Обсуждение: why does find_my_exec resolve symlinks?

Here is a scenario:

./configure --prefix=/usr/local/pgsql/9.4.1
make
make install
ln -s 9.4.1 /usr/local/pgsql/9.4
PATH=/usr/local/pgsql/9.4/bin:$PATH

And then when 9.4.2 comes out, the symlink is updated.

I think this sort of setup in variations is not uncommon.

When building other software against that installation, it would use
pg_config --includedir, pg_config --libdir, etc., but that points to
/usr/local/pgsql/9.4.1/lib instead of /usr/local/pgsql/9.4/lib, because
find_my_exec() goes out of its way to resolve symlinks in the returned
path.  If the other software saves an rpath or the bindir or something
during the build, then if I later clear out the old 9.4.1 installation,
the other software will break.

The reason for this behavior is

commit 336969e490d71c316a42fabeccda87f798e562dd
Author: Tom Lane <tgl@sss.pgh.pa.us>
Date:   Sat Nov 6 23:06:29 2004 +0000
   Add code to find_my_exec() to resolve a symbolic link down to the   actual executable location.  This allows people
tocontinue to use   setups where, eg, postmaster is symlinked from a convenient place.   Per gripe from Josh Berkus.
 

I don't quite understand what setup Josh was using there.

Is there a way we can consolidate these situations?

Peter Eisentraut <peter_e@gmx.net> writes:
> Here is a scenario:
> ./configure --prefix=/usr/local/pgsql/9.4.1
> make
> make install
> ln -s 9.4.1 /usr/local/pgsql/9.4
> PATH=/usr/local/pgsql/9.4/bin:$PATH

> And then when 9.4.2 comes out, the symlink is updated.

> I think this sort of setup in variations is not uncommon.

If it were all that common, we'd have heard people complaining before.

> The reason for this behavior is

> commit 336969e490d71c316a42fabeccda87f798e562dd
> Author: Tom Lane <tgl@sss.pgh.pa.us>
> Date:   Sat Nov 6 23:06:29 2004 +0000

>     Add code to find_my_exec() to resolve a symbolic link down to the
>     actual executable location.  This allows people to continue to use
>     setups where, eg, postmaster is symlinked from a convenient place.
>     Per gripe from Josh Berkus.

> I don't quite understand what setup Josh was using there.

IIRC, the idea was that /usr/bin/postgres might be a symlink to
/usr/local/pgsql/9.4.1/bin/postgres.  If we stop resolving symlinks,
that type of arrangement will break :-(.  Given that it's been like
this for ten years without previous complaints, I'm disinclined to
mess with it ...
        regards, tom lane