How does rpmbuild move the results to the target - linux

Question

When I do
rpmbuild -bi ~/rpmbuild/SPECS/microemacs.spec
The result is
>g++ -g -I. -I../src basic.o bind.o buffer.o char.o crypt.o display.o eval.o exec.o file.o
> fileio.o input.o isearch.o line.o main.o malloc.o mouse.o msdir.o random.o region.o search.o
> sinc.o tag.o window.o word.o map.o unix.o terminal.o lock.o -o microemacs
>
>+ exit 0
> Executing(%install): /bin/sh -e /var/tmp/rpm-tmp.dzYbvW
> + umask 022
> + cd /home/<redacted>/rpmbuild/BUILD
> + '[' /home/<redacted>/rpmbuild/BUILDROOT/microemacs-2.9-0.x86_64 '!=' / ']'
> + rm -rf /home/<redacted>/rpmbuild/BUILDROOT/microemacs-2.9-0.x86_64
> ++ dirname /home/<redacted>/rpmbuild/BUILDROOT/microemacs-2.9-0.x86_64
> + mkdir -p /home/<redacted>/rpmbuild/BUILDROOT
> + mkdir /home/<redacted>/rpmbuild/BUILDROOT/microemacs-2.9-0.x86_64
> + cd microemacs-2.9
> + echo /home/<redacted>/rpmbuild/BUILD/unix
> /home/<redacted>/rpmbuild/BUILD/unix
> + cd /home/<redacted>/rpmbuild/BUILD/microemacs-2.9
> + cd unix
> + cp microemacs /home/<redacted>/rpmbuild/BUILDROOT/microemacs-2.9-0.x86_64/
> + cp ../macros/.emacsrc /home/<redacted>/rpmbuild/BUILDROOT/microemacs-2.9-0.x86_64/
> + cp ../src/microemacs.md /home/<redacted>/rpmbuild/BUILDROOT/microemacs-2.9-0.x86_64/
> + /usr/lib/rpm/find-debuginfo.sh --strict-build-id -m --run-dwz --dwz-low-mem-die-limit 10000000 --dwz-max-die-limit 110000000 /home/smit_pet/rpmbuild/BUILD/microemacs-2.9
> extracting debug info from /home/smit_pet/rpmbuild/BUILDROOT/microemacs-2.9-0.x86_64/microemacs
> dwz: Too few files for multifile optimization
> /usr/lib/rpm/sepdebugcrcfix: Updated 1 CRC32s, 0 CRC32s did match.
> 1019 blocks
> + /usr/lib/rpm/check-buildroot
> + /usr/lib/rpm/redhat/brp-compress
> + /usr/lib/rpm/redhat/brp-strip-static-archive /usr/bin/strip
> + /usr/lib/rpm/brp-python-bytecompile /usr/bin/python 1
> + /usr/lib/rpm/redhat/brp-python-hardlink
> + /usr/lib/rpm/redhat/brp-java-repack-jars
> Processing files: microemacs-2.9-0.x86_64
> error: File must begin with "/": microemacs
> error: File must begin with "/": .emacsrc
> error: File must begin with "/": microemacs.md
>
> RPM build errors:
> File must begin with "/": microemacs
> File must begin with "/": .emacsrc
> File must begin with "/": microemacs.md
I do not understand how the distinction between BUILD BUILDROOT or how the results get to the target and how %file features in this.
Also why the /usr/lib action and why and how is this happening?
I want the results to end up in ~/bin/ and I can do this with a manual copy in %install but I think this is not the correct way.
Also nothing prints Hello.
The .spec file is
> SPECS/microemacs.spec
> Name: microemacs
> %define version 2.9
> Version: %{version}
> Release: 0
> Summary: Microemacs program code editor
> Group: Applications/Development
> License: GPL 3.0 License
> URL: .
> Vendor: .
> Source: microemacs-%{version}.tar.gz
> Prefix: %{_prefix}
> Packager: .
> BuildRoot: %{_tmppath}/%{name}-root
>
> %description
> A text editor suporting
> + Piping input into it.
> + Editting Directories and their contents.
> + Taking text from the buffer into the command line
>
> %prep
>
> %setup -q
>
> %build
> echo Hello
> pwd
> cd ./unix
> make
>
> %install
> echo %{_builddir}/unix
> cd %{_builddir}/microemacs-%{version}
> cd unix
> cp microemacs %{buildroot}/
> cp ../macros/.emacsrc %{buildroot}/
> cp ../src/microemacs.md %{buildroot}/
>
> %clean
> cd ${_builddir}/microemacs-%{version}/unix
> make clean
>
> %files
> %defattr(-,root,root)
> microemacs
> .emacsrc
> microemacs.md

Answer 1

The %buildroot during the %install phase is directory where you create the layout of target. I.e., how it will be stored in final rpm.
When you have:
%install
cp microemacs %{buildroot}/
then you have to have
%files
/microemacs
But you likely want to have:
%install
cp -a microemacs %{buildroot}%{_bindir}/microemacs
%files
%{_bindir}/microemacs
%doc microemacs.md
This will place the microemacs to /usr/bin and microemacs.md to /usr/share/doc - no need to cp microemacs.md there during %install as the %doc macro will take care of it.