Stdin and stdout simultaneously
Is it possible to use hashcat to use both stdin and stdout with hashcat simultaneously in order to generate candidates with --stdout?

I can only get this to work if I am using a file as the input to hashcat.  If I want to feed hashcat with stdin, it doesn't work.

This is an example that won't work.

./ | ./hashcat64.bin -r ./rules/dive.rule --stdout --outfile-autohex-disable

My goal is to use hashcat and its available rules in order to modify whatever I feed it via stdin.

Should this work or is it not a feature?
Yes this already works.

You must be doing something wrong, because this is working perfectly fine here.

You can troubleshoot it with just an echo command, e.g:
echo test | ./hashcat64.bin --stdout -r ./rules/dive.rule --outfile-autohex-disable
Is there a maximum input length? Perhaps 31 or 32 characters?

I will experiment.
I'll have to review my script, but this worked as a solution:

./ | while read line; do echo $line | ./hashcat64.bin -r ./rules/dive.rule --stdout --outfile-autohex-disable;done

<output with rules>

Weird that it doesn't work without doing this.