use strict;
use warnings;

my %cpusocket;

open CPUINFO, "/proc/cpuinfo" or warn;
foreach(<CPUINFO>) {
    if (/^physical\sid\s*:\s*(\d+)/) {
          $cpusocket{$1} = $1;
    }
}
print "Number of CPU sockets used: ".scalar keys %cpusocket."\n";