RPM packaging

NUM_RPM_INSTANCE == 1 is a normal installation

NUM_RPM_INSTANCE == 2 is a normal upgrading

NUM_RPM_INSTANCE == 0 is a normal uninstallation

Here are the actual values passed during an install:

Run %pre of new package (1)
Install new files
Run %post of new package (1)

Here are the values passed during an upgrade:

Run %pre of new package (2)
Install new files
Run %post of new package (2)
Run %preun of old package (1)
Delete any old files not overwritten by newer ones
Run %postun of old package (1)

Here are the values passed during a delete:

Run %preun of old package (0)
Delete files
Run %postun of old package (0)