mirror of https://github.com/mkerrisk/man-pages
1397 lines
39 KiB
Plaintext
1397 lines
39 KiB
Plaintext
.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved
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.TH "<unistd.h>" P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual"
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.\" <unistd.h>
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.SH NAME
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unistd.h \- standard symbolic constants and types
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.SH SYNOPSIS
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.LP
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\fB#include <unistd.h>\fP
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.SH DESCRIPTION
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.LP
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The \fI<unistd.h>\fP header defines miscellaneous symbolic constants
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and types, and declares miscellaneous functions. The
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actual values of the constants are unspecified except as shown. The
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contents of this header are shown below.
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.SS Version Test Macros
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.LP
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The following symbolic constants shall be defined:
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.TP 7
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_POSIX_VERSION
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Integer value indicating version of IEEE\ Std\ 1003.1 (C-language
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binding) to which the implementation conforms. For
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implementations conforming to IEEE\ Std\ 1003.1-2001, the value shall
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be 200112L.
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.TP 7
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_POSIX2_VERSION
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Integer value indicating version of the Shell and Utilities volume
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of IEEE\ Std\ 1003.1 to which the implementation
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conforms. For implementations conforming to IEEE\ Std\ 1003.1-2001,
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the value shall be 200112L.
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.sp
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.LP
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The following symbolic constant shall be defined only if the implementation
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supports the XSI option; see \fIXSI Conformance\fP .
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.TP 7
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_XOPEN_VERSION
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.sp
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Integer value indicating version of the X/Open Portability Guide to
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which the implementation conforms. The value shall be 600.
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.sp
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.SS Constants for Options and Option Groups
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.LP
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The following symbolic constants, if defined in \fI<unistd.h>\fP,
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shall have a value of -1, 0, or greater, unless
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otherwise specified below. If these are undefined, the \fIfpathconf\fP(),
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\fIpathconf\fP(), or \fIsysconf\fP() functions can be
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used to determine whether the option is provided for a particular
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invocation of the application.
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.LP
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If a symbolic constant is defined with the value -1, the option is
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not supported. Headers, data types, and function interfaces
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required only for the option need not be supplied. An application
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that attempts to use anything associated only with the option is
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considered to be requiring an extension.
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.LP
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If a symbolic constant is defined with a value greater than zero,
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the option shall always be supported when the application is
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executed. All headers, data types, and functions shall be present
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and shall operate as specified.
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.LP
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If a symbolic constant is defined with the value zero, all headers,
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data types, and functions shall be present. The application
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can check at runtime to see whether the option is supported by calling
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\fIfpathconf\fP(), \fIpathconf\fP(), or \fIsysconf\fP() with the indicated
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\fIname\fP parameter.
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.LP
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Unless explicitly specified otherwise, the behavior of functions associated
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with an unsupported option is unspecified, and an
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application that uses such functions without first checking \fIfpathconf\fP(),
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\fIpathconf\fP(), or \fIsysconf\fP() is considered to be
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requiring an extension.
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.LP
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For conformance requirements, refer to \fIConformance\fP .
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.TP 7
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_POSIX_ADVISORY_INFO
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.sp
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The implementation supports the Advisory Information option. If this
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symbol has a value other than -1 or 0, it shall have the value
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200112L.
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.TP 7
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_POSIX_ASYNCHRONOUS_IO
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.sp
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The implementation supports the Asynchronous Input and Output option.
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If this symbol has a value other than -1 or 0, it shall have
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the value 200112L.
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.TP 7
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_POSIX_BARRIERS
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.sp
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The implementation supports the Barriers option. If this symbol has
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a value other than -1 or 0, it shall have the value 200112L.
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.TP 7
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_POSIX_CHOWN_RESTRICTED
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The use of \fIchown\fP() and \fIfchown\fP() is
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restricted to a process with appropriate privileges, and to changing
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the group ID of a file only to the effective group ID of the
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process or to one of its supplementary group IDs. This symbol shall
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always be set to a value other than -1.
