This Perl script eats CR and LF characters embedded within quoted strings in a .csv file.

eat_CRLF_in_quoted_strs.pl

#!/usr/bin/env perl

# This Perl script eats CR and LF characters embedded within quoted strings in a .csv file.
# It assumes the file uses comma-separated values quoting rules:
# https://en.wikipedia.org/wiki/Comma-separated_values#Basic_rules
# and should work with any file, .csv or not, that follows them.

# TODO: Doesn't support double double-quotes embedded within the double-quoted strings.

# Args  <input file> 


use strict;
use warnings;

my ($file) = @ARGV;

# validate $file
if (not defined $file) {
	die "You need to provide a file to process.\n";
}

open (my $fh, "<", $file) or die "Can't open file: $!";

my $in_quoted_string = 0;
my $quote = '"';
my $lf = '\n';
my $cr = '\r';

my $char;

# read until the end of the file
until (eof($fh)) {

	# read a character
	$char = getc($fh);


	if ($in_quoted_string == 0) {
		# in pass-through mode, i.e., not within a quoted string

		if ($char eq $quote) {
			# character is the opening quote of a string; enter quoted-string mode
			$in_quoted_string = 1;
		}

	}

	else {
		# in quoted-string mode

		if ($char eq $quote) {
			# character is the closing quote; exit quoted-string mode
			$in_quoted_string = 0;
		}
		elsif ($char =~ /$lf|$cr/) {
			# character is an embedded line feed (LF) or carriage return (CR); eat it
			next;
		}

	}


	# write a character
	print $char;

}

close $fh || die "Couldn't close file properly!";