You can determine the PMK (Port Machine Key) for a Unix/Linux Acu/Extend product by requesting extended version information. This can be done using the -vvv flag with the runcobol command, as described here:

https://community.rocketsoftware.com/discussion/runtime-identifying-the-version-of-the-runtime-being-used#bm09b85089-ff36-442a-81ca-50b7237834e3

When runcbl -vvv is executed, one of the pieces of information displayed is the PMK. For example: port_machine_key='59'.

Another option that can work is to execute the following command from the bin directory beneath the Acu/Extend product installation:

cat ../lib/Makefile | grep PMK