> I've never needed to use the rackup "rack" command directly, fortunately, if you do you ought to use a different alias

Or escape alias \rack

or $(which rack)

Hm, I've recently begun using zsh primarily and this trick doesn't work there: zsh lets you know what the alias is... bash will happily find `rack` in your `$PATH` and then run it.

(Presumably because in zsh, `which which` says it's a shell built-in, whereas in bash it finds `/usr/bin/which`, so bash doesn't seem to be caring about your aliases.)

If you have the EQUALS option set (by default it is), you can use =rack instead: http://zsh.sourceforge.net/Doc/Release/Expansion.html#g_t_00...

Lovely, thanks!