dtrace discuss - Sep 2009 - Pass argument to dtrace script for use as predicate

Greetings to everyone.
I wrote a script to calculate how much time is spent on the system
calls originating from a specific executable:

#!/usr/sbin/dtrace -s

/*
 * Generate table statistics on how much time is spent on every system call,
 * for a given program (its name is assigned to $1).
 */

#pragma D option quiet

syscall:::entry
/execname == $1/
{
        self->sstart = timestamp;
}

syscall:::return
/execname == $1/
{
        @timestats[probefunc] = avg(timestamp - self->sstart);
        @cntstats[probefunc] = count();
        self->sstart = 0;
}

tick-1sec
{
        printf("%20s | %20s | %5s\n", "Function",
"<ns> over 1-sec period",
                                "Count");
        printa("%20s   %22 at d  %6 at d\n", @timestats, @cntstats);
        printf("\n");
}

Here''s the deal:

1. If I leave $1 without double quotes " and the execname I pass has a
dot in it, it (accidentally?) works ok:
$ pfexec ./temp.sh
...

In another terminal:
$ pfexec ./lala.d temp.sh

            Function | <ns> over 1-sec period | Count
              getgid                      873       2
              getuid                      981       2
               umask                     1032       2
           sysconfig                     1077       9
           getrlimit                     1279       1
              llseek                     1290       4
               gtime                     1365       1
              getpid                     1437      25

2. If I leave $1 without double quotes " and the execname doesn''t
have
a dot in it, it fails with:
$ pfexec ./lala.d temp
dtrace: failed to compile script ./lala.d: line 11: failed to resolve
temp: Unknown variable name

3. If I surround $1 with double quotes, it fails not matter what the
supplied argument is:
$ pfexec ./lala.d temp.sh
dtrace: failed to compile script ./lala.d: line 31: extraneous
argument ''temp.sh'' ($1 is not referenced)
$ pfexec ./lala.d temp
dtrace: failed to compile script ./lala.d: line 31: extraneous
argument ''temp'' ($1 is not referenced)


I guess that I''m wrong in all 3 cases, but just being lucky in 1).
How could I pass an argument (possibly containing spaces) to dtrace
script and use that as a predicate for execname ?

Best regards,
Stathis

2009/9/12 Stathis Kamperis <ekamperi at
gmail.com>:
> 2. If I leave $1 without double quotes " and the execname
doesn''t have
> a dot in it, it fails with:
> $ pfexec ./lala.d temp
> dtrace: failed to compile script ./lala.d: line 11: failed to resolve
> temp: Unknown variable name
Ok, I got lucky with google this time:
http://solaris.reys.net/passing-command-line-parameters-to-dtrace-scripts

I have to write:
$ pfexec ./lala.d ''"temp"''

for dtrace to treat it as string argument.
> 3. If I surround $1 with double quotes, it fails not matter what the
> supplied argument is:
> $ pfexec ./lala.d temp.sh
> dtrace: failed to compile script ./lala.d: line 31: extraneous
> argument ''temp.sh'' ($1 is not referenced)
> $ pfexec ./lala.d temp
> dtrace: failed to compile script ./lala.d: line 31: extraneous
> argument ''temp'' ($1 is not referenced
I still can''t figure this out. Does "$1" inside a script make
dtrace
perceive it as a literal string ''$1'' ?

