Possibly. If Next ported Nextstep to IRIX (and several SGI employees
  have made it clear that it is up to Next, not SGI, to do so) the
  question might be worth discussing. That nonwithstanding, Next
  zealots have flogged Nextstep around the SGI newsgroups many times.
  They haven't convinced the command-line diehards that the Next way is
  better or vice versa. Please don't try it yourself.

  However, if you are primarily interested in the "look and feel" of 
  the Nextstep user interface, you may be interested in the AfterStep
  window manager, available from 
  http://mango.sfasu.edu/~frank/afterstep/.