@keric The following is largely untested as I don't find a match for "color" in my output for system_profiler SPDisplaysDataType, so I searched for the display's serial number. Change "Display Serial Number" to your search term. (Remove set -x and set +x when you're done testing.) As always, YMMV.

#!/bin/bash



####################################################################

# An Extension Attribute to detect external display serial number. #

# If not applicable, "Not Applicable" will be returned.            #

####################################################################



set -x



RESULT="Not Applicable"



displayTypeData=$( /usr/sbin/system_profiler SPDisplaysDataType )



displaySerialNumber=$( /bin/echo ${displayTypeData} | /usr/bin/grep "Display Serial Number" | /usr/bin/awk -F ': ' '{print $NF}' )



if [[ -n "${displaySerialNumber}" ]]; then

    RESULT=${displaySerialNumber}

fi



echo "<result>$RESULT</result>"



set +x



exit 0

@dan-snelson Thanks so much had to change a few things this is what I ended up with using.

#!/bin/zsh



####################################################################

# An Extension Attribute to detect external display dongle. #

# If not present, "No" will be returned.#

####################################################################



RESULT="No"



displayTypeData=$( /usr/sbin/system_profiler SPDisplaysDataType | /usr/bin/grep "fit" )



displayinfo=$( /bin/echo ${displayTypeData} )



if [[ -n "${displayinfo}" ]]; then

    RESULT="Yes"

fi



echo "<result>$RESULT</result>"



exit 0