








         Differences between B 2.11 news and C news


                       Geoff Collyer

                  Department of Statistics
                   University of Toronto





_I_n_t_r_o_d_u_c_t_i_o_n

     This document attempts to describe  the  major  differ-
ences  between  B 2.11 news and C news; it cannot pretend to
be complete.  Since the message format of both  is  the  one
described  in  ARPA Internet RFC 1036, the differences arise
primarily in how the software is set up and administered.

     C news was begun before B 2.11 news was  released,  and
later  updated  to  match  the  worthwhile changes in B 2.11
news.

_D_i_f_f_e_r_e_n_c_e_s _i_n _f_i_l_e_s

     _L_o_c_k_i_n_g.  C news locks are intended  to  be  compatible
with  those  of  B  2.10  news.  C news locks out _e_x_p_i_r_e and
_r_n_e_w_s by linking to the name /_u_s_r/_l_i_b/_n_e_w_s/_L_O_C_K and  repeat-
ing  until  successful; there is no time-out such as the one
in B 2.10 news, so humans can lock the news system and  per-
form surgery on it with confidence.  B 2.11 news is believed
to  use  more  modern  kernel  locking  facilities  such  as
_f_l_o_c_k(2)  and  _l_o_c_k_f(2).  One important difference is that C
news's locks will work across network file  systems,  modulo
problems caused by lock removal in /_e_t_c/_r_c.

     _L_o_g _f_i_l_e_s.  C news's are terse.

     _H_i_s_t_o_r_y _f_i_l_e.  C news uses an extended B 2.10 news for-
mat: the second field consists of two subfields separated by
a tilde: time received as an integer (a _t_i_m_e__t in fact), and
the  value of the _E_x_p_i_r_e_s: header, "-" if none.  B 2.11 news
does not record the  _E_x_p_i_r_e_s:  value  and  stores  the  time
received  in  a  peculiar  variant of _c_t_i_m_e(3) format, which
cannot be parsed by _g_e_t_d_a_t_e(3), to the  annoyance  of  _n_n_t_p.
You  must  lock the news system with _l_o_c_k_n_e_w_s before editing
the history file.

     _a_c_t_i_v_e _f_i_l_e.  C news will tolerate two, three, or  four
fields  in  the _a_c_t_i_v_e file, and any number of digits in the



                       March 26, 1991





                           - 2 -


article-number fields (hint: five is too few).  C news  also
supports  two  new  values  for the fourth field: _x, meaning
``quietly discard articles for this group'', and  =realgroup
meaning  ``file  articles  for  this  group  under _r_e_a_l_g_r_o_u_p
instead''.  = is useful  for  coping  with  badly-run  local
newsgroups, often created from mailing lists.  You must lock
the news system with  _l_o_c_k_n_e_w_s  before  editing  the  active
file.

     _s_y_s _f_i_l_e.  C news ignores blank  lines  and  #  comment
lines in the _s_y_s file.  Many obsolete flags draw fatal diag-
nostics, notably _N, the old,  unbatched  ihave/sendme  flag.
If   the   fourth   field   is   a  relative  command  name,
/_u_s_r/_l_i_b/_n_e_w_s/_b_i_n   and   /_u_s_r/_l_i_b/_n_e_w_s_b_i_n/_r_e_l_a_y   will   be
searched  before  the  standard  search path.  If the fourth
field is a  relative  file  name,  /_u_s_r/_s_p_o_o_l/_n_e_w_s/_o_u_t._g_o_i_n_g
will  be prepended.  The ihave/sendme kludges of B news have
been expunged; one must say what one means, using  three  to
five entries, typically.

_D_i_f_f_e_r_e_n_c_e_s _i_n _b_e_h_a_v_i_o_u_r

     _C_o_n_t_r_o_l _m_e_s_s_a_g_e_s.  _C_h_e_c_k_g_r_o_u_p_s is non-destructive in  C
news;  it  merely  mails  its  output  to  $_N_E_W_S_M_A_S_T_E_R (e.g.
_u_s_e_n_e_t).  C news adds  an  _A_l_s_o-_C_o_n_t_r_o_l:  header,  of  which
_S_u_p_e_r_s_e_d_e_s: is a special case.

     _N_e_w_s_g_r_o_u_p _a_l_i_a_s_e_s.  C news does not implement newsgroup
aliases,  since  we  believe  that  header  munging is to be
avoided except under extreme duress.  It is possible to file
articles  locally  under  different newsgroups by use of the
active file = flag.

























                       March 26, 1991


