Octavian has asked for the wisdom of the Perl Monks concerning the following question:

This question is mainly for the UNIX users out there...I need to write a program that will display all the configurable kernal parameters on a system, show their formula, and show their resolved value. what I have so far is below, but to explain it first, I run kmtune -S /stand/system and throw it into an array to get all the parameters I need, and it displays the formula for them if any....the hexidecimal values are no problem, along with evaluating simple formulas...where I run into a snag is when a formula relys on the result of another parameter. I guess I dont understand enough about how to get around this to be able to explain it correctly, but if you know what kmtune's output looks like, you will see where I am running into a snag...here is what I got so far.. 
#!/usr/local/bin/perl
chomp(@datafile = `/usr/sbin/kmtune -S /stand/system`);
foreach (@datafile)
{
        tr/[A-Z]/[a-z]/;
        ($key,$value) = split(/\s+/);
        if ($key eq "Parameter" || $value eq "") { next; }
        if (grep/^0x/i,$value) { $value = hex($value); }
        $var{$key} = $value;
}
foreach $key(keys %var)
{
### Evaluating the hash variable generates errors on the ones that hav
+e varibales embedded in them.
        #print "$key:", eval $var{$key}, "\n";

### This works, but doesnt resolve formulas in the variables.
        print "$key:", $var{$key}, "\n";
}

[download]
Any help or ideas would be greatly appreciated...and if there is another way to get the formulas AND the end result, that would work, but I would prefer to find a nifty perly way to do it :)

Replies are listed 'Best First'.
(jeffa) Re: resolving variable names within variable names.
by jeffa (Bishop) on Jun 04, 2002 at 15:43 UTC
    We discussed this problem recently at Parse C-like define statements. Using a variation on the solution presented by danger and sfink: 
    # after your first foreach loop
foreach my $key (keys %var) {
   1 while $var{$key} =~ s/([a-z_]+)/$var{$1}/;
   $var{$key} = eval "$var{$key}";
}

    [download]
    should do the trick.

    On another note - i would remove the first line in your first foreach loop (the one with the tr) and change the last line of that loop to: 

    $var{$key} = "\L$value\E";

    [download]
    UPDATE - or maybe not :) - i overlooked the fact that the first few lines of the output have uppercase keys - my mistake.

    jeffa

    L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)
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[d/l]
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      you da man...that worked great....I thank you for that...I get in that deep and my brain starts to hurt....course now looking at the logic of it it seems easy :P
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Re: resolving variable names within variable names.
by Octavian (Monk) on Jun 04, 2002 at 14:58 UTC
    I got a couple requests from people to display some output from kmtune, since alot of you dont have it...so here is all of the output from kmtune:
    Read more... (4 kB)
    as you can see...some of the values are numbers, but other are math formulas...and some are math formulas that contain other variables in it.... eventually it all resolves down to just a number... hope this helps :)
[reply]
[d/l]

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