XSI is an optional set of interfaces to the POSIX standard. However, to
be UNIX-03 branded an implementation MUST support the XSI option.
On Thu, 2003-03-13 at 15:18, Graham Greene wrote:
> Thanks for clearing that up, I'm less confused now....
>
> Can you also explain how XSI fits into the big picture?
> The definition page has:
> "
> XSI
> The X/Open System Interface is the core application programming
> interface for C and sh programming for systems conforming to the Single
> UNIX Specification. This is a superset of the mandatory requirements for
> conformance to IEEE Std 1003.1-2001.
> "
> Does that mean that XSI is not required to be POSIX conformant?
> Is is accurate to say "XSI is a POSIX extension and not part of the core
> POSIX standard"? Or what?
>
> Graham Greene
>
> > -----Original Message-----
> > From: Nick Stoughton [mailto:yyyy@xxxxxxxxxx]
> > Sent: Thursday, March 13, 2003 5:47 PM
> > To: Graham Greene
> > Cc: yyyyyyyyyyyyyyyyy@xxxxxxxxxxxxx
> > Subject: Re: Confused...
> >
> >
> > The Single UNIX Specification version 3 is the same as POSIX.1:2001.
> >
> > This standard has been jointly developed by the IEEE and The
> > Open Group. It is both an IEEE Standard and an Open Group
> > Technical Standard.
> >
> > Abstract: This standard defines a standard operating system
> > interface and environment, including a command interpreter
> > (or "shell"), and common utility programs to support
> > applications portability at the source code level. This
> > standard is the single common revision to IEEE Std
> > 1003.1-1996, IEEE Std 1003.2-1992, and the Base
> > Specifications of The Open Group Single UNIX Specification,
> > Version 2. This standard is intended to be used by both
> > applications developers and system implementors. It comprises
> > four major components (each in an associated
> > volume):
> >
> > 1. General terms, concepts, and interfaces common to all
> > volumes of this standard , including utility conventions and
> > C-language header definitions, are included in the Base
> > Definitions volume (XBD).
> > 2. Definitions for system service functions and
> > subroutines, language-specific system services for the C
> > programming language, function issues, including portability,
> > error handling, and error recovery, are included in the
> > System Interfaces volume (XSH).
> > 3. Definitions for a standard source code-level interface
> > to command interpretation services (a "shell" and common
> > utility programs for application programs are included in the
> > Shell and Utilities volume (XCU).
> > 4. Extended rationale that did not fit well into the rest
> > of the document structure, containing historical information
> > concerning the contents of this standard and why features
> > were included or discarded by the standard developers, is
> > included in the Rationale (Informative) volume (XRAT).
> >
> >
> > On Thu, 2003-03-13 at 12:36, Graham Greene wrote:
> > > Can "The Single UNIX Specification, Version 3" be used as a
> > reference
> > > for functions that are defined by POSIX? The reason I ask
> > is because
> > > this site: http://standards.ieee.org/catalog/olis/posix.html
> > > shows 4 volumes for 1003.1-2001, where volume 1 is "System Interface
> > > (POSIX)" and for volume 2 is says "This standard is
> > equivalent to the
> > > Single UNIX Specification". Whats the difference? (I don't
> > have a grand
> > > to download them and find out.)
> > >
> > > Also, if I wanted to write a POSIX compliant application,
> > would it be
> > > more likely to run a more systems today if stuck to POSIX.1 or
> > > POSIX.2? (Again, the only thing I have access to "The Single UNIX
> > > Specification, Version 3" on www.unix.org.
> > >
> > > Graham Greene
> >
> >
> >
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