Get only last line of uname -sm output on remote server

[foxtran]

Closes #25382

Release notes:

• SSH remoting: fixed connecting when your .bashrc writes to stdout.

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[foxtran]

@cla-bot check

[cla-bot]

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[ConradIrwin]

@foxtran thanks!

Also, there are likely to be other places confused by this extra echo, as due to the way ssh works we end up doing a lot of IO over stdin/stdout; with this fixed does your setup work?

[foxtran]

with this fixed does your setup work?

Not exactly, but these errors come not from extra "echo" in .bashrc.

we end up doing a lot of IO over stdin/stdout

The other places of run_command does not try to parse the output so this part works fine.

[ConradIrwin]

Right, but when we start the SshSession we read the output and assume it is photo-bufs:

zed/crates/remote/src/ssh_session.rs

Lines 1689 to 1712 in 67a4955

	let stdout_task = cx.background_spawn({
	let mut connection_activity_tx = connection_activity_tx.clone();
	async move {
	loop {
	stdout_buffer.resize(MESSAGE_LEN_SIZE, 0);
	let len = child_stdout.read(&mut stdout_buffer).await?;
	if len == 0 {
	return anyhow::Ok(());
	}
	if len < MESSAGE_LEN_SIZE {
	child_stdout.read_exact(&mut stdout_buffer[len..]).await?;
	}
	let message_len = message_len_from_buffer(&stdout_buffer);
	let envelope =
	read_message_with_len(&mut child_stdout, &mut stdout_buffer, message_len)
	.await?;
	connection_activity_tx.try_send(()).ok();
	incoming_tx.unbounded_send(envelope).ok();
	}
	}
	});

I suspect this code is also broken in the same way, and less clear how to fix.

I wonder if a better fix could be to notice: uname output is incorrect, and prompt people to fix their .bashrc?