my @aColumns1;
my @aColumns2;

open ( my $sData, '<', $hFile ) or die "Could not open '$hFile' $!\n";
while ( my $sLine = <$sData> ) 
{
  chomp $sLine;
  my @aFields = split "," , $sLine;
  push ( @aColumns1, $aField[1] );
  push ( @aColumns2, $aField[3] );
}
close ( $hFile );

my @aColumns3;
my @aColumns4;
@aFields = '';

open ( $sData, '<', $hFile ) or die "Could not open '$hFile' $!\n";
while ( $sLine = <$sData> ) 
{
  chomp $sLine;
  @aFields = split "," , $sLine;
  push ( @aColumns3, $aField[2] );
  push ( @aColumns4, $aField[4] );
}
close ( $hFile );

open ( '>', $hFile ) or die "Could not open '$hFile' $!\n";
for (...)
{
	print $hFile "$aColumns1[x];$aColumns2[x];$aColumns3[x];$aColumns4[x]\n";
}
close ( $hFile );