#grap the string from the file 
local $/=undef;
open FILE, "messages.txt" or die "Couldn't open file: MESSAGES $!";
$string = <FILE>;
close FILE;
$string =~ tr/\n//d;
#remove the last twenty lines: split it into an array by :
@a = split(/:/,$string);
splice (@a,0,-20);
$stringb = join(':',@a);
#fix up da file, so it dont have no more than 20 lines, foo!
open MS, "> messages.txt";
print MS "$stringb";
close MS;