In fact, I noticed that I could use the range syntax in irb. I cannot tell what caused the inconsistency for I don't have enough background on Ruby. It seems something to do with ruby libpath or something like that. I am not worried about being not able to identify the fail. It is more of my personal issue than Command-t issue. As far as i can tell the fix won't introduce new issue while it do help someone (me namely) out.