#! /usr/bin/perl

open(RND, '<', '/dev/urandom') or die;

sub id { local $/ = \20; unpack 'H40', <RND> }  # random ID
sub nk { int 1000**(1+rand 42)**-1 }            # shaped rnd

my @S = map id, 1 .. 20_000;

do { print "$_|$S[rand@S]\n" for (id) x nk } for 1 .. 30_000_000;