Re: How to reference external program used in shell-scripts?

[Ricardo Wurmus <rekado@elephly.net>]

Hi Hartmut,

> Am 09.08.19 um 10:54 schrieb Ricardo Wurmus:
>> Whenever an input is changed the package will be rebuilt, because we
>> can’t know if the presence of a package will affect the build or not.
>>
>> In the case of patching references the presence of the input *will*
>> affect the output (as a reference to the absolute file name will be
>> recorded).  In the case of propagated inputs it’s really the same,
>> expect that the package will also be installed into the target profile.
>
> My concerns are not about building, but about installing. A concrete
> example:
>
>   * Ansible is a Python program running ssh via a path to
>     /gnu/store/…-openssh-8.0p1/bin/ssh
>   * Mary installs ansible.
>   * Now openssh shows a serious bug and Mary updates openssh using "guix
>     -u openssh"

This is generally not a good idea, because this problem doesn’t only
affect dependent executables but all libraries as well.  Selective
upgrading means that not-upgraded packages will generally not benefit
from fixes.  This can range from libraries for extra features to really
fundamental functionality in glibc.

One could say now that the way around this problem in general would be …
to use a single global namespace for all libraries and all applications
— and this is how we would lose most of the advantages of Guix.

--
Ricardo