#!/usr/bin/perl
use warnings;
use strict;
use Inline::Files;

my %File1Hash;

while (my $line = <FILE1>)
{
    next if $line =~ /^\s*$/;  # skip blank lines
    $line =~ s/\s*$//; # remove all trailing space,
                       # including the line ending

    $File1Hash{$line}++;
}

while (my $line = <FILE2>)
{
    next if $line =~ /^\s*$/;  # skip blank lines
   
    my ($id) = split /\|/,$line;  # get the first field
    print $line if exists $File1Hash{$id};
}

=Prints
COA213345|a|b|c|
COA213345|a|b|c|
=cut

__FILE1__
COA213345
COA213345
COA213445
DOB213345
EOA213345

__FILE2__
COA213345|a|b|c|
COA213345|a|b|c|
LOA213345|a|b|c|
kOB213345|a|b|c|
LOA213345|a|b|c|