#!/usr/bin/perl
use warnings;
use strict;

# process headers, create filehandles
my @fhs;
for my $header ( split ' ', <DATA> ) {
    my $file = "$header.dat";
    open my $FH, '>', $file or die "Cannot open '$file' $!";
    push @fhs, $FH;
    }

while ( <DATA> ) {
    my @fields = /\S+\s+\S+/g;
    @fields == @fhs or die "Error: incorrect number of fields in recor
+d $.\n";
    for my $fh ( @fhs ) {
        print $fh shift( @fields ), "\n";
        }
    }


__DATA__
item1 item2 item3  
0  0    1  S    0  0   
0  0    2  K    0  0   
0  0   23  T    1  M
12 T   24  N    2  L 
45 0   36  V   14  I 
46 0   38  W   16  R 
51 S   39  A   17  L
52 A   42  N   20  E
53 0   43  L   21  G
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