#!/usr/bin/perl -w 

# usefull on a unix-like system
# this uses tail - displays the last lines in a file
# 'tail -n 4 filename' shows the last 4 lines in a file 

my $file_to_check = '/tmp/test_file.txt';
my $file_to_store = '/tmp/fill_this_file.txt';
my $pattern = 'special text';

while (1)
{
     my $last_line = `tail -n 1 $file_to_check`;
    if ($last_line =~ /$pattern/)
    {
        `tail -n 11 $file_to_check >> $file_to_store`;
    };
    sleep(30 * 60);
}
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