tliang.pl

#!/usr/bin/env perl

use strict;
use warnings;

my $log = $ARGV[0] || 'log.txt';

while (1) {
    my $line_number = (split q{ }, `wc -l $log`)[0];
    my $tail = `tail $log`;
    print "$line_number\n$tail\n";
    sleep 10;
}