use Path::Class qw(file);
use Text::CSV;

my $input  = \*STDIN;
my $output = \*STDOUT;
# ... or use open() to open file handles

my $csv = Text::CSV->new({allow_whitespace => 1, eol => "\n"});
while (my $row = $csv->getline($input))
{
	$row->[4] = file($row->[4])->basename;
	pop @$row until $row->[-1];
	$csv->print($output, $row);
}