#!/usr/bin/perl -s

use strict;
our ($fs);
$fs ||= ":";

my $f1 = shift;
my $esq = shift or die("Usage: $0 filename schema\n");

my %c; @c{1..20}=(1..20);

my $b = `head -1 $f1`;
chomp $b;
my $n=0;

for (split(/\s*$fs\s*/,$b)){ $c{$_} = ++$n;}

my $cmps= join(",", map 
                 {$c{$_}?('$'. $c{$_}):(die("Error: no $_ field\n"))} 
                 split(/\s*$fs\s*/,$esq));

my $com = sprintf("awk '%s' $f1", "BEGIN {OFS=FS=\"$fs\"} {print $cmps}");

system "$com";