#!/usr/bin/perl

use strict;
use warnings;

my $text = join '', (<DATA>);
my @match = $text =~ /^10.*\r?\n20.*\r?\n01.*$/mg;
s/\r?\n/---/g and print for @match;

__DATA__
01|1-123-878|Musterfrau
01|1-010-123|Muster
01|1-051-543|Mayer
20|2-123-452|Bauer
01|2-453-345|Huber
10|1-123-134|Max Mustermann
20|1-456-789|Peter Huber
01|1-457-123|Max Mayer