#! perl -sw
use strict;

my $count=1;
my $regex = qr/$count/;
my $told = tell DATA;
my $line;
for $count (1 .. 10) {
    $line =~ $regex and print $line while $line = <DATA>;
    seek DATA, $told, 0;
}

__DATA__
line 1
line 2
line 3
line 4
line 5
line 6
line 7
line 8
line 9