dtrace discuss - Jun 2010 - strange behaviour of proc signal-send

Hello,

I have written the following dtrace script to trace who is killing an 
application process:

#!/usr/sbin/dtrace -s
#pragma D option quiet

proc:::signal-send
/args[1]->pr_pid == $1/
{
printf("%20s %20s %12s %12s %12s\n", "SENDER",
"RECIPIENT", "SEND PID",
"REC PID", "SIGNAL");
printf("%20s %20s %12d %12d %12d\n", execname, 
stringof(args[1]->pr_fname), pid, args[1]->pr_pid, args[2]);
}

When I interrupt (Ctrl+C) the dtrace script the application process got 
terminated and the following trace appears in the output of the dtrace 
script:

root at hkctmd01 # /tmp/signal.d 18080
              SENDER            RECIPIENT     SEND PID      REC 
PID       SIGNAL
               sched                  p_ctmag                0        
            18080           18
              SENDER            RECIPIENT     SEND PID      REC 
PID       SIGNAL
               sched                  p_ctmag                0        
            18080           18
              SENDER            RECIPIENT     SEND PID      REC 
PID       SIGNAL
               sched                  p_ctmag                0        
            18080           18
^C
              SENDER            RECIPIENT     SEND PID      REC 
PID       SIGNAL
                sshd                  p_ctmag            24510        
        27861            2

Questions is:

- Why the application process got terminated when I kill the dtrace script:
- Why the dtrace script trace also signal sent to process 27861 even if 
I have filtered for proc 18080?

Thanks in advance!



-- 
 
Oracle <http://www.oracle.com/>*

Andrea Cucciarre'' - System engineer

*Systems Technology Service Centre
Solaris and Networking
Global Services Delivery

Phone: +39 0264152047
Email: andrea.cucciarre at oracle.com
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