gistfile1.txt

sasha:rubinius brian$ rbx -Xdebug -e 'puts :foo'

| Breakpoint: Rubinius::Loader#debugger at kernel/loader.rb:545 (53)
| 545:           Rubinius::Debugger.start
debug> help
                help: Show information about debugger commands
       b, break, brk: Set a breakpoint at a point in a method
    tb, tbreak, tbrk: Set a temporary breakpoint
      d, del, delete: Delete a breakpoint
             n, next: Move to the next line or conditional branch
             s, step: Step into next method call or to next line
           ni, nexti: Move to the next bytecode instruction
            f, frame: Make a specific frame in the call stack the current frame
   c, cont, continue: Continue running the target thread
       bt, backtrace: Show the current call stack
             p, eval: Run code in the current context
    dis, disassemble: Show the bytecode for the current line or method
             i, info: Show information about things
                 set: Set a debugger config variable
                show: Display the value of a variable or variables
debug> dis
==== Bytecode between 45 and 56 for line 545 ====
|    45: push_const_fast :Rubinius, 13
|    48: find_const 14
|    50: send_stack :start, 0
|    53: goto 56
|    55: push_nil 
|    56: ret 
debug> ni

| Breakpoint: Rubinius::Loader#debugger at kernel/loader.rb:0 (56)
| 0: 
debug> help set
Help for Rubinius::Debugger::Command::SetVariable:
  Accessed using: set

Set a debugger config variable.

Set a debugger configuration variable. Use 'show' to see all variables.
debug> ni

| Breakpoint: Rubinius::Loader#main at kernel/loader.rb:767 (56)
| 767:           debugger
debug> 

| Breakpoint: Rubinius::Loader#main at kernel/loader.rb:768 (57)
| 768:           agent
debug> 

| Breakpoint: Rubinius::Loader#main at kernel/loader.rb:768 (58)
| 768:           agent
debug> set show_bytecode
| Set 'show_bytecode' = true
debug> ni

| Breakpoint: Rubinius::Loader#main at kernel/loader.rb:768 (60)
| 768:           agent
=> ip 60 = pop