`--env-file` reads commented-out lines of file!

[zsiegel92]

Acknowledgements

• [X] I read the documentation and searched existing issues to avoid duplicates
• [X] I understand this is a bug tracker and anything other than a proven bug will be closed
• [X] I understand this is a free project and relies on community contributions
• [X] I read and understood the Contribution guide

Minimal reproduction URL

https://github.com/zsiegel92/tsx_env_var_bug_mwe

Problem & expected behavior (under 200 words)

The .env file in the MWE repo looks like this:

ENV_VAR=right # comment after
# ENV_VAR=wrong

Using npx tsx --env-file .env test.ts, the commented-out wrong variable is set during execution rather than the correct one. The conditions for this are:

• the correct one has a comment after the line where it's defined
• the wrong one appears below the right one

Bugs are expected to be fixed by those affected by it

• [ ] I'm interested in working on this issue

Compensating engineering work will speed up resolution and support the project

• [ ] I'm willing to offer $10 for financial support

[privatenumber]

This is not a tsx bug—it doesn't implement this feature. All unrecognized flags are just relayed to the underlying node command to handle.

I also can't reproduce with the latest Node:

$ tsx --env-file=.env ./test.ts
right
$ node -v
v22.9.0

But you're likely encountering https://github.com/nodejs/node/issues/52084