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.TP 7
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_POSIX_CLOCK_SELECTION
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.sp
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The implementation supports the Clock Selection option. If this symbol
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has a value other than -1 or 0, it shall have the value
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200112L.
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.TP 7
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_POSIX_CPUTIME
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.sp
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The implementation supports the Process CPU-Time Clocks option. If
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this symbol has a value other than -1 or 0, it shall have the
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value 200112L.
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.TP 7
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_POSIX_FSYNC
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.sp
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The implementation supports the File Synchronization option. If this
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symbol has a value other than -1 or 0, it shall have the value
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200112L.
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.TP 7
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_POSIX_IPV6
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The implementation supports the IPv6 option. If this symbol has a
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value other than -1 or 0, it shall have the value 200112L.
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.TP 7
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_POSIX_JOB_CONTROL
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The implementation supports job control. This symbol shall always
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be set to a value greater than zero.
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.TP 7
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_POSIX_MAPPED_FILES
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.sp
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The implementation supports the Memory Mapped Files option. If this
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symbol has a value other than -1 or 0, it shall have the value
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200112L.
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.TP 7
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_POSIX_MEMLOCK
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.sp
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The implementation supports the Process Memory Locking option. If
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this symbol has a value other than -1 or 0, it shall have the
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value 200112L.
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.TP 7
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_POSIX_MEMLOCK_RANGE
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.sp
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The implementation supports the Range Memory Locking option. If this
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symbol has a value other than -1 or 0, it shall have the value
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200112L.
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.TP 7
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_POSIX_MEMORY_PROTECTION
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.sp
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The implementation supports the Memory Protection option. If this
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symbol has a value other than -1 or 0, it shall have the value
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200112L.
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.TP 7
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_POSIX_MESSAGE_PASSING
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.sp
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The implementation supports the Message Passing option. If this symbol
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has a value other than -1 or 0, it shall have the value
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200112L.
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.TP 7
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_POSIX_MONOTONIC_CLOCK
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.sp
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The implementation supports the Monotonic Clock option. If this symbol
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has a value other than -1 or 0, it shall have the value
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200112L.
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.TP 7
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_POSIX_NO_TRUNC
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Pathname components longer than {NAME_MAX} generate an error. This
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symbol shall always be set to a value other than -1.
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.TP 7
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_POSIX_PRIORITIZED_IO
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.sp
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The implementation supports the Prioritized Input and Output option.
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If this symbol has a value other than -1 or 0, it shall have
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the value 200112L.
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.TP 7
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_POSIX_PRIORITY_SCHEDULING
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.sp
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The implementation supports the Process Scheduling option. If this
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symbol has a value other than -1 or 0, it shall have the value
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200112L.
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.TP 7
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_POSIX_RAW_SOCKETS
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.sp
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The implementation supports the Raw Sockets option. If this symbol
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has a value other than -1 or 0, it shall have the value 200112L.
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.TP 7
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_POSIX_READER_WRITER_LOCKS
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.sp
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The implementation supports the Read-Write Locks option. This is always
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set to a value greater than zero if the Threads option is
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supported. If this symbol has a value other than -1 or 0, it shall
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have the value 200112L.
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.TP 7
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_POSIX_REALTIME_SIGNALS
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.sp
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The implementation supports the Realtime Signals Extension option.
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If this symbol has a value other than -1 or 0, it shall have the
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value 200112L.
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.TP 7
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_POSIX_REGEXP
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The implementation supports the Regular Expression Handling option.
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This symbol shall always be set to a value greater than
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zero.
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.TP 7
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_POSIX_SAVED_IDS
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Each process has a saved set-user-ID and a saved set-group-ID. This
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symbol shall always be set to a value greater than zero.
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.TP 7
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_POSIX_SEMAPHORES
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.sp
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The implementation supports the Semaphores option. If this symbol
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has a value other than -1 or 0, it shall have the value 200112L.
