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 = ['apt-transport-https', 'ca-certificates',
                                     'gnupg', 'man-db', 'openssh-client',
                                     'wget']

            self.__bashrc = '/etc/bash.bashrc'

        elif hpccm.config.g_linux_distro == linux_distro.CENTOS:
            if not self.__ospackages:
                self.__ospackages = ['man-db', 'openssh-clients']

            self.__bashrc = '/etc/bashrc'

        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/intel_mpi.py