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List:       opensolaris-dtrace-discuss
Subject:    Re: [dtrace-discuss] How to use pid provider on certain processes.
From:       Chad Mynhier <cmynhier () gmail ! com>
Date:       2009-05-11 21:01:36
Message-ID: 3cf3989e0905111401r63665ea4ie983f87d39906b63 () mail ! gmail ! com
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On Mon, May 11, 2009 at 4:37 PM, Brian Utterback
<brian.utterback@sun.com> wrote:
> I know this has been asked before, but I can't seem to find the answer.
>
> I have a process I want to trace with the pid provider, but the process gets
> started once in a while. There is only one process by its name running at a
> time.
>
> I can't see how to use the pid provider in these circumstances.
> Specifically, in this case the process is called "ntpd" and I want to trace
> all calls to memcpy. Any ideas how to do this?

I can think of a couple of ways.  One is to trace exec-success, stop()
if execname == "ntpd", and prun it via system().  Something like this:

#!/usr/sbin/dtrace -qws

proc:::exec-success
/ execname == "ls" /
{
        stop();
        system("/tmp/trace-ls.d -p %d", pid);
}

The second DTrace script will start ls (or in your case, ntpd)
running, so there's no need for a prun or equivalent.

The second way is to just replace ntpd with a wrapper DTrace script
that calls the real version of ntpd.

Chad
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