if (gr->gr_mem) for (i=0; gr->gr_mem[i]; i++)
if ((r = fprintf(f, "%s%s", i?",":"", gr->gr_mem[i]))<0) goto done;
r = fputc('\n', f);
if (gr->gr_mem) for (i=0; gr->gr_mem[i]; i++)
if ((r = fprintf(f, "%s%s", i?",":"", gr->gr_mem[i]))<0) goto done;
r = fputc('\n', f);