What's inside a mystery software package file?
27 March 2019
A package (.pkg file in OS X) is an .xar archive containing a cpio.gz archive of installable files in "Payload", along with a "bill of materials", scripts, etc. To inspect the contents, unpack the .xar into a directory, and then open the Payload file:
mkdir scratch; cd scratch xar -xf ../mystery.pkg gunzip -dc Payload | cpio -i
The file hierarchy shows where the contents of the package would be distributed during installation.