Thanks for the suggestion

    open($file_read,"+<","$file") or croak "cant open $file for read";
    flock($file_read,2);
    my $count=<$file_read>;
    $count++;
    seek($file_read, 0, "0");
    print $file_read $count;
    flock($file_read,8);
    close($file_read);
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