BASH: Create Bootable ISO from OSX Installer Package

hdiutil attach /Applications/Install\ OS\ X\ El\ Capitan.app/Contents/SharedSupport/InstallESD.dmg -noverify -nobrowse -mountpoint /Volumes/install_app

hdiutil convert /Volumes/install_app/BaseSystem.dmg -format UDSP -o /tmp/El\ Capitan

hdiutil resize -size 9g /tmp/El\ Capitan.sparseimage

hdiutil attach /tmp/El\ Capitan.sparseimage -noverify -nobrowse -mountpoint /Volumes/install_build

rm /Volumes/install_build/System/Installation/Packages

cp -rp /Volumes/install_app/Packages /Volumes/install_build/System/Installation/

cp -rp /Volumes/install_app/BaseSystem.chunklist /Volumes/install_build

cp -rp /Volumes/install_app/BaseSystem.dmg /Volumes/install_build

hdiutil detach /Volumes/install_app

hdiutil detach /Volumes/install_build

hdiutil resize -size `hdiutil resize -limits /tmp/El\ Capitan.sparseimage | tail -n 1 | awk '{ print $1 }'`b /tmp/El\ Capitan.sparseimage

hdiutil convert /tmp/El\ Capitan.sparseimage -format UDTO -o /tmp/El\ Capitan

rm /tmp/El\ Capitan.sparseimage

mv /tmp/El\ Capitan.cdr ~/Desktop/El\ Capitan.iso

sudo drutil burn ~/Desktop/El\ Capitan.iso