<p>Should it be possible to directly send G-code to the printer serial connection using pipes under Linux?</p>

<p>Example:</p>

<pre><code>echo M106 &gt; /dev/ttyUSB0
</code></pre>

<p>My controller runs at 250000 baud, I have tried setting the TTY baud rate to 250 kBd with: </p>

<pre><code>stty -F /dev/ttyUSB0 250000
</code></pre>

<p>But, unfortunately, this particular baud rate appears to be unsupported under Ubuntu, giving the error: </p>

<pre><code>stty: invalid argument ‘250000’
</code></pre>

This forum page
strongly suggests you should be using
```
setserial
```
for a port, not
```
stty
```
, which is for terminals.  I'd give the code snippets there a try.
Alternatively,
stackoverflow
has a similar discussion, with somewhat more complicated modifications.
Are you sure you can't talk with your printer at a lower baud rate than the maximum capability of the printer-end?