renaming the current working directory (cwd)

[Bill Hacker]

Vincent wrote:
Hi.

If my cwd gets renamed by another process, it disappears out from under
me.
To reproduce:

$ mkdir zzz1
$ cd zzz1
In another shell:

$ mv zzz1 zzz2

Back in the first shell:

$ ls
ls: .: No such file or directory
$ cd ..
cd: no such file or directory: ..
This seems to be unique to Dragonfly.  I tested on FreeBSD, NetBSD, and
Linux and, it does not affect the shell that was in the directory
because it was never deleted.  I verified, in Dragonfly, that the inode
number of the directory did not change after being renamed.
Is this a bug or a feature?

I am running DragonflyBSD 1.10.1-RELEASE


A misunderstanding, perhaps...

On FreeBSD, OS X or OpenBSD the more common action is an rm -Rf - which 
results in the original shell looking at a no-longer-valid dirtree, and 
saying so when you try to do an ls ... or whatever. 'no such file or 
directory'.

My test was to add to your test - above - 'touch fudge' while in the 
dirtree, then rm -Rf the dirtree from a different shell and try to ls or 
'touch fudge2' from the shell still in the now-removed dirtree.

As expected 'no such file or directory' was returned.

Likewise trying to backstep with 'cd ..' as the point of reference is 
lost. Needs a specific cd /path/to/whatever/still-exists

Then I tried an 'mv' with the 'fudge' file in place...

OS X 10.3.9, OpenBSd 4.2, FreeBSD 6.2 are the same as DFLY.

The original shell still shows in prompt that it is in the OLD dirtree 
and still sees the file 'fudge'.

Any other shell does not. It sees them in the new dirtree. NB: This OS X 
is using UFS, not hfs

What I believe you are seeing is neither bug nor 'feature' - just a 
normal characteristic of hardlinks, which mv will use when possible.

Your shell that sits 'IN' the mv'ed dirtree has it 'open'. Once you move 
off of it, howver, that link is eaten and you cannot go back.

HTH,

Bill