After further thought ...
That "auto" and "allow-auto" are synonymous indicates that, for the
"auto" group at least, the concept behind the reserved word is that of
"set of interfaces" in general and not just that of inclusion (as "auto"
might be taken to suggest) or exclusion (as "allow" suggests). For the
purposes of the -a option, the set is the set of target interfaces to
_include_. For the purposes of the --allow option, the set is the set
of target interfaces _not to exclude_. (I know that this is obvious.)
Now what about the combination of -a and --allow?
In the current program, if -a is used then --allow=auto would be
expected to have no effect. And it has no effect -- the command behaves
just like "ifup -a". OK.
If -a is used then --allow=foo would be expected to have one of two
different effects. Either:
1. to up all interfaces in the intersection of sets "auto" and "foo"
or:
2. to up all interfaces in set "foo"
In case #1, -a is interpreted in such a way that it would be natural to
give it an argument determining the set of interfaces to include. Thus
"ifup --all=foo" would include all the interfaces in the set foo;
"ifup -a" could then be interpreted as short for "ifup --all=auto"; so
"ifup --all=foo --allow=bar" would up all interfaces in foo that are
also in bar. (A further natural extension would be to allow multiple
"--all" option so that "ifup --all=foo --all=bar" would up all
interfaces in sets "foo" and "bar".)
In case #2, -a is interpreted as changing the function of "--allow" from
exclusion into inclusion. Thus "ifup --allow=foo -a" would bring up all
interfaces in set "foo".
Testing suggests that ifup version 0.6.6 implements #1. I was initially
confused because I was thinking along the lines of #2.
I still think that this passage:
Lines beginning with "allow-" are used to iden-
tify interfaces that should be brought up auto-
matically by various subsytems.
should be changed to something like:
Lines beginning with "allow-" are used to iden-
tify interfaces that should be permitted to be
brought up or down when an --allow option with
a matching argument is given on the ifup or
ifdown command line. This is intended to be
used to restrict the set of interfaces that
various subsystems are allowed to control.
It would be helpful to add:
This option can be used in combination with -a,
in which case only the interfaces listed both in
"auto" (or "allow-auto") stanzas and in stanzas
corresponding to the --allow option are acted
upon.
--
Thomas Hood <[EMAIL PROTECTED]>
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