$ cat test.pl
#!/pro/bin/perl

use 5.012003;
use warnings;

use Text::CSV_XS qw( csv );

my $aoh = csv (in => *DATA, kh => \my @h);
say "Head was (@h)";

# Construct new header (out of old header)
my @nh = qw( column2 column1 column4 column3 );
csv (in => $aoh, headers => \@nh);

__END__
column1,column2,column3,column4,column5,column6
datar1c1,datar1c2,datar1c3,datar1c4,datar1c5,datar1c6
datar2c1,"data,r2c2",datar2c3,datar2c4,datar2c5,datar2c6
datar3c1,datar3c2,"data, r3c3",datar3c4,datar3c5,datar3c6

##</code><code>##

$ perl test.pl
Head was (column1 column2 column3 column4 column5 column6)
column2,column1,column4,column3
datar1c2,datar1c1,datar1c4,datar1c3
"data,r2c2",datar2c1,datar2c4,datar2c3
datar3c2,datar3c1,datar3c4,"data, r3c3"