distros that don't set library links (ie .so -> .so.1.2.3)

Hello knowledgable folks,

I've got a basic question about shared libraries on Linux: Shouldn't
there always be a link from .so pointing to the particular version
installed/used? For example, I recall Mandrake linux a few years ago
shipped 9.x without such links, and nothing compiled until you
manually went through and created the links, or wrote a program/script
to do it.

Now am having the same problem on Suse linux. Half the libs are so.1
etc, ie specific version only, without the link from .so -> .so.1.2.3,
for example. Is this considered a bug, or what?

Am working on a system that don't have root priveleges on, so normally
the solution would be to make the links in my $HOME and set
LD_LIBRARY_PATH to include the directory where those links exists, but
the installers I'm working with switch shells and what-not so that the
env variable is lost.

But my basic question is: Shouldn't distros create those links during
installation?

Thanks
Charles

On 2008-09-12, charlie <ccosse@gmail.com> wrote:[color=blue]
> I've got a basic question about shared libraries on Linux: Shouldn't
> there always be a link from .so pointing to the particular version
> installed/used?[/color]

Not always.
[color=blue]
> For example, I recall Mandrake linux a few years ago
> shipped 9.x without such links, and nothing compiled until you
> manually went through and created the links, or wrote a program/script
> to do it.
>
> Now am having the same problem on Suse linux. Half the libs are so.1
> etc, i.e. specific version only, without the link from .so -> .so.1.2.3,
> for example.[/color]

The libblah.so link is there merely for building programs.

The resulting program does not know about anything called "libblah.so" (*).
Instead, it knows to look for a library with the appropriate "soname",
which typically has the form "libblah.so.1". The soname link libblah.so.1
-> libblah.so.1.0.0.0.1 is _required_ at runtime.

$ strings /bin/bash | grep ncurses
libncurses.so.5
$ objdump -x /usr/lib/libncurses.so | grep SONAME
SONAME libncurses.so.5

(*--Unless the library has the degenerate soname "libblah.so".)
[color=blue]
> But my basic question is: Shouldn't distros create those links during
> installation?[/color]

During installation of the runtime-only component of the library, no.
During installation of the development component, yes.

--
Paul Kimoto
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