How to run command with dynamic sub command

[jokiefer]

Hi folks,

i tried to install the specific gdal version, depending on the installed os gdal binaries.

commands_pre =
    pip install gdal=="`gdal-config --version`.*"

But tox will escape the command like:

py311-django41: commands_pre[0]> pip install 'gdal==`gdal-config --version`.*'
ERROR: Invalid requirement: 'gdal==`gdal-config --version`.*'

Why does tox surround the package with ' chars?

[jokiefer]

currently i developed a workaround for me:

run

echo "gdal==`gdal-config --version`.*" >> requirements-gdal.txt

in front of the tox command and add the requirements-gdal.txt to the deps:

deps=
    -rrequirements-gdal.txt

for my ci jobs this worked. But the initial question is not answered.

[gaborbernat]

Tox does not support shell command substitution (backticks or $(...)) — commands are not run through a shell by default. Tox passes arguments directly to the executable.

Your workaround of writing a requirements file is a valid approach. Alternatively:

1. Use a shell wrapper: commands_pre = bash -c 'pip install gdal==$(gdal-config --version).*' (and add bash to allowlist_externals)
2. Use the tox-backtocks plugin which adds backtick substitution support
3. Use a helper script that resolves the version and installs