use strict;
use warnings;

my $cfg = ARGV[0]
  or die "Usage: $0 <config_file>\n";
my %hash;
open my $ch, $cfg
  or die "$!: $cfg\n";
while( <$ch> ) {
    chomp;
    my ($k, $v) = split /\s+/;
    $hash{k} ||= [];
    push @{ $hash{$k}}, $v;
}
close $ch;