use warnings;
use strict;
use Data::Dumper;

my $message_log = "/var/log/messages";

my %messages = (
        error   => {},
        alert   => {},
        warning => {},
);

open(my $logfile, "<", $message_log)
        or die "Unable to open $message_log: $!\n";
foreach my $type (keys(%messages)) {
        seek $logfile, 0, 0;
        foreach my $line (<$logfile>) {
                $messages{$type} .= $line if($line =~ /$type/);
        }
}
close($logfile);

print Dumper(\%messages);