Re: `cd .` in non-existent directory leads into weird corner case

[Vincent Lefevre <vincent@vinc17.net>]

On 2012-04-02 12:15:59 +0200, Mikael Magnusson wrote:
> On 2 April 2012 11:52, Richard Hartmann <richih.mailinglist@gmail.com> wrote:
> > On Tue, Mar 27, 2012 at 16:34, Bart Schaefer <schaefer@brasslantern.com> wrote:
> >
> >> However, I've always been a little puzzled about the decision to set
> >> $PWD to "." in this case.  Bash remembers the relative location:
> >
> > Just to make sure this does not get lost, do we agree that not
> > changing $PWD to a literal dot would make sense? Escalating the ENOENT
> > to the user is probably the best approach.
> 
> Weird, when I try making a directory and remove it, I can still cd ..
> to the parent... I can even cd into the dir with another shell (via
> /proc/$$/cwd), and cd .. to the correct parent dir from that other
> shell.

This seems to depend on the file system. The following script

tst()
{
  base=`pwd`

  echo "Test 1"
  mkdir dir
  cd dir
  rmdir ../dir
  pwd
  cd .
  pwd
  cd ..
  pwd

  cd "$base"

  echo "Test 2"
  mkdir dir
  cd dir
  rmdir ../dir
  pwd
  cd ..
  pwd
}

tst

under NFS sometimes gives with zsh 4.3.12:

Test 1
/home/vlefevre/dir
tst:cd:9: no such file or directory: .
/home/vlefevre/dir
tst:cd:11: no such file or directory: ..
/home/vlefevre/dir
Test 2
/home/vlefevre/dir
tst:cd:21: no such file or directory: ..
/home/vlefevre/dir

and sometimes:

Test 1
/home/vlefevre/dir
tst:cd:9: no such file or directory: .
/home/vlefevre/dir
tst:cd:11: no such file or directory: ..
/home/vlefevre/dir
Test 2
/home/vlefevre/dir
/home/vlefevre

and sometimes:

Test 1
/home/vlefevre/dir
.
/home/vlefevre
Test 2
/home/vlefevre/dir
tst:cd:21: no such file or directory: ..
/home/vlefevre/dir

>From /tmp, I always get:

Test 1
/tmp/dir
.
/tmp
Test 2
/tmp/dir
/tmp

With sh (dash):

Test 1
/home/vlefevre/dir
cd: 26: can't cd to .
/home/vlefevre/dir
/home/vlefevre
Test 2
/home/vlefevre/dir
/home/vlefevre

and

Test 1
/tmp/dir
cd: 26: can't cd to .
/tmp/dir
/tmp
Test 2
/tmp/dir
/tmp

respectively.

With zsh in ksh emulation:

Test 1
/home/vlefevre/dir
tst:cd:9: no such file or directory: .
/home/vlefevre/dir
tst:cd:11: no such file or directory: ..
/home/vlefevre/dir
Test 2
/home/vlefevre/dir
tst:cd:21: no such file or directory: ..
/home/vlefevre/dir

or

Test 1
/home/vlefevre/dir
.
.
Test 2
/home/vlefevre/dir
/home/vlefevre

-- 
Vincent Lefèvre <vincent@vinc17.net> - Web: <http://www.vinc17.net/>
100% accessible validated (X)HTML - Blog: <http://www.vinc17.net/blog/>
Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)