You can use IPC::Run3 to redirect stdout to a perl data structure. Perhaps something like this might do the trick.

use IPC::Run3;
my @cmd = qw( /sbin/sfdisk -uM -q -L -O disksave --no-reread 
              /dev/hdz);
my ($in, $out, $err);
run3 \@cmd, \$in, \$out, \$err;
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