I've seen this as well. I edited my extension attribute like so:

#!/bin/sh

recoveryHDPresent=/usr/sbin/diskutil list | grep "Recovery HD"

if [ "$recoveryHDPresent" != "" ]; then
echo "<result>Present</result>"
else
echo "<result>Not Present</result>"
fi

Yup - I probably should have noticed that disk0 business too! :)

This works, thanks for your help!

For anyone who comes across this later, I found that the following worked on 10.11.4

#!/bin/sh



recoveryHDPresent='/usr/sbin/diskutil list | grep "Recovery HD"'



if [ "$recoveryHDPresent" != "" ]; then echo "<result>Present</result>"



else echo "<result>Not Present</result>"



fi

@dhanes You might want to edit your script to change the single quotes into backticks, or preferable command parenthesis. I.e, either

recoveryHDPresent=`/usr/sbin/diskutil list | grep "Recovery HD"`

or

recoveryHDPresent=$(/usr/sbin/diskutil list | grep "Recovery HD")

The way its posted right now, its not actually running a command. Its just a single quoted string.