Question

I’m having a bit of trouble pulling certain values from a variable in my Perl script on an Ubuntu 12.04 box.

I looked over this page: How to extract string following a pattern

And this is sort of what I want to do. I need to extract a string value after a certain pattern.
Here’s the code I have thus far:

foreach $HDD (@sds)
{
    $hdStat = `hdparm -i $HDD | grep -Po 'Model=\K.*?(?=,)'`;
    $sdModel{$HDD} = $hdStat;
    $hdStat = `hdparm -i $HDD | grep -Po 'SerialNo=\K.*?(?=")'`;
    $sdSerial{$HDD} = $hdStat;
}
foreach $HDD (keys %sdModel)
{
    print $sdModel{$HDD};
}
foreach $HDD (keys, %sdSerial)
{
    print $sdSerial{$HDD};
}

It will return the Model string just fine, but it won’t return the SerialNo string. The code doesn’t have to be with grep; I just modified the code from the link above. And seeing as how I am terrible with regex, I’m probably missing something basic here.

Btw, the purpose of this code is to look through the /dev folder to find any disk drives, and if it does, sets it into an array, where the above script will then get it’s Model # and Serial #.
Also, if anyone sees a better way to do what I’m doing, I am very open to suggestions. I am still very new to Perl (only been with it about a week so far).

Answer 1

First, you don’t print $sdSerial.

Second, you could save some external calls and simplify your regexp with:

foreach my $HDD (@sds) {
    my @hdparm = `hdparm -i $HDD`;
    foreach my $ln (@hdparm) {
        if (my($model, $serial) = ($ln =~ m/Model=(.+?),.+?,\s*SerialNo=(.+)/)) {
            $sdModel{$HDD} = $model;
            $sdSerial{$HDD} = $serial;
        }
    }
}

---

The above can be simplified to:

foreach my $HDD (@sds) {
    my $hdparm = `hdparm -i $HDD`;
    if (my($model, $serial) = ($hdparm =~ m/Model=(.+?),.+?,\s*SerialNo=(.+)/)) {
        $sdModel{$HDD} = $model;
        $sdSerial{$HDD} = $serial;
    }
}