What UNIX-like operating systems are available on x86?

• Solaris x86, SVR4-based
  (http://www.Sun.COM/)
  
• Interactive UNIX, SVR3.2-based
  (http://www.Sun.COM/software/ius/)
  
• SCO OpenServer UNIX, SVR3.2-based
  (http://www.sco.com/)
  
• SCO UNIXWare, SVR4-based
  (http://www.sco.com/)
  
• BSD/OS
  (http://www.bsdi.com/)
  

• Linux (http://www.linuxresources.com/, open source)
  
• FreeBSD (http://www.freebsd.org/, open source)
  
• NetBSD (http://www.netbsd.org/, open source)
  
• OpenBSD (http://www.openbsd.org/, open source)
  

Note that the open source versions can also be purchased on CD-ROM,
which is a convenient way to get it. For Linux, there are multiple
vendors selling CD-ROMs
(e.g., RedHat, http://www.redhat.com/).
Other systems are over the horizon, in beta, or for teaching/research.
E.g., GNU's HURD

http://www.gnu.ai.mit.edu/software/hurd/,
Tanenbaum's Minix

http://www.cs.vu.nl/~ast/minix.html,
or Lucent/Bell Labs' Plan 9,
http://plan9.bell-labs.com/

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