#!/usr/bin/perl
use strict;
use warnings;

my $fName = 'wibble.dat';
my $group;
open my $fIn, '<', $fName or die "Can't open $fName: $!\n";

while (my @lines = scanFile($fIn)) {
    report(++$group, @lines);
}


sub scanFile {
    my ($fIn) = @_;
    my @lines;
    
    while (@lines < 10 && defined (my $line = <$fIn>)) {
        chomp $line;
        next if ! length $line;
        push @lines, $line;
    }

    return @lines;
}


sub report {
    my ($group, @lines) = @_;
    
    printf "%04d: %s\n", $group for @lines;
}