Re: bug when 'cd ..' to a directory who's parent has been deleted

[Greg Wooledge]

On Mon, Feb 08, 2016 at 10:09:29AM -0500, Chet Ramey wrote:
> On 2/8/16 9:59 AM, Andreas Schwab wrote:
> > Chet Ramey <chet.ramey@case.edu> writes:
> > 
> >> `cd ..' should fail, since the parent no longer exists, and the pathname
> >> canonicalization should fail, since there's presumably no longer a valid
> >> path to reach the current directory.  No value for $PWD is correct.
> > 
> > ${PWD%/*} would be a reasonable value.  FWIW, this is what ksh uses in
> > this case, it doesn't fail.
> 
> Why would that be more reasonable than anything else?  It references a
> path that doesn't exist.

Bash and ksh both behave somewhat similarly:

imadev:~$ mkdir -p /tmp/a/b
imadev:~$ cd /tmp/a/b

(in another window)
$ rm -rf /tmp/a

(in the first window)
imadev:/tmp/a/b$ cd ..
bash: cd: ..: No such file or directory
imadev:/tmp/a/b$ cd /tmp
imadev:/tmp$ ksh
$ mkdir -p /tmp/a/b
$ cd "$_"

(in another window)
$ rm -rf /tmp/a

(in the first window)
$ cd ..
ksh: ..:  not found
$ pwd
ksh: pwd: permission denied
$ echo "$PWD"
/tmp/a/b

That's ksh88, for what it's worth.

I can't really imagine a scenario where the current directory exists
but the parent does not.  So I'm merely assuming that the original
poster meant BOTH the current and parent directories are gone.