def runtime(self, _from='0'):
        """Generate the set of instructions to install the runtime specific
        components from a build in a previous stage.

        # Examples

        ```python
        g = gnu(...)
        Stage0 += g
        Stage1 += g.runtime()
        ```
        """
        self.rt += comment('GNU compiler runtime')
        if self.__source:
            self.rt += copy(_from=_from,
                            dest=posixpath.join(self.prefix, 'lib64'),
                            src=posixpath.join(self.prefix, 'lib64'))
            if self.ldconfig:
                self.rt += shell(commands=[self.ldcache_step(
                    directory=posixpath.join(self.prefix, 'lib64'))])
            else:
                self.rt += environment(variables=self.environment_step(
                    include_only=['LD_LIBRARY_PATH']))
        else:
            self.rt += packages(
                apt=self.__runtime_debs,
                apt_ppas=self.__extra_repo_apt,
                release_stream=bool(self.__version), # True / False
                scl=bool(self.__version), # True / False
                yum=self.__runtime_rpms)

        return str(self.rt)
Generate the set of instructions to install the runtime specific
        components from a build in a previous stage.

        # Examples

        ```python
        g = gnu(...)
        Stage0 += g
        Stage1 += g.runtime()
        ```
        
hpccm/building_blocks/gnu.py