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

use Text::CSV_XS qw{ csv };

csv(in     => shift,
    eol    => "\n",
    filter => {1 => sub { length },
               5 => sub { length }});
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It will only keep the lines where columns 1 and 5 (1-based) have a non-zero length.

Tested on:

1,2,3,4,5,6
keep,keep,keep,keep,keep,keep
,delete,delete,delete,delete,delete
keep,,,,keep,
delete,delete,delete,delete,,delete
keep,2,3,4,keep,6
,delete,delete,delete,,delete
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($q=q:Sq=~/;[c](.)(.)/;chr(-||-|5+lengthSq)`"S|oS2"`map{chr |+ord
}map{substrSq`S_+|`|}3E|-|`7**2-3:)=~y+S|`+$1,++print+eval$q,q,a,
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