dtrace discuss - Nov 2006 - arg[0] and arg[1]

what are arg[0] and arg[1]? What file descriptor has to do with arg[0]?

thanks
 
 
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Melanie Pfefer wrote:
> what are arg[0] and arg[1]? What file descriptor has to do with arg[0]?
arg[n] are arguments to the probe, and therefore vary depending on what probe 
is firing.
You''d better have a (good) look in the DTrace user''s guide;
I''m sure a lot
will be clearer once you''ve familiarised yourself with this document.

HTH
-- 
Michael Schuster
Sun Microsystems, Inc.

Melanie,

There is no D built-on array called "arg", but there is one called 
"args", which, as Michael said, refers to the argument list for some 
(but not all) probes.  For example, all of the function boundary trace 
(fbt) probes define the args array, but the system call (syscall) probes 
do not.

If you really mean arg[0] and arg[1], this would have to be an array 
declared by your D program, rather than a built-in array.  I''d be glad 
to give you a better explanation, but I want to make sure you''re
talking
about args and not arg.

Chip

Michael Schuster wrote:
> Melanie Pfefer wrote:
>> what are arg[0] and arg[1]? What file descriptor has to do with arg[0]?
>
> arg[n] are arguments to the probe, and therefore vary depending on 
> what probe is firing.
> You''d better have a (good) look in the DTrace user''s
guide; I''m sure a
> lot will be clearer once you''ve familiarised yourself with this
document.
>
> HTH