000    0:00.02 -bash
 2290 ttys001    0:00.17 -bash
[1]+  Terminated: 15          dd if=/dev/zero of=/dev/null bs=1k
$