Cheers,
Stathis

For string arguments use $$1

-Angelo


On Sep 12, 2009, at 3:07 PM, Stathis Kamperis wrote:
> Greetings to everyone.
> I wrote a script to calculate how much time is spent on the system
> calls originating from a specific executable:
>
> #!/usr/sbin/dtrace -s
>
> /*
> * Generate table statistics on how much time is spent on every  
> system call,
> * for a given program (its name is assigned to $1).
> */
>
> #pragma D option quiet
>
> syscall:::entry
> /execname == $1/
> {
>        self->sstart = timestamp;
> }
>
> syscall:::return
> /execname == $1/
> {
>        @timestats[probefunc] = avg(timestamp - self->sstart);
>        @cntstats[probefunc] = count();
>        self->sstart = 0;
> }
>
> tick-1sec
> {
>        printf("%20s | %20s | %5s\n", "Function",
"<ns> over 1-sec
> period",
>                                "Count");
>        printa("%20s   %22 at d  %6 at d\n", @timestats,
@cntstats);
>        printf("\n");
> }
>
> Here''s the deal:
>
> 1. If I leave $1 without double quotes " and the execname I pass has a
> dot in it, it (accidentally?) works ok:
> $ pfexec ./temp.sh
> ...
>
> In another terminal:
> $ pfexec ./lala.d temp.sh
>
>            Function | <ns> over 1-sec period | Count
>              getgid                      873       2
>              getuid                      981       2
>               umask                     1032       2
>           sysconfig                     1077       9
>           getrlimit                     1279       1
>              llseek                     1290       4
>               gtime                     1365       1
>              getpid                     1437      25
>
> 2. If I leave $1 without double quotes " and the execname
doesn''t have
> a dot in it, it fails with:
> $ pfexec ./lala.d temp
> dtrace: failed to compile script ./lala.d: line 11: failed to resolve
> temp: Unknown variable name
>
> 3. If I surround $1 with double quotes, it fails not matter what the
> supplied argument is:
> $ pfexec ./lala.d temp.sh
> dtrace: failed to compile script ./lala.d: line 31: extraneous
> argument ''temp.sh'' ($1 is not referenced)
> $ pfexec ./lala.d temp
> dtrace: failed to compile script ./lala.d: line 31: extraneous
> argument ''temp'' ($1 is not referenced)
>
>
> I guess that I''m wrong in all 3 cases, but just being lucky in 1).
> How could I pass an argument (possibly containing spaces) to dtrace
> script and use that as a predicate for execname ?
>
> Best regards,
> Stathis
> _______________________________________________
> dtrace-discuss mailing list
> dtrace-discuss at opensolaris.org

From http://wikis.sun.com/display/DTrace/Scripting;

If you want your D macro arguments to be interpreted as string tokens 
even if they match the form of an integer or identifier, prefix the 
macro variable or argument name with two leading dollar signs (for 
example, $$1) to force the D compiler to interpret the argument value as 
if it were a string surrounded by double quotes. All the usual D string 
escape sequences (see Table 2?5) are expanded inside of any string macro 
arguments, regardless of whether they are referenced using the $arg or 
$$arg form of the macro. If the defaultargs option is set, unspecified 
arguments that are referenced with the $$arg form have the value of the 
empty string ("").


If you''re passing a string, use $$1.

/jim

Stathis Kamperis wrote:
> 2009/9/12 Stathis Kamperis <ekamperi at gmail.com>:
>   
>> 2. If I leave $1 without double quotes " and the execname
doesn''t have
>> a dot in it, it fails with:
>> $ pfexec ./lala.d temp
>> dtrace: failed to compile script ./lala.d: line 11: failed to resolve
>> temp: Unknown variable name
>>     
> Ok, I got lucky with google this time:
> http://solaris.reys.net/passing-command-line-parameters-to-dtrace-scripts
>
> I have to write:
> $ pfexec ./lala.d ''"temp"''
>
> for dtrace to treat it as string argument.
>
>   
>> 3. If I surround $1 with double quotes, it fails not matter what the
>> supplied argument is:
>> $ pfexec ./lala.d temp.sh
>> dtrace: failed to compile script ./lala.d: line 31: extraneous
>> argument ''temp.sh'' ($1 is not referenced)
>> $ pfexec ./lala.d temp
>> dtrace: failed to compile script ./lala.d: line 31: extraneous
>> argument ''temp'' ($1 is not referenced
>>     
>
> I still can''t figure this out. Does "$1" inside a script
make dtrace
> perceive it as a literal string ''$1'' ?
>
> Cheers,
> Stathis
> _______________________________________________
> dtrace-discuss mailing list
> dtrace-discuss at opensolaris.org
>