From: Thomas Schwinge <thomas@schwinge.name>
To: Jameson Graef Rollins <jrollins@finestructure.net>, dtk <dtk@gmx.de>,
	Ali Polatel <polatel@gmail.com>
Subject: Re: [python] set rpath in setup.cfg
In-Reply-To: <87pqi1s8ln.fsf@servo.finestructure.net>
References: <6d84224ab757d84968df4db3a7b00fcb@jadE-Hamburg.de>
	<20111012153051.GE21615@hayalet>
	<d8e00c1f9be7bf018677a2c868e95e6d@jadE-Hamburg.de>
	<87pqi1s8ln.fsf@servo.finestructure.net>
User-Agent: Notmuch/0.9-101-g81dad07 (http://notmuchmail.org) Emacs/23.3.1
	(i486-pc-linux-gnu)
Date: Sun, 16 Oct 2011 22:04:23 +0200
Message-ID: <8739es3dq0.fsf@kepler.schwinge.homeip.net>
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Hi!

On Wed, 12 Oct 2011 23:34:28 -0700, Jameson Graef Rollins <jrollins@finestr=
ucture.net> wrote:
> On Thu, 13 Oct 2011 08:12:03 +0200, dtk <dtk@gmx.de> wrote:
> > in my experience, it tends to cause awkward side effects that are hard =
to
> > debug, the main problem being that it overrides all default paths and is
> > hard to target at a single problematic application.
>=20
> I think it's fairly straightforward to prepend a library path to the ld
> library path without overriding all defaults with something like this
> (for bash):
>=20
> LD_LIBRARY_PATH=3D/new/ld/path:$LD_LIBRARY_PATH

This is in fact not safe, and may cause subtle issues: if LD_LIBRARY_PATH
is empty initally, it'll evaluate to:

    LD_LIBRARY_PATH=3D/new/ld/path:

Of this one, the last element is empty, and ld.so will thus look into the
current directory for libc.so, for example.  Now you cd /tmp/ and enter
ls...  :-)

Or, as it once bit me, you're on a system with such an LD_LIBRARY_PATH
set (without me knowing about it).  You do glibc development, and wonder
why some commands begin acting strangely when you're in the glibc build
directory...

Thus:

    LD_LIBRARY_PATH=3D/new/ld/path${LD_LIBRARY_PATH:+:$LD_LIBRARY_PATH}


Gr=C3=BC=C3=9Fe,
 Thomas

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