Create macOS Sierra Recovery Partition Without Reinstalling

recovery.sh

TARGET="/Volumes/Macintosh HD"                                  # Specify where to configure Recovery partition
MACOS_INSTALLER="/Applications/Install\ macOS\ Sierra.app"      # Path to your macOS installer

# Remaining paths ahead are dependant on OS version
# This *should* support 10.9 and above but is only tested on 10.12

curl http://support.apple.com/downloads/DL1464/en_US/RecoveryHDUpdate.dmg -L -o ~/Downloads/RecoveryHDUpdate.dmg
hdiutil mount ~/Downloads/RecoveryHDUpdate.dmg
pkgutil --expand /Volumes/Mac\ OS\ X\ Lion\ Recovery\ HD\ Update/RecoveryHDUpdate.pkg /tmp/recoveryupdate

hdiutil mount "$MACOS_INSTALLER/Contents/SharedSupport/InstallESD.dmg"
/tmp/recoveryupdate/RecoveryHDUpdate.pkg/Scripts/Tools/dmtest ensureRecoveryPartition "$TARGET" "/Volumes/OS X Install ESD/BaseSystem.dmg" 0 0 "/Volumes/OS X Install ESD/BaseSystem.chunklist"
hdiutil eject "/Volumes/Mac OS X Lion Recovery HD Update"/
hdiutil eject "/Volumes/OS X Install ESD"/