From: rog@vitanuova.com
To: 9fans@cse.psu.edu
Subject: Re: [9fans] ls, rc question -- proposed change to rc/glob.c
Date: Mon, 22 Mar 2004 22:56:26 +0000 [thread overview]
Message-ID: <1cfa5e29c25777a3842f88338e39b634@vitanuova.com> (raw)
In-Reply-To: <5703c110d2b1be322b2013b834545d1d@collyer.net>
i'm in a minority here, so i'll say this and then shut up.
i think the symlink comparison is not really valid, as a symbolic link
is a potentially useful entity in its own right (hence tools that can
look at them in both ways) whereas a duplicate name signifies nothing
beyond the fact that the directory might be a union directory; there's
nothing useful that can be done with the name.
what this discussion boils down to is epitomised by boyd's:
> large N% of the time it's not a problem, so Leave It Alone:
basically union directories are used hardly at all, and when they are,
it's generally only in "special purpose" places, such as /bin, /cron,
etc. of course, they're crucial in the places where they are used,
but it's not really the general mechanism that one gets the impression
of when reading the documentation (as one quickly realises when trying
to do unusual things with it, such as bind onto directories in
/n/dump).
i have a feeling almost nothing would break if the kernel was changed
to disallow reading of union directories completely...
> the arguments seem to focus on whether with a change here or there
> they could be got to do a little more work (eg, by allowing * to
> iterate exactly once over all services, protocols, say).
> i don't think it's that essential in practice.
not essential.
it'd just be nice.
for what it's worth, i had a look through the programs that
geoff mentioned, categorising how they react to union directories.
no (or unlikely) adverse consequences:
pptpd
controls own namespace
bitsy/keyboard
faces
ps
winwatch
displays duplicates (but union unlikely)
aux/depend
exportfs
reflects duplicates in exported namespace
cron
du
aux/listen
mk
do their own duplicate elimination
history
could produce erroneous results on snap (but union unlikely)
displays duplicate entries/info:
acme
news
display duplicate entries
netstat
displays duplicate info
inefficient:
mkfs
gzip/zip
scp
produces duplicate copy of file
vac
stores duplicate directory entries
questionable:
rm
removes all entries, including hidden ones
erroneous:
ip/ftpd
ls
displays duplicates, with non-stable reordering of entries.
diff
reports spurious extra entries
tar
doesn't work properly, (but probably for reasons
unrelated to union directory reading (try {tar c /bin | tar t})
unknown:
replica/revproto
not sure.
next prev parent reply other threads:[~2004-03-22 22:56 UTC|newest]
Thread overview: 96+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-03-18 21:40 [9fans] ls question David Tolpin
2004-03-18 21:58 ` Russ Cox
2004-03-18 22:05 ` Russ Cox
2004-03-18 23:00 ` [9fans] ls, rc question David Tolpin
2004-03-18 23:31 ` [9fans] dirread David Tolpin
2004-03-18 23:49 ` ron minnich
2004-03-19 0:14 ` boyd, rounin
