Disable progress in stdout

[Phil]

Hi all,

When running guix from a script the stdout contains various things that
should be disabled unless running interactively - you end up with a log
of stdout containing visual noise.

The -v0 switch doesn't seem to completely quell interactive feedback,
and my aim is not for silence, just for appropriate feedback when not
running manually from the console (i.e. automated via script).

Some other command-line tools have a --progress flag or similar to
disable this - is there an equivalent in Guix?


Examples of unhelpful logging when redirecting to file:

[K100% 
[#########################################################################]
[K100% 
[#########################################################################]
[K100% 
[#########################################################################]

substitute: [Kupdating substitutes from 'https://ci.guix.gnu.org'...   0.0%
substitute: [Kupdating substitutes from 'https://ci.guix.gnu.org'...  12.5%
substitute: [Kupdating substitutes from 'https://ci.guix.gnu.org'...  25.0%
substitute: [Kupdating substitutes from 'https://ci.guix.gnu.org'...  37.5%
substitute: [Kupdating substitutes from 'https://ci.guix.gnu.org'...  50.0%
substitute: [Kupdating substitutes from 'https://ci.guix.gnu.org'...  62.5%
substitute: [Kupdating substitutes from 'https://ci.guix.gnu.org'...  75.0%
substitute: [Kupdating substitutes from 'https://ci.guix.gnu.org'...  87.5%
substitute: [Kupdating substitutes from 'https://ci.guix.gnu.org'... 100.0%


Thanks,
Phil.