Do somebody know what are the Operating Systems that implemented capabilities (i.e. Posix 1e)?

  • are they compatible?
  • will capabilities reduce portability to Linux only?

1 Answer 1


Specifically POSIX 1e; apparently only IBM AIX and SGI IRIX.

POSIX is an IEEE and ISO/IEC standard and stands for Portable Operating System interface. As far as I understand this, any utility etc. that is fully POSIX compliant is portable between any OS:s that claim at least partial POSIX compliance.

OpenGroup maintains a list of POSIX-certified operating systems. Linuxhints has a list of POSIX-compliant OS:s. Yet another list is in the POSIX Wikipedia article.

Current standard is 1003.1-202x. POSIX 1e (IEEE 1003.1e) was withdrawn after Draft 17. According to this USENET posting by Casey Schaufler:

I was the final technical editor of the document, and had the unpleasant task of requesting its withdrawl after the completion of Draft 17.

In the end, only SGI and IBM cared enough about it to continue working on it, IBM would not pay for travel, and twice in Poughkeepsie was all I could handle.

More to the point, standards development fell off of the list of important things for computer companies right about 1995, and the security effort fell victem to that.

There where a number of issues with the Draft itself that didn't help. It should have been five seperate efforts (ACLs, Audit, Capabilities, Information Labels, MAC) rather that a single integrated document. The source for the draft disappeared for a year and was only partially recovered. Some sections where too ambitious for their intended purpose. Too much was designed by the working group.

As SGI and IRIX are defunct for a decade and a half, only AIX remains, and I doubt even AIX adheres to the abandoned standard. Apparently NFSv4 ACLs took its place.

When it comes to Linux distros, by far most of them aren't fully POSIX compliant. The question is rather which shells, extensions etc. are. The Linuxhint article has more details on the subject.

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