why does find_my_exec resolve symlinks?

From: Peter Eisentraut <peter_e(at)gmx(dot)net>
To: pgsql-hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: why does find_my_exec resolve symlinks?
Date: 2015-02-13 18:42:07
Message-ID: 54DE457F.2090206@gmx.net
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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(at)sss(dot)pgh(dot)pa(dot)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.

Is there a way we can consolidate these situations?

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