storehash.pl

#!/usr/bin/perl

use strict;
use warnings;
use feature 'say';
use Storable;

my $hashref;
my $hash_file = 'hashfile';

if (-e $hash_file) {
  $hashref = retrieve($hash_file);
} else {
  $hashref = {};
}

if (@ARGV == 2) {
  my ($newkey, $newval) = @ARGV;
  $hashref->{$newkey} = $newval;
}

say "$_ -> $hashref->{$_}" for sort keys %$hashref;

store $hashref, $hash_file;

Pass two values to this program (a key and a value) to add a key/value pair to the persistent hash.

Don't pass any data to the program to just get a dump of the current data in the persistent hash.