my $reportfile = '/home/user/data.txt';
open my $reports, "<", $reportfile
  or die "Could not read '$reportfile': $!";

my @knowntypes = qw(1 2 3 4 5);
my %filehandle;
for my $type (@knowntypes) {
  open $filehandle{$type}, ">>", "form_${type}_record.txt"
    or die "Couldn't create 'form_$type_record.txt': $!";
};
for (<$reports>) {
  /^(\d+)\|/
    or die "Malformed input line: $_";
  my $type = $1;
  if (not exists $filehandle{$type}) {
    die "Unknown record type $type in line $_";
  };
  print $filehandle{$type} $_;
};