best way to use emphasis within code?

[Jeremy C. Reed]

I want to use fixed font like a code block but also use italics and bold 
at same time.

For example in HTML:

<tt>$ <b>mail -u <i>user</i></b></tt>

What is the best way to do this in markdown, especially if I have several 
lines of content that needs to be spaced out correctly?

Thanks

Jeremy C. Reed