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.TP 7
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_POSIX_SHARED_MEMORY_OBJECTS
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.sp
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The implementation supports the Shared Memory Objects option. If this
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symbol has a value other than -1 or 0, it shall have the
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value 200112L.
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.TP 7
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_POSIX_SHELL
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The implementation supports the POSIX shell. This symbol shall always
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be set to a value greater than zero.
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.TP 7
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_POSIX_SPAWN
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.sp
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The implementation supports the Spawn option. If this symbol has a
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value other than -1 or 0, it shall have the value 200112L.
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.TP 7
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_POSIX_SPIN_LOCKS
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.sp
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The implementation supports the Spin Locks option. If this symbol
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has a value other than -1 or 0, it shall have the value 200112L.
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.TP 7
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_POSIX_SPORADIC_SERVER
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.sp
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The implementation supports the Process Sporadic Server option. If
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this symbol has a value other than -1 or 0, it shall have the
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value 200112L.
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.TP 7
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_POSIX_SYNCHRONIZED_IO
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.sp
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The implementation supports the Synchronized Input and Output option.
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If this symbol has a value other than -1 or 0, it shall have
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the value 200112L.
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.TP 7
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_POSIX_THREAD_ATTR_STACKADDR
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.sp
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The implementation supports the Thread Stack Address Attribute option.
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If this symbol has a value other than -1 or 0, it shall have
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the value 200112L.
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.TP 7
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_POSIX_THREAD_ATTR_STACKSIZE
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.sp
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The implementation supports the Thread Stack Size Attribute option.
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If this symbol has a value other than -1 or 0, it shall have
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the value 200112L.
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.TP 7
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_POSIX_THREAD_CPUTIME
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.sp
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The implementation supports the Thread CPU-Time Clocks option. If
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this symbol has a value other than -1 or 0, it shall have the
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value 200112L.
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.TP 7
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_POSIX_THREAD_PRIO_INHERIT
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.sp
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The implementation supports the Thread Priority Inheritance option.
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If this symbol has a value other than -1 or 0, it shall have
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the value 200112L.
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.TP 7
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_POSIX_THREAD_PRIO_PROTECT
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.sp
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The implementation supports the Thread Priority Protection option.
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If this symbol has a value other than -1 or 0, it shall have the
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value 200112L.
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.TP 7
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_POSIX_THREAD_PRIORITY_SCHEDULING
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.sp
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The implementation supports the Thread Execution Scheduling option.
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If this symbol has a value other than -1 or 0, it shall have
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the value 200112L.
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.TP 7
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_POSIX_THREAD_PROCESS_SHARED
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.sp
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The implementation supports the Thread Process-Shared Synchronization
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option. If this symbol has a value other than -1 or 0, it
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shall have the value 200112L.
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.TP 7
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_POSIX_THREAD_SAFE_FUNCTIONS
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.sp
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The implementation supports the Thread-Safe Functions option. If this
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symbol has a value other than -1 or 0, it shall have the
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value 200112L.
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.TP 7
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_POSIX_THREAD_SPORADIC_SERVER
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.sp
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The implementation supports the Thread Sporadic Server option. If
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this symbol has a value other than -1 or 0, it shall have the
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value 200112L.
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.TP 7
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_POSIX_THREADS
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.sp
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The implementation supports the Threads option. If this symbol has
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a value other than -1 or 0, it shall have the value 200112L.
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.TP 7
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_POSIX_TIMEOUTS
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.sp
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The implementation supports the Timeouts option. If this symbol has
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a value other than -1 or 0, it shall have the value 200112L.
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.TP 7
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_POSIX_TIMERS
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.sp
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The implementation supports the Timers option. If this symbol has
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a value other than -1 or 0, it shall have the value 200112L.
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.TP 7
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_POSIX_TRACE
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.sp
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The implementation supports the Trace option. If this symbol has a
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value other than -1 or 0, it shall have the value 200112L.
