Allow overwriting Bun.stdout and Bun.stderr

[TomasHubelbauer]

What is the problem this feature would solve?

I have a piece of code where a method writes to the standard output using console.log and when a condition is met, it should instead write to a file.

I have no control over the implementation of the method, so I am looking for ways to redirect the console.log and console.error calls.

I tried doing this:

const file = Bun.file('file-name.ext');
Bun.stdout = file;
Bun.stderr = file;

method(); // Calls `console.log` inside

However the standard output and standard error streams remained the terminal-attached ones, the file was created, but remained empty.

What is the feature you are proposing to solve the problem?

Make Bun.stdout and Bun.stderr read-write and respect the overriden values when using these internally as sinks for console methods. (But this should probably also affect process.stdout and process.stderr maybe?

What alternatives have you considered?

No response

[heimskr]

Would it suffice to replace the console.log global?

console.log = (...args) => {
    writeToFile("filename", ...args);
};

[TomasHubelbauer]

That's what I'm doing right now but it doesn't feel like a correct solution. A way to tell Bun to write to a different BunFile whenever stdout or stderr is written into would be preferable.

[guest271314]

console is not part of ECMA-262. ECMA-262 doesn't specify I/O at all, so whatever happens in JavaScript runtiems or engines, or doesn't happen, is completely arbitrary.

You can't really redirect console.log, which is generally a TTY, that I am aware of, you can overwrite console.log(). if console exists at all in the runtime, which it doesn't have to to be within the language of ECMA-262.

[guest271314]

I think you can solve this by making use of the tee command.

[TomasHubelbauer]

Note that this feature request is about Bun.stdout and Bun.stderr. Console method are just one example of where these sinks are used.

[guest271314]

The approach @heimskr suggested would be the simplest.

[TomasHubelbauer]

Agreed. That's why I am using it, as I've stated. The feature request still stands.

[guest271314]

Then I think you mean overwriting console, not Bun.stdout and Bun.stderr, which really have nothing to do with your situation.

[guest271314]

What happens when you continuously read process.stdout during running the code you have?