Joseph Herlant
version 1.0.0, 2014-07-07 : Initial version
The directory structure needed for a RPM is:

  • SOURCES → Source code of the package to build

  • SPECS → Spec file(s) (one per RPM)

  • BUILD → Compilation space

  • tmp → A temporarybuild directory

  • RPMS → Final binary RPM(s) will be located there

  • SRPMS → Final source RPM(s) will be located there

In the following example, we are using a basic C file that prints "Hello world!". The name of our package will be "dummy_package" and the provided binary output will be "hello_world". So as prerequisites, we create the C file in a temporary FS and create a tarball with it:

PKG_NAME=dummy_package
PKG_DIR=/tmp/${PKG_NAME}
mkdir -p ${PKG_DIR}

cat << __EOF__ > ${PKG_DIR}/hello_world.c
#include <stdio.h>
int main(){
  printf("Hello world!\n");
  return 0;
}
__EOF__

pushd ${PKG_DIR}/..
tar czvf ${PKG_NAME}.tar.gz ${PKG_NAME}
popd

Here is the script that generates your sample SPEC/dummy_package.spec file and builds the package:

#!/bin/sh
# This scripts creates and build a simple RPM package
#
# Prerequisites:
#  - rpm-build, make and gcc (as it's a c file) packages must be installed
#

# Holds the name of the root directory containing the necessary structure to
# build RPM packages.
RPM_ROOT_DIR=~/rpm_factory
PKG_NAME=dummy_package
PKG_TAR=/tmp/${PKG_NAME}.tar.gz
BINARY_FILE=hello_world
# Recreate the root directory and its structure if necessary
mkdir -p ${RPM_ROOT_DIR}/{SOURCES,BUILD,RPMS,SPECS,SRPMS,tmp}
pushd  $RPM_ROOT_DIR
cp ${PKG_TAR} ${RPM_ROOT_DIR}/SOURCES/

# Creating a basic spec file
cat << __EOF__ > ${RPM_ROOT_DIR}/SPECS/${PKG_NAME}.spec
Summary: This package is a sample for quickly build dummy RPM package.
Name: $PKG_NAME
Version: 1.0
Release: 0
License: GPL
Packager: $USER
Group: Development/Tools
Source: %{name}.tar.gz
BuildRequires: coreutils
BuildRoot: ${RPM_ROOT_DIR}/tmp/%{name}-%{version}

%description
%{summary}

%prep
%setup -n ${PKG_NAME}

%build
make $BINARY_FILE

%install
mkdir -p "%{buildroot}/opt/${PKG_NAME}"
cp $BINARY_FILE "%{buildroot}/opt/${PKG_NAME}/"

%files
/opt/${PKG_NAME}/hello_world

%clean
%if "%{clean}" != ""
  rm -rf %{_topdir}/BUILD/%{name}
  [ $(basename %{buildroot}) == "%{name}-%{version}-%{release}.%{_target_cpu}" ] && rm -rf %{buildroot}
%endif

%post
chmod 755 -R /opt/${PKG_NAME}
__EOF__

rpmbuild -v -bb --define "_topdir ${RPM_ROOT_DIR}" SPECS/${PKG_NAME}.spec
popd

Now play with the package. For example:

sudo rpm -ivh ~/rpm_factory/RPMS/x86_64/dummy_package-1.0-0.x86_64.rpm
rpm -ql dummy_package
/opt/dummy_package/hello_world
sudo rpm -e dummy_package