Re: [9fans] mishandling empty lists - let's fix it

[John Stalker <stalker@maths.tcd.ie>]

> Does anyone agree with me that it needs fixing?

For what it's worth, I agree that it's a problem.  Maybe it's
just the fact that I'm a mathematician, but I've always felt
that any command which accepts a list of files should behave
the way I would expect when presented with an empty list.
Cat, rm, chmod, etc. do not.  At a minimum I think we should
try to avoid creating further exceptions.

Does it need fixing?  Implementing it properly would break most
shell scripts I've written.  If there were renamed versions of
cat, rm, chmod, etc. which treated empty lists in the expected
way then I would probably use them in situations were portability
is not an issue.  It would remove a frequent source of bugs and
leave me with one less thing to worry about.

Then there is the shell.  If you only use commands which behave
sanely for empty lists then the current globbing rules are a
pain.  Changing them to, for example, expand * to `' in an
empty directory breaks too many things.  I've learned to avoid
globbing as much as possible.  In any shell with command
substitution globbing is unnecessary, and is often dangerous.
I would happily use a shell with NO globbing, just to avoid
another source of worries.

--
John Stalker
School of Mathematics
Trinity College Dublin
tel +353 1 896 1983
fax +353 1 896 2282