Run node yup.js -? for info on flags. Or, read this:
yup.js by Conor O'Brien
flag name | purpose
===========+===============================================
-l | "local"; runs following arg as yup code
-d | "debug"; display stack at each step
-s | "string input"; designates the next item as a
| string, interpreted as series of ASCII char
| codes
-n | "numeric input"; designates the next item as
| a number
-w | "whitespacevariant"; notices extra spaces
| in code
-r | "no round"; does not round long decimals
-c | "disable comments"
-p | "print stack"; prints the contents of the
| stack in the end
-x | set decimal place to which to round
-cheat | ...
-t | translate a cheat program to a regular one
-te | -t, but eliminates excess characters
Yup. That's just about it. Read the wiki for information as how to use the language.