In OS X you’ve always had this weird shroud of the “Classic” environment. This type of environment was used to facilitate running things in the previous incarnation of Apple’s operating systems. Many of these have disappeared over the years. In Mavericks we see yet another go away in a very small an almost noticeable binary, bless. While this command conjures fears of getting excommunicated by a Borgia for many, for those of us in the Apple community, the bless command is used to define a folder to mount to boot to.
In 10.8 and below, there was an option to bless –folder9, used to define a OS 9/Classic system folder. Given that you can’t run those operating systems on hardware that runs 10.9 Mavericks, Apple has finally managed to rid even its most religious sounding binary of all traces of OS 9.
No, I’m not done yet. There’s one more thing. –bootBlockFile, –save9–saveX and –use9 are also gone now as they’re legacy (pretty much for OS 9) and no longer required.