STDERR is merged with STDOUT in wp-env run commands

[westonruter]

Description

Commands that output to STDERR are unexpectedly combined with STDOUT when run in a container via wp-env run.

Step-by-step reproduction instructions

When running the following command, no output should be displayed since ls writes the error message to STDERR:

ls non_existent_file 2>/dev/null

Nevertheless, with wp-env run, this is not the case:

npm run --silent wp-env run cli ls non_existent_file 2>/dev/null

This unexpectedly outputs:

ls: non_existent_file: No such file or directory

No output should be printed since STDERR is being redirected to /dev/null.

Screenshots, screen recording, code snippet

No response

Environment info

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Please confirm that you have searched existing issues in the repo.

• Yes

Please confirm that you have tested with all plugins deactivated except Gutenberg.

• Yes