ppaatthhss -- System Administration

Routing data base for mail
/uussrr/lliibb/mmaaiill/ppaatthhss

File  /uussrr/lliibb/mmaaiill/ppaatthhss holds  the data  base used  by the  COHERENT mail
system to route  mail.  Each line gives routing information  to a host, and
has the following format:

    host    route   [cost]

_h_o_s_t names a UUCP host.   Because ssmmaaiill uses a binary-search algorithm when
searching the data  base for a given host name,  the lines in ppaatthhss must be
sorted  into  ascending order.   (See  the Lexicon  entry  for bbsseeaarrcchh  for
details on binary searches.) ssmmaaiill  ignores case when it searches ppaatthhss, so
you should convert each host name to lower case before you sort ppaatthhss.

The _r_o_u_t_e field details the route by which mail can travel from your system
to _h_o_s_t. Note that it includes a pprriinnttff-style format string.

The  optional field  _c_o_s_t is  used by  the COHERENT  mail system  to decide
whether to  queue outbound UUCP  mail, or to  invoke uuuucciiccoo to  deliver the
mail  immediately.   If  the   _c_o_s_t  is  at  or  below  ssmmaaiill's  ``queueing
threshold'',  then ssmmaaiill  will  attempt to  deliver  it immediately.   This
speeds mail  delivery between  hosts that  enjoy an inexpensive  UUCP link,
such  as  a hard-wired  line,  and  batches mail  that  must  be sent  over
expensive media,  such as  long-distance telephone.   If the _c_o_s_t  field is
absent,  ssmmaaiill gives  this host  a cost  value above  that of  its queueing
threshold.

_E_x_a_m_p_l_e
The following  gives a  sample ppaatthhss  file for a  COHERENT system  that its
owner has named lleeppaannttoo.

     friend       friend!%s   300
     hubsys       hubsys!%s   95
     lepanto      %s          0
     lepanto.ampr.org         %s0
     smart-host   hubsys!%s   95
     widget       hubsys!widget!%s95

As this  file shows, lleeppaannttoo  is linked to  systems hhuubbssyyss and  ffrriieenndd. The
cost of 95 associated with hhuubbssyyss  is low, and is appropriate to a low-cost
link,  such as  a  hard-wired link;  On  the other  hand, the  cost of  300
associated with  ffrriieenndd is high,  which indicates that  the connection with
ffrriieenndd is high-cost, such as a long-distance telephone connection.  If cost
is 100  or greater, mail will  be queued for later  delivery.  A cost below
100 tells ssmmaaiill to attempt immediate delivery.

In  this example,  machine lleeppaannttoo  is registered  in the  aammpprr.oorrgg Amateur
Packet  Radio  domain.  Note  that  machine name  lleeppaannttoo  appears in  both
conventional and domain forms in order to help resolve addressing.

In order to avoid having to maintain a huge data base, the owner of lleeppaannttoo
uses hhuubbssyyss as  a _s_m_a_r_t _h_o_s_t. The ssmmaarrtt-hhoosstt designation  in the ppaatthhss data
base signals ssmmaaiill to forward any  mail that it doesn't know how to deliver
onto site hhuubbssyyss.

Finally, lleeppaannttoo can use hhuubbssyyss to pass mail on to wwiiddggeett. Thus, when rrmmaaiill
receives  mail  for  system wwiiddggeett,  it  will  transmit  it  to hhuubbssyyss  for
forwarding.   Note  that hhuubbssyyss's  administrator  must  have given  lleeppaannttoo
permission to use it as a mail relay, or this would not work.

_S_e_e _A_l_s_o
AAddmmiinniisstteerriinngg CCOOHHEERREENNTT, mmaaiill
