Re: just a friendly request

On Wed, Feb 17, 2016 at 2:04 AM, Liam Proven <[email protected]> wrote:
> On 16 February 2016 at 07:06, Tutun Das <[email protected]> wrote:
>> Can anyone tell me how gobo linux manages multiple versions of libraries so
>> that every application runs with correct versions of their required
>> libraries? and if it would be helpful to use modulefiles?
>
>
> As I understand it, libraries are located inside each program's own
> folder tree
Dependencies are not duplicated. Newer versions having the same soname
will be linked over the top of old ones in the combined tree, but
versions with different filenames can all be linked at once. That
behaviour is dependent on correct soname versioning, as Kenneth said,
and also on the dependent programs knowing their own limitations in
linking to a reasonable version. These are almost always reasonable
assumptions in practice, but there are still some programs that don't
like to conform.

Because you can have as many versions in /P/X as you want, you can
keep the library versions you need around as long as necessary. You
can also keep non-library programs around in multiple versions, and
there is an (optional) feature to create versioned links to the
executables too in order to keep them all available on request, since
those don't usually get different names.

Some of the tools, like ChrootCompile, build up chroots matching
exactly the specified dependencies and will always have (supposedly)
correct versions available. That's what's used for building binary
packages, and to test that those specified dependencies are valid. The
Runner tool Lucas described uses namespaces to a similar end.
modulefiles could in theory be helpful, but in practice most things
work and the rest the Runner tool will now deal with.
-Michael