As Fletch points out, you might as well use Perl to pull out the line you want from the prtconf output. It is a good idea to use strict; and three argument opens.

use strict;
use warnings;

my $prtconfCmd = q{/usr/sbin/prtconf};
open my $prtconfFH, q{-|}, $prtconfCmd
   or die qq{fork: $prtconfCmd: $!\n};

my $memVal = q{};

while ( <$prtconfFH> )
{
    next unless m{^Mem.*?:\s+(\d+\s+\S+)};
    $memVal = $1;
    last;
}

close $prtconfFH;

print qq{Total memory is: $memVal\n};
[download]

I hope this is of use.

Cheers,

JohnGG