Re: cd"": Shouldn't it fail?

[Kerin Millar]

On Sun, 28 Jan 2024 18:09:24 +0300
Oğuz <oguzismailuysal@gmail.com> wrote:

> On Sun, Jan 28, 2024 at 5:10 PM <jwo@jwo.cz> wrote:
> > POSIX Programmer's Manual (cd(1p) manpage) says this:
> >
> >       [9 unrelated special cases]
> >
> >       10. The cd utility shall then perform actions equivalent to the
> >            chdir() function called with curpath as the path argument. If
> >            these actions fail for any reason, the cd utility shall
> >            display an appropriate error message and the remainder of
> >            this step shall not be executed. [...]
> 
> Right before that, it says in 8.c:
> > If, as a result of this canonicalization, the curpath variable is null, no 
> > further steps shall be taken.
> 
> which is what happens in bash, busybox sh, dash, mksh, pdksh, oksh,
> yash, zsh, and NetBSD sh.
> 

I'm not sure that this is accurate. In my testing, bash does not even perform 
this canonicalization step, which is optional to begin with. That is, it states 
that "an implementation may" canonicalize in the manner described, and 
prescribes a course of action to take if - and only if - such canonicalization 
is performed.

I think that step #5 is the relevant one: given a null CDPATH value, the 
concatenation of <dot>, <slash> and the empty operand (usually) names an 
existing directory. This matter is also mentioned by 
https://austingroupbugs.net/view.php?id=1047.

To summarise, the behaviour of bash appears to conform with the wording of 
Issue 7 but it may have to change for Issue 8 or a later revision.

-- 
Kerin Millar