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.TP 7
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_POSIX_TRACE_EVENT_FILTER
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.sp
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The implementation supports the Trace Event Filter option. If this
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symbol has a value other than -1 or 0, it shall have the value
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200112L.
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.TP 7
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_POSIX_TRACE_INHERIT
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.sp
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The implementation supports the Trace Inherit option. If this symbol
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has a value other than -1 or 0, it shall have the value
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200112L.
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.TP 7
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_POSIX_TRACE_LOG
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.sp
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The implementation supports the Trace Log option. If this symbol has
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a value other than -1 or 0, it shall have the value 200112L.
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.TP 7
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_POSIX_TYPED_MEMORY_OBJECTS
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.sp
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The implementation supports the Typed Memory Objects option. If this
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symbol has a value other than -1 or 0, it shall have the value
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200112L.
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.TP 7
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_POSIX_VDISABLE
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This symbol shall be defined to be the value of a character that shall
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disable terminal special character handling as described in
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\fI<termios.h>\fP . This symbol shall always be set to a value other
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than -1.
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.TP 7
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_POSIX2_C_BIND
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The implementation supports the C-Language Binding option. This symbol
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shall always have the value 200112L.
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.TP 7
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_POSIX2_C_DEV
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.sp
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The implementation supports the C-Language Development Utilities option.
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If this symbol has a value other than -1 or 0, it shall
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have the value 200112L.
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.TP 7
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_POSIX2_CHAR_TERM
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The implementation supports at least one terminal type.
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.TP 7
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_POSIX2_FORT_DEV
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.sp
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The implementation supports the FORTRAN Development Utilities option.
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If this symbol has a value other than -1 or 0, it shall have
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the value 200112L.
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.TP 7
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_POSIX2_FORT_RUN
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.sp
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The implementation supports the FORTRAN Runtime Utilities option.
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If this symbol has a value other than -1 or 0, it shall have the
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value 200112L.
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.TP 7
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_POSIX2_LOCALEDEF
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The implementation supports the creation of locales by the \fIlocaledef\fP
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utility. If
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this symbol has a value other than -1 or 0, it shall have the value
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200112L.
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.TP 7
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_POSIX2_PBS
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.sp
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The implementation supports the Batch Environment Services and Utilities
|
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option. If this symbol has a value other than -1 or 0, it
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shall have the value 200112L.
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.TP 7
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|
_POSIX2_PBS_ACCOUNTING
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.sp
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The implementation supports the Batch Accounting option. If this symbol
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has a value other than -1 or 0, it shall have the value
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200112L.
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.TP 7
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|
_POSIX2_PBS_CHECKPOINT
|
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.sp
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The implementation supports the Batch Checkpoint/Restart option. If
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this symbol has a value other than -1 or 0, it shall have the
|
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value 200112L.
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.TP 7
|
|
_POSIX2_PBS_LOCATE
|
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.sp
|
|
The implementation supports the Locate Batch Job Request option. If
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this symbol has a value other than -1 or 0, it shall have the
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value 200112L.
|
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.TP 7
|
|
_POSIX2_PBS_MESSAGE
|
|
.sp
|
|
The implementation supports the Batch Job Message Request option.
|
|
If this symbol has a value other than -1 or 0, it shall have the
|
|
value 200112L.
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.TP 7
|
|
_POSIX2_PBS_TRACK
|
|
.sp
|
|
The implementation supports the Track Batch Job Request option. If
|
|
this symbol has a value other than -1 or 0, it shall have the
|
|
value 200112L.
|
|
.TP 7
|
|
_POSIX2_SW_DEV
|
|
.sp
|
|
The implementation supports the Software Development Utilities option.
|
|
If this symbol has a value other than -1 or 0, it shall have
|
|
the value 200112L.
|
|
.TP 7
|
|
_POSIX2_UPE
|
|
.sp
|
|
The implementation supports the User Portability Utilities option.
|
|
If this symbol has a value other than -1 or 0, it shall have the
|
|
value 200112L.
