Environment variables are not set when redirect echo through a pipeline at a function

Question

This command:

echo '18' | source meta-cmf-raspberrypi/setup-environment

Not set the environment variables as instead happened with a simply:

source meta-cmf-raspberrypi/setup-environment

With "18" in input.
The question at link: Environment variables are not set when my function is called in a pipeline

Not solve my problem because i have try:

echo '18' > >(source meta-cmf-raspberrypi/setup-environment)

Without success. How do I solve the problem?

How does `meta-cmf-raspberrypi/setup-environment` look like? — Arkadiusz Drabczyk, Apr 01 '20 at 13:02
https://wiki.rdkcentral.com/pages/viewpage.action?pageId=71011616 — Riccardo La Marca, Apr 01 '20 at 13:28
Hmm, where exactly is the contents of `setup-environment` shown? — Arkadiusz Drabczyk, Apr 01 '20 at 13:31
it doesn't matter where the command meta-cmf-raspberrypi/setup-environment comes from. — Riccardo La Marca, Apr 01 '20 at 13:31
It does, form the webpage, I can see that `setup-environment` triggers a user input/ prompt. This is a very different problem. Please update the question accordingly for more clarity. — FelixJN, Apr 02 '20 at 21:06
Is not necessary understand setup environment. The answer below solve my problem. — Riccardo La Marca, Apr 03 '20 at 08:10
Does this answer your question? [Environment variables are not set when my function is called in a pipeline](https://unix.stackexchange.com/questions/134735/environment-variables-are-not-set-when-my-function-is-called-in-a-pipeline) — roaima, Apr 03 '20 at 22:21

Kusalananda · Accepted Answer · 2020-04-01T14:00:02.860

2

In the pipeline, the script is being sourced in a separate environment. Likewise in the process substitution example. This means that variables set in the script are set in a child environment to the calling shell. Changes in a child environment can never propagate to the parent environment.

You could solve this in two ways, avoiding sourcing the script in a separate environment.

The first way would work in a shell that understand "here-strings":

source meta-cmf-raspberrypi/setup-environment <<<18

The second way is to use a standard here-document:

source meta-cmf-raspberrypi/setup-environment <<END_INPUT
18
END_INPUT

In both variations, the script is sourced in the current environment, with its input redirected from the here-string/here-document.

edited Apr 01 '20 at 14:00

answered Apr 01 '20 at 13:34

Kusalananda

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Thank you, works perfectly! – Riccardo La Marca Apr 01 '20 at 13:46
1

@RiccardoLaMarca instead of here-docs or here-strings (which will use a temporary file in bash, zsh and other shells), you could use a process substitution: `source script < <(echo 18)` – Apr 01 '20 at 16:47
Thanks also more mosvy – Riccardo La Marca Apr 02 '20 at 10:37

Environment variables are not set when redirect echo through a pipeline at a function

1 Answers1