Consider adding support for writing to stdout when reading from stdin

[bil0u]

I am trying to integrate markdownlint-cli2 as an external formatter in Zed editor. To do so, the formatter should be able to read some content from stdin and outputting the formatted content to stdout. (See official Zed docs)

I found that markdownlint-cli2 is able to read from stdin using the glob argument -, but does not print the formatted content to stdout when used in conjunction with --fix. Maybe this is a normal/desired behavior ?

Thanks for your time !

What did you do?

$ echo "# Title\n\n\n\nContent" | markdownlint-cli2 - --fix
markdownlint-cli2 v0.18.1 (markdownlint v0.38.0)
Finding:
Linting: 1 file(s)
Summary: 2 error(s)
stdin:3 MD012/no-multiple-blanks Multiple consecutive blank lines [Expected: 1; Actual: 2]
stdin:4 MD012/no-multiple-blanks Multiple consecutive blank lines [Expected: 1; Actual: 3]

What did you expect to happen?

I expected to get the formatted content as a direct output:

$ echo "# Title\n\n\n\nContent" | markdownlint-cli2 - --fix
# Title

Content

Context

• Tool version: markdownlint-cli2 v0.18.1 (markdownlint v0.38.0)
• Operating system: macOS Sequoia 15.5

[DavidAnson]

This project does not (currently) write stdin content to stdout whether or not fix is applied.

You may instead be interested in this PR to a similar project which should enable your scenario: igorshubovych/markdownlint-cli#497

[bil0u]

Thanks for the quick response and the pointer to the related PR, very helpful!

Out of curiosity, is support for writing fixed stdin content to stdout something that’s planned for this tool, or would you consider it outside the intended scope?

[DavidAnson]

@bil0u, I am open to the idea, though I like the way this works in VS Code better. Though to be fair that is only easy once you've already written an extension. :)

At any rate, I'm not sure how I'd want this to work exactly, but I will flag it for consideration in my next update pass.