First, find the process id:
```objectivec
$ ps -ef|grep Grab
501 50335 319 0 0:02.11 ?? 0:04.40 /Applications/Utilities/Grab.app/Contents/MacOS/Grab -psn_0_7309048
```
The pid is 50335 so create a D program that captures the Objective-C calls for that process:
```objectivec
objc50335:::entry
{
printf("%s %s\n", probemod, probefunc);
}
```
Save the code in a file called grab.trace.d and start tracing by executing this command:
```objectivec
sudo dtrace -s grab.trace.d > trace.log
```
Output is sent to the trace.log file.