|
|
.TP 7
|
|
_V6_ILP32_OFF32
|
|
The implementation provides a C-language compilation environment with
|
|
32-bit \fBint\fP, \fBlong\fP, \fBpointer\fP, and
|
|
\fBoff_t\fP types.
|
|
.TP 7
|
|
_V6_ILP32_OFFBIG
|
|
The implementation provides a C-language compilation environment with
|
|
32-bit \fBint\fP, \fBlong\fP, and \fBpointer\fP types and
|
|
an \fBoff_t\fP type using at least 64 bits.
|
|
.TP 7
|
|
_V6_LP64_OFF64
|
|
The implementation provides a C-language compilation environment with
|
|
32-bit \fBint\fP and 64-bit \fBlong\fP, \fBpointer\fP, and
|
|
\fBoff_t\fP types.
|
|
.TP 7
|
|
_V6_LPBIG_OFFBIG
|
|
The implementation provides a C-language compilation environment with
|
|
an \fBint\fP type using at least 32 bits and \fBlong\fP,
|
|
\fBpointer\fP, and \fBoff_t\fP types using at least 64 bits.
|
|
.TP 7
|
|
_XBS5_ILP32_OFF32 (\fBLEGACY\fP)
|
|
.sp
|
|
The implementation provides a C-language compilation environment with
|
|
32-bit \fBint\fP, \fBlong\fP, \fBpointer\fP, and
|
|
\fBoff_t\fP types.
|
|
.TP 7
|
|
_XBS5_ILP32_OFFBIG (\fBLEGACY\fP)
|
|
.sp
|
|
The implementation provides a C-language compilation environment with
|
|
32-bit \fBint\fP, \fBlong\fP, and \fBpointer\fP types and
|
|
an \fBoff_t\fP type using at least 64 bits.
|
|
.TP 7
|
|
_XBS5_LP64_OFF64 (\fBLEGACY\fP)
|
|
.sp
|
|
The implementation provides a C-language compilation environment with
|
|
32-bit \fBint\fP and 64-bit \fBlong\fP, \fBpointer\fP, and
|
|
\fBoff_t\fP types.
|
|
.TP 7
|
|
_XBS5_LPBIG_OFFBIG (\fBLEGACY\fP)
|
|
.sp
|
|
The implementation provides a C-language compilation environment with
|
|
an \fBint\fP type using at least 32 bits and \fBlong\fP,
|
|
\fBpointer\fP, and \fBoff_t\fP types using at least 64 bits.
|
|
.TP 7
|
|
_XOPEN_CRYPT
|
|
.sp
|
|
The implementation supports the X/Open Encryption Option Group.
|
|
.TP 7
|
|
_XOPEN_ENH_I18N
|
|
The implementation supports the Issue 4, Version 2 Enhanced Internationalization
|
|
Option Group. This symbol shall always be set to a
|
|
value other than -1.
|
|
.TP 7
|
|
_XOPEN_LEGACY
|
|
The implementation supports the Legacy Option Group.
|
|
.TP 7
|
|
_XOPEN_REALTIME
|
|
The implementation supports the X/Open Realtime Option Group.
|
|
.TP 7
|
|
_XOPEN_REALTIME_THREADS
|
|
The implementation supports the X/Open Realtime Threads Option Group.
|
|
.TP 7
|
|
_XOPEN_SHM
|
|
The implementation supports the Issue 4, Version 2 Shared Memory Option
|
|
Group. This symbol shall always be set to a value other
|
|
than -1.
|
|
.TP 7
|
|
_XOPEN_STREAMS
|
|
The implementation supports the XSI STREAMS Option Group.
|
|
.TP 7
|
|
_XOPEN_UNIX
|
|
.sp
|
|
The implementation supports the XSI extension.
|
|
.sp
|
|
.SS Execution-Time Symbolic Constants
|
|
.LP
|
|
If any of the following constants are not defined in the \fI<unistd.h>\fