backtrace

        # Exception.backtrace

(from ruby core)
---
    exception.backtrace    -> array or nil

---

Returns any backtrace associated with the exception. The backtrace is an
array of strings, each containing either ``filename:lineNo: in
`method''' or ``filename:lineNo.''

    def a
      raise "boom"
    end

    def b
      a()
    end

    begin
      b()
    rescue => detail
      print detail.backtrace.join("\n")
    end

*produces:*

    prog.rb:2:in `a'
    prog.rb:6:in `b'
    prog.rb:10

In the case no backtrace has been set, `nil` is returned

    ex = StandardError.new
    ex.backtrace
    #=> nil