Why is topdir set to its default value when rpmbuild called from tcl?

Question

There’s two ways to change the default rpmbuild topdir:

Per-User: By configuring the RPM topdir in $HOME/.rpmmacros
```
%_topdir    %{getenv:HOME}/rpmbuild
```
Per-Project: By configuring the RPM topdir in the Makefile or on the command line
```
rpmbuild --define '_topdir build' -ba package.spec
```

Note: in both cases, you will need to make sure your topdir directory has the appropriate directories (BUILD, SRPM, RPM, SPECS and SOURCES)