# in-memory files
21. open(my $memory, ">", \$var)
22.     or die "Can't open memory file: $!";
23. print $memory "foo!\n";              # output will appear in $var

##</code><code>##

#!/usr/bin/perl
use strict;
use warnings;

my $file = 'here
are
some
words
I
want
';

open my $fh, '<', \$file;

chomp(my @words = <$fh>);

my $pattern = join "|", @words;

print $pattern;