my $log_file = $ARGV[0] || 'log.file';
open(my $fh, '<', $log_file) or die "Unable to open '$log_file' for reading: $!";
my %name;
while (<$fh>) {
    chomp;
    my ($fn, $ln, $rest) = $_ =~ /^(\w+)\s+(\w+)(.*)/;
    $name{$ln} = "$ln $fn$rest\n";
}
for (sort keys %name) {
    print "$name{$_}";
}