$ perl -v

This is perl 5, version 14, subversion 2 (v5.14.2) built for darwin-thread-multi-2level
...

$ uname -a
Darwin ganymede 11.4.2 Darwin Kernel Version 11.4.2: Thu Aug 23 16:25:48 PDT 2012; root:xnu-1699.32.7~1/RELEASE_X86_64 x86_64

##</code><code>##

$ cat pm_sh_escape.pl
#!/usr/bin/env perl

use strict;
use warnings;

my $cmd = "printf 'I\\x27ll'";
print $cmd . "\n";
print `$cmd` ."\n";

##</code><code>##

$ pm_sh_escape.pl
printf 'I\x27ll'
I'll

##</code><code>##

$ printf 'I\x27ll'
I'll