def __distro(self):
        """Based on the Linux distribution, set values accordingly.  A user
        specified value overrides any defaults."""

        if hpccm.config.g_linux_distro == linux_distro.UBUNTU:
            if not self.__ospackages:
                self.__ospackages = ['file', 'hwloc', 'libevent-dev', 'make',
                                     'tar', 'wget']
                if self.__check:
                    self.__ospackages.append('perl')
            self.__runtime_ospackages = ['libevent-2.*',
                                         'libevent-pthreads-2.*']
        elif hpccm.config.g_linux_distro == linux_distro.CENTOS:
            if not self.__ospackages:
                self.__ospackages = ['file', 'hwloc', 'libevent-devel', 'make',
                                     'tar', 'wget']
                if self.__check:
                    self.__ospackages.append('perl')
            self.__runtime_ospackages = ['libevent']
        else: # pragma: no cover
            raise RuntimeError('Unknown Linux distribution')
Based on the Linux distribution, set values accordingly.  A user
        specified value overrides any defaults.
hpccm/building_blocks/pmix.py