Re: [9fans] ls, rc question -- proposed change to rc/glob.c

[Russ Cox <rsc@swtch.com>]

Rob Pike wrote:

> are you planning to change the other shells too? what about every 
> other program
> that reads directories?  what does '*' really mean? you're making 
> assumptions
> about what's right and i don't think it's clear what's right and when 
> things aren't
> clear i say leave them alone until they clear up. after something like 
> 15 years
> they still haven't cleared up.
>
> i'm not saying the behavior is right, but i'm not admitting it's 
> wrong, either.
> moreover, i can explain everything that's going on by applying a very 
> simple
> model that is clear from the documentation. that's worth a lot.


continuing this...

note how much more complicated the model gets if rc and ls
(or perhaps dirreadall) start removing duplicates from the list.
right now, it took you no time at all to find the existence of duplicates,
and then once you realize they exist, you notice them everywhere.

if the bulk of directory-processing programs remove duplicates
for themselves, then some day you run across a program that
doesn't (either out of neglect or because it doesn't fit the way the
program does directory processing).  now you know duplicates
exist again.  but nothing makes sense -- why haven't you noticed
before?  why do some programs show them and others not?
the explanation isn't simple or regular or predictable -- some do, some 
don't,
depending on their code. 

i'd rather live in the first world, where all programs agree.
the alternate universe, where illusions come and go depending on
the program, where shortcomings of the kernel are fixed by hacking
around them in user space, it's a terrible way to live.  if you want
modern unix, you know where to find it.

the clearest example i can think of in modern unix where this
happens is the handling of .. by shells in order to make symlinks
look not like symlinks, while the kernel is still broken, as rob points
out in http://plan9.bell-labs.com/sys/doc/lexnames.pdf.  there are
plenty of others.

russ


p.s. amusingly enough, now we've filled in all the context necessary
to read boyd's first post in this thread, where he posted that url
and nothing else!