Relative symbolic links damaged by Finder

Question

I have little experience of these matters and would be grateful if somebody could explain the apparent differences between command line and Finder use of relative symbolic links. The example below examines relative symbolic link z before, during and after it has been moved twice by the Finder.
G4:~ neville$ cd /x/y
G4:y neville$ ln -s ../ z
G4:y neville$ ls -l
total 8
lrwxr-xr-x 1 neville staff 3 4 Jul 21:46 z -> ../
Move z to x with Finder.
G4:y neville$ cd ../
G4:x neville$ ls -l
total 8
drwxr-xr-x 3 neville staff 102 4 Jul 21:48 y
lrwxr-xr-x 1 neville staff 3 4 Jul 21:46 z -> ../
The above listing is as I would expect and Finder's Get Info confirms that z points to root.
Move z to y with Finder.
G4:x neville$ cd y
G4:y neville$ ls -l
total 8
lrwxr-xr-x 1 neville staff 3 4 Jul 21:46 z -> ../
The above listing is as I would expect but Finder's Get Info still shows z pointing to root.
Is it possible that the first Finder move converts the Finder's view of z to an absolute path so that subsequent Finder moves no longer maintain the correct relative relationship? Clearly the Terminal continues to report what one would expect although, unfortunately, double clicking z appears to confirm the Finder's incorrect interpretation.
How can I ensure that the Finder does not alter relative symbolic links and hence maintain consistency between Terminal and Finder?

Answer 1

Neville Hillyer wrote:
I was not aware that the Finder had a cache - where is it?
In the Finder process.
killall Finder is a little drastic - is there a way to clear the cache or force an update without relaunching the Finder?
No. The cache is there to prevent repeated disk accesses. It wouldn't help to store such a cache on disk.
I wonder if this cache foible is likely to ever result in serious loss of data due to imperfect backups etc - can anybody think of any such issues?
No. This is only in the Finder processes. If your backups relied on the Finder, opened relative symbolic links, then moved them around, then opened them again, it might have problems. That would be a really wacky backup program.
Symbolic links are UNIX things and, as such, are rarely manipulated by the Finder. The expectation is that anyone using symbolic links will do so from a shell.
My understanding is that relative links are often used by applications during normal operation and installation.
Not often. When they are used, they are rarely opened with the Finder and then moved.
I came across this while customising Thunderbird for easy deployment with different users/Macs. Relative links made the task much easier.
The links themselves have not been changed. They will work fine in Thunderbird.
There is an almost total lack of information in man pages about relative links
There is plenty of information. It is mostly in developer documentation related to file systems.
It would be much more helpful if Finder Get Info were to display relative paths in the same way as the Terminal ie: z -> ../
That would only make the problem worse. Get Info clearly shows the Original being in the wrong location. The Finder was designed for Aliases, not symbolic links. Symbolic links work in the Finder a whole lot better than Aliases work in the Terminal.