How to extract contents from 'Payload' file in a apple macOS update package?

Question

I am extracting macOS sierra update package - macOSUpd10.12.1.pkg using following command to /tmp/macosupd directory.

pkgutil --expand /Volumes/         


        

Answer 1

Since OSX 10.10, the Payload in the .pkg files is encoded as pbzx (which is in turn lzma compressed). It can no longer be extracted using gunzip. Check out the pbzx tool (a fork of the original which would not allow you to extract the Payload directly but only by passing the .pkg file directly).

Instead of

tar -xvf macOSUpd10.12.1.pkg/Payload 

you can write

pbzx -n macOSUpd10.12.1.pkg/Payload | cpio -i

Answer 2

There is an undocumented option to pkgutil, --expand-full, which uses the same syntax as pkgutil --expand.

pkgutil --expand-full [pkg] [dir]

This will completely "unarchive" a pkg or mpkg file.