Open System Services Porting Guide (G06.29+, H06.06+, J06.03+)

• System data files that store information about a system
• The data interchange formats used by the tar, cpio, and pax utilities
POSIX.1 Conformance
Open System Services supports all required application program interfaces defined within the
1990 edition of the POSIX.1 standard. OSS also supports some interfaces from later editions of
the standard. Open System Services provides additional functions and facilities described in the
Open System Services System Calls Reference Manual, the Open System Services Library Calls
Reference Manual, and in the man command reference pages for the corresponding functions.
Open System Services fully conforms with the 1990 edition of the POSIX.1 standard, as interpreted
by the FIPS 151-2 standard. This assertion is made without certification of Open System Services
by the National Institute of Standards and Technology (NIST).
POSIX.2 Standard
POSIX.2 standardizes many of the UNIX commands and utilities, as well as extensions that enable
user portability. POSIX.2 defines a standard interface to shell or command interpretation and
common utilities for application programs.
POSIX.2 Conformance
Open System Services supports many required shell and utility interfaces defined within the 1990
edition of the POSIX.2 standard. OSS also supports some interfaces from later editions of the
standard. OSS provides additional functions and facilities described in the Open System Services
Shell and Utilities Reference Manual, and in the online reference pages for the corresponding
utilities.
Open System Services is nearly completely compliant with the POSIX.2 standard.
XPG4 Specifications and OSS Compliance
The XPG4 specifications, sometimes referred to as the X/Open CAE Specifications, are commonly
used in the industry but were not defined by an accredited standards committee. They were defined
by X/Open, an international vendor consortium based in Reading, England, that defined
specifications for open systems. The successor to X/Open is the Open Group; information about
the Open Group and the XPG4 specifications can be found at http://www.opengroup.org.
Open System Services is complaint with both XPG4 and XPG4 Version 2. Some of the OSS
internationalized system calls, libraries, commands, and utilities are only compliant with the older
XPG3 specifications. Not all vendors deliver UNIX products that are compliant with XPG4
specifications. X/Open does not specify the implementing language; it is specified by the ISO/ANSI
C standard. One can use ISO/ANSI C or Common C compilers and still be XPG4 compliant.
OSS reference manuals describe extensions that are specific to HP for some function calls and
commands. Most calls and commands provide POSIX or ISO/ANSI C behavior. If you want to
take advantage of the Guardian environment, you need to use some of the HP extensions. To port
applications to the OSS environment, refer to the XPG4 documents.
Extensions Based on Standards or Proposed Standards
The OSS API also includes functions that are HP extensions to the XPG4 specifications, but that
are also based on proposed standards:
• Functions designed to interact with OSS files larger than approximately 2 gigabytes in addition
to smaller OSS files. These functions, often called 64-bit APIs or 64-bit functions, typically have
the number 64 in the name (for example the open64() function). These 64-bit APIs are based
on the Adding Support for Arbitrary File Sizes to the Single Unix Specification, X/Open Large
Overview of Porting 25