Create global variable or variable user/group rpm - global-variables

Question

I have a problem. Depending on the plattform my files in the rpm have different users/groups.
The problem is you already shoud see the right attributes of the rpm with rpm -V so I can't change the Attributes in the %post section because this will always show the user has been changed.
Is there a way to create a global variable where I set the name of the variable user and then use it in the %files section?
I tried it with define but it does not work right:
%pre
HOME = path
if[true]
%define USER example1
useradd -m -r -c $HOME $USER
else
%define USER example2
useradd -m -r -c $HOME $USER
fi
%files
%defattr(-, %{USER}, ...)
This gives me the error warning: user example2 does not exist - using root
Does anyone know how to solve this problem?

Answer 1

%files is evaluated and installed before %post is executed. The user must exist in advance. Therefore:
At very top of spec file puth
%global USERNAME example1
%global GROUPNAME example1
and then in %pre put:
%pre
getent group %{GROUPNAME} >/dev/null || groupadd -r %{GROUPNAME}
getent passwd %{USERNAME} >/dev/null || \
useradd -r -g %{GROUPNAME} -d HOMEDIR -s /sbin/nologin \
-c "Useful comment about the purpose of this account" %{USERNAME}
exit 0
For more information see:
https://fedoraproject.org/wiki/Packaging:UsersAndGroups?rd=Packaging/UsersAndGroups#Dynamic_allocation

Answer 2

I pretty sure that this is not best practice but I found a way:
%build
if [condition]; then
%global USERNAME example1
else
%global USERNAME example2
fi
And later in the %pre section I can add the user, in case he does not exists.
Then I can use this variable user in the files section just as in my question with %attr(-, %{USERNAME}, ...)
If I would define the global variable at the beginning of the file
(%global USERNAME example0), the build would simply use the value defined there and ignore the changed values in the %build.