Execute xbasic with one or more of the following options:  

xbasic    --- run basic program  [input.bas]

-l                  --- only load basic program, do not execute  
-e        --- execute basic command 
--eval    --- evaluate num. expression  

Example:

xbasic testme.bas
xbasic -e 'alert 1,"Hello World !",1," OK ",b'
xbasic --eval 1+3-4*3