HP-UX Reference (11i v2 04/09) - 1 User Commands N-Z (vol 2)

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pathalias(1) pathalias(1)

-g file Dump graph edges into ﬁle in the form host

>host for simple connections and

host

@<tab>host for network connections (from hosts to networks only).

-s file Dump shortest path tree into ﬁle in the form host<tab>&[

@]host[!](cost), includ-

ing both connections from hosts to networks and from networks to hosts. This data

may be useful for generating lists of one-way connections.

WARNINGS

The

-i option should be the default.

The order of arguments is signiﬁcant. In particular,

-i and -t should appear early in the command

line.

pathalias can generate hybrid (that is, ambiguous) routes, which are abhorrent and most certainly

should not be given as examples in a manpage. Experienced mappers largely shun

@ when preparing

input; this is historical, but also reﬂects UUCP’s simplistic syntax for source routes.

Mixed-mode paths are ambiguous because the precedence of

@ versus ! is not speciﬁed, varies from host

to host, and is conﬁgurable. They should rarely be used.

Multiple

@s in routes are prohibited by many mailers. To circumvent this restriction, mailers instead

support the "magic %" rule, described below. When

pathalias would otherwise generate a path con-

taining multiple

@s, it instead generates a path to which the "magic %" rule can be correctly applied.

Basically, the "magic %" rule for generating paths is "when constructing a path that would require multi-

ple

@s, replace all but the rightmost @ with %.

When a mailer that supports the "magic %" rule receives a message that was routed to it via

..path..

@host, it processes the route as follows:

1. Remove the trailing

@host part of the route.

2. Examine the remaining route from right to left, proceeding to the next step when a

! is seen.

If a

% is seen, change it to @ and proceed to the next step immediately.

3. Continue processing the message using the modiﬁed route. If the modiﬁed route contains both

! and @ characters, the exact selection of the next host to route the message is governed by

the speciﬁc precedence of ! vs. @ at this host.

For example, if a host,

jazz.nonesuch.com

, received a message with a path

foo!joe%castle.hrh.gov.uk@jazz.nonesuch.com ,

the mailer would convert the

path to

foo!joe@castle.hrh.gov.uk ,

and then forward it appropriately. If the host

were conﬁgured such that

! were of higher precedence than @, the message would be for-

warded to host foo, which would then deliver the message to joe@castle.hrh.gov.uk

. If instead jazz.nonesuch.com

were conﬁgured with @ as higher in precedence, it would

forward the message to host

castle.hrh.gov.uk

, which would then deliver it to

foo!joe. (Clearly, pathalias could only correctly generate such a path if it knew the pre-

cedence at host jazz.nonesuch.com

; since the database does not contain that information,

such paths from

pathalias should be viewed with suspicion.)

The

-D option suppresses insigniﬁcant routes to domain members. This is benign, perhaps even

beneﬁcial, but confusing, since the behavior is undocumented and somewhat unpredictable.

AUTHOR

pathalias was developed by Peter Honeyman and Steven M. Bellovin.

FILES

newsgroup comp.mail.maps Likely location of some input ﬁles.