use warnings;
use strict;

use JSON;

my %first_hash = (fruit => 'banana', Vegetable => 'tomato');
my %second_hash = (work => 'office', family => 'home');

my %hashes = (
    first_hash => \%first_hash,
    second_hash => \%second_hash,
);

my $json = encode_json \%hashes;

open my $fh, '>', 'data.json' or die $!;
print $fh $json;

##</code><code>##

{"second_hash":{"work":"office","family":"home"},"first_hash":{"Vegetable":"tomato","fruit":"banana"}}

##</code><code>##

use warnings;
use strict;

use Data::Dumper;
use JSON;

if (! @ARGV && ($ARGV[0] ne 'first_hash' || $ARGV[0] ne 'second_hash')){
    print "need first_hash or second_hash as arg\n";
    exit;
}

my $want = $ARGV[0];
my $file = 'data.json';

my $json;

{
    local $/;
    open my $fh, '<', $file or die $!;
    $json = <$fh>;
    close $fh;
}

my $data = decode_json $json;

print Dumper $data->{$want};

##</code><code>##

$ perl fetch_hash.pl first_hash

$VAR1 = {
          'fruit' => 'banana',
          'Vegetable' => 'tomato'
        };

$ perl fetch_hash.pl second_hash

$VAR1 = {
          'work' => 'office',
          'family' => 'home'
        };