Re: How to overwrite a symbolic link?

[Peng Yu]

On Fri, May 7, 2010 at 10:16 AM, Eric Blake <eblake@redhat.com> wrote:
> On 05/07/2010 09:02 AM, Peng Yu wrote:
>> Suppose I need to modify one primary file slightly to do something a
>> little bit different. But I still need to do the original job,
>> therefore I need to keep it the original M files. I can copy the whole
>> directory and then modify one file in the newly copied N files. But
>> I'll lose track of which file has been changed later on, which is
>> important to me.
>
> Consider using a version control system.  Track the contents of your
> directory under your favorite VCS, like git, and then you can use
> version control commands to generate the delta for both primary and
> secondary files across any state that you committed.

I can't use version control for
1. I need to frequently change file names.
2. Both primary and secondary files could be of hundred of MB or even GB.

> Or, for a one-shot solution, you could use a BSD union mount, where the
> difference between the mount overlay and the original directory shows
> exactly what was modified.

The problem is that if I have many directories that form a complex
copying graph. It is not possible to keep track of all the possible
lineages. Also, I need to avoid change multiple copies of the same
file.

> But overloading bash's > and >> operators is not possible.

Is it because the underlying library that used in bash doesn't support
the semantic of symbolic link that I propose? Or it is because of the
OS?

Is it possible to modify source code of bash to change the semantics
of symbolic link.

-- 
Regards,
Peng