2004-03-19 3:38 ` rsc
2004-03-19 3:41 ` [9fans] ls, rc question rsc
2004-03-19 5:32 ` David Tolpin
2004-03-19 5:45 ` boyd, rounin
2004-03-19 5:50 ` ron minnich
2004-03-19 6:45 ` boyd, rounin
2004-03-19 9:07 ` Charles Forsyth
2004-03-19 9:24 ` Richard Miller
2004-03-19 9:33 ` boyd, rounin
2004-03-19 9:39 ` Richard Miller
2004-03-19 9:46 ` Geoff Collyer
2004-03-19 10:11 ` Richard Miller
2004-03-19 10:42 ` Charles Forsyth
2004-03-19 10:03 ` Charles Forsyth
2004-03-19 9:38 ` [9fans] Bind, look, everything is duplicated David Tolpin
2004-03-19 7:01 ` [9fans] ls, rc question Micah Stetson
2004-03-19 7:57 ` [9fans] ls, rc question -- proposed change to rc/glob.c David Tolpin
2004-03-19 8:13 ` Rob Pike
2004-03-19 8:18 ` David Tolpin
2004-03-19 8:24 ` David Tolpin
2004-03-19 8:27 ` Rob Pike
2004-03-19 8:52 ` David Tolpin
2004-03-19 9:16 ` Richard Miller
2004-03-19 9:29 ` boyd, rounin
2004-03-19 9:41 ` Geoff Collyer
2004-03-19 10:09 ` boyd, rounin
2004-03-19 10:50 ` Geoff Collyer
2004-03-19 11:12 ` David Tolpin
2004-03-19 12:31 ` Charles Forsyth
2004-03-19 12:53 ` boyd, rounin
2004-03-19 13:59 ` David Presotto
2004-03-19 14:44 ` David Tolpin
2004-03-19 17:57 ` Russ Cox
2004-03-19 18:04 ` David Tolpin
2004-03-19 20:31 ` Geoff Collyer
2004-03-22 22:56 ` rog [this message]
2004-03-22 23:19 ` Scott Schwartz
2004-03-22 23:50 ` Charles Forsyth
2004-03-23 0:28 ` rog
2004-03-23 0:40 ` Charles Forsyth
2004-03-23 0:49 ` Charles Forsyth
2004-03-23 2:12 ` ron minnich
2004-03-23 2:16 ` boyd, rounin
2004-03-23 3:15 ` rog
2004-03-23 11:13 ` a
2004-03-23 11:47 ` Geoff Collyer
2004-03-19 8:31 ` Richard Miller
2004-03-19 8:47 ` Geoff Collyer
2004-03-19 9:07 ` Rob Pike
2004-03-19 9:34 ` David Tolpin
2004-03-19 9:52 ` Scott Schwartz
2004-03-19 14:42 ` ron minnich
2004-03-19 16:18 ` 9nut
2004-03-19 15:34 ` david presotto
2004-03-19 15:43 ` ron minnich
2004-03-19 16:00 ` Charles Forsyth
2004-03-19 16:02 ` Charles Forsyth
2004-03-19 16:23 ` David Presotto
2004-03-19 16:34 ` Richard Miller
2004-03-19 16:47 ` a
2004-03-19 16:52 ` Richard Miller
2004-03-19 17:15 ` David Presotto
2004-03-21 20:47 ` rog
2004-03-21 20:50 ` boyd, rounin
2004-03-21 21:53 ` ron minnich
2004-03-21 22:05 ` Charles Forsyth
2004-03-21 23:29 ` Enache Adrian
2004-03-22 1:30 ` boyd, rounin
2004-03-22 10:09 ` Douglas A. Gwyn
2004-03-22 10:49 ` Charles Forsyth
2004-03-22 12:15 ` boyd, rounin
2004-03-22 18:23 ` Derek Fawcus
2004-03-23 0:06 ` boyd, rounin
2004-03-19 16:34 ` a
2004-03-19 15:53 ` lucio
2004-03-19 16:01 ` Charles Forsyth
2004-03-19 16:08 ` andrey mirtchovski
2004-03-19 16:12 ` ron minnich
2004-03-19 16:22 ` lucio
2004-03-19 19:42 ` boyd, rounin
2004-03-19 14:13 ` Russ Cox
2004-03-19 14:37 ` David Tolpin
2004-03-19 8:35 ` boyd, rounin
2004-03-19 14:19 ` Russ Cox
2004-03-18 21:59 ` [9fans] ls question David Presotto
2004-03-18 22:05 ` matt
2004-03-18 22:04 ` David Tolpin
2004-03-18 22:08 ` boyd, rounin
2004-03-19 15:59 [9fans] ls, rc question -- proposed change to rc/glob.c Tiit Lankots
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