Question

If it matters, I am using Mac OS X, but I believe this would apply across OSs. If the answer is different per OS, I would be interested in learning about that as well.

Let’s say that I open a terminal window, enable a few probes, and start collecting data with DTrace.

From a different terminal window, can I ask DTrace what probes have been enabled? If so, how?

Answer 1

I got the following information from Adam Leventhal on a DTrace mailing list. First, he provided this script, which works on Solaris

#!/usr/sbin/dtrace -s

#pragma D option quiet

int i;

tick-100
/i >= `dtrace_nprobes/
{
       exit(0);
}

tick-100
{        printf("%4d %10s %20s %20s %10s %s\n", i,
           stringof(`dtrace_probes[i]->dtpr_provider->dtpv_name),
           stringof(`dtrace_probes[i]->dtpr_mod),
           stringof(`dtrace_probes[i]->dtpr_func),
           stringof(`dtrace_probes[i]->dtpr_name),
           `dtrace_probes[i]->dtpr_ecb != NULL ? "enabled" : "disabled");
       i++
}

Unfortunately, the same kernel variables are not available on Mac OS X due to a bug.