Adapted straight from the example in Text::CSV: 
use File::Copy qw(move);
use Text::CSV;

use strict;
use warnings;

my $csv = Text::CSV->new({binary => 1, eol => "\n"})
    or die "Cannot use CSV: ".Text::CSV->error_diag ();

my $oldfile = 'old.csv';
my $newfile = $oldfile . '.tmp';

open my $in, $oldfile or die "$oldfile: $!";
open my $out, '>', $newfile or die "$newfile: $!";

while (my $row = $csv->getline($in)) {
    splice @$row, 1, 0, "New Col 2";
    $csv->print($out, $row);
}

close $in;
close $out;

move($newfile, $oldfile) or die "Can't move: $!";

[download]

In reply to Re: adding a new column to a CSV by wind
in thread adding a new column to a CSV by Anonymous Monk

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.