#!/usr/bin/perl

my @normal_rows = (2..66); 
my $i;
my @rows_to_remove = ();
my $cmd;

# pick all but 25 rows to remove
for($i=0; $i<(65 - 25); $i++){
    push @rows_to_remove, splice(@normal_rows, int rand @normal_rows, 1);
}

my $nrows = scalar(@rows_to_remove);
print "num rows to be removed: $nrows\n";

my $str_rm = "";
foreach my $num (@rows_to_remove){ 
    print ">>> will remove row $num\n"; 
    $str_rm = $str_rm."$num"."d;";
}

$cmd = "sed --in-place '$str_rm' *txt";
print "$cmd\n";
system($cmd);