Use output from a command in another command

Question

I have a tox environment in which I want to run a bash command (basename) on {posargs} and use the result in a subsequent command. I've tried the various ways it is possible to do this in bash, but they haven't been working. This snippet captures the spirit of what I'm trying to accomplish.

[testenv:docs]
commands =
    export PACKAGE=$(basename {posargs})
    ls $PACKAGE

Doesn't work with env vars: tox runs every command in a new shell so when the first command finishes the env var disappears. You have to save it somewhere in a permanent storage like a file. Or change approach completely like passing preprocessed {posargs} and use them in all commands down the pipeline. — phd
– phd, Commented Jul 20, 2020 at 14:26
Another thing I tried was ls $(basename {posagrs}) but that doesn't work either because tox doesn't really use a shell. — Dan Hook
– Dan Hook, Commented Jul 23, 2020 at 13:37

Shine · Accepted Answer · 2020-07-21 21:16:14Z

2

This won't work as is. Simply because of what phd said above. The only one way is output through a file. However..

What you could do is:

tox.ini

[testenv:docs]
passenv =
    PACKAGE
whitelist_externals =
    ls
commands =
    ls {env:PACKAGE}

Inside whatever script runs tox..

export PACKAGE=$(basename {posargs})
tox

This makes use of tox's variable substitution.
The passenv configuration option alows the PACKAGE environment variable to be passed (exist) into tox.
The whitelist_externals sections enables commands (ls) not installed by tox (outside it's environment basically).

answered Jul 21, 2020 at 21:16

Shine

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