.TH PATHS 8
.tr ~
.SH NAME
paths \- smail routing database
.SH DESCRIPTION
The
.I paths
file is the routing database for
.IR smail .
Each line of the file provides routing information
to either a host or to a domain.  Each line should
have either two or three tab (ascii~0x9) separated fields.
The format of each line in the paths file is:
.tr ~
.sp
.ce
\fIkey~~route~~~[cost]\fP
.sp
The
.I key
field is the key on which searches are performed.
Typically this is either a UUCP host name or a domain name.
.I smail
uses a binary search algorithm when searching the database,
so the keys must be sorted in ascending order.
Case is ignored when searching, so the keys should be converted
to lower case before sorting (see
.IR lcase (8)
and
.IR pathproc (8)).
.B Warning:
There is a bug in
.I sort -f,
so don't use it.  Convert the keys to lower case, and then sort.
.PP
The
.I route
field is a "printf" string that details the route that mail to the
.I key
should take.
See
.I pathalias
documentation for details.
.PP
The optional
.I cost
field is used by
.I smail
to determine whether to simply queue outbound
UUCP mail, or to attempt immediate delivery
(usually by invoking
.IR uucico ).
If the cost field is present, and the value is at or below
.IR smail "'s"
.I queueing threshold
then the mail will be queued and an attempt at immediate delivery
will be made.  This will speed mail delivery between hosts who
enjoy a cheap uucp link, like a hardwired line or some other
low cost transport medium, while allowing mail sent over more
expensive media to accumulate before transmission.
If the field is absent, the cost defaults to a value
above the
.I queueing threshold.
The default value for the queueing threshold is equal to the pathalias
cost DEDICATED+LOW.  Thus, direct links with cost DEDICATED+LOW or less
will see immediate delivery, while the others are queued for later delivery.
.SH EXAMPLE
Here's a sample paths file for a small host, like a pc, that doesn't
want to maintain complete routing information.  It illustrates
most of the aspect of the
.I paths
file.  Assme that the pc's name is
.I mypc,
and that it's in domain
.I .mydomain.
Also, assume that it has a dedicated link to
a smart host named
.I bighub,
and that
.IR bighub 's
administrator has given
.I mypc
.B permission
to use
.I bighub
as a mail relay.
Lastly, assume that
.I mypc
has a dialed on demand link to another computer named
.I friend.
.nf
.sp
.in +5
\fIpathalias\fP input
.sp
 mypc =	.mypc.mydomain
 mypc friend(DEMAND), bighub(DEDICATED)
 smart-host = bighub
.sp
\fIpaths\fP file produced by \fIpathalias -f inputfile|pathproc\fP
.sp
 .mypc.mydomain	%s	0
 bighub	bighub!%s	95
 friend	friend!%s	300
 mypc	%s	0
 smart-host	bighub!%s	95
.in
.sp
.fi
.SH SEE ALSO
pathalias - by Peter Honeyman
.br
smail(8), lcasep(8), pathproc(8)
.SH VERSION
@(#)paths.8	2.5 (smail) 9/15/87