use File::Temp qw/tempfile/;
my ($fh,$fn) = tempfile(UNLINK=>1);
print $fh $output;
close $fh;
system('less',$fn) == 0 or die "system: \$?=$?";

##</code><code>##

use IPC::Run3 'run3';
run3 ['less'], \$output or die $!;
die "run3: \$?=$?" if $?;

##</code><code>##

my @cmd = ('less', '-');
die '@cmd must have more than one element' unless @cmd>1;
open my $fh, '|-', @cmd or die $!;
print $fh $output;
close $fh or die $! ? $! : "pipe: \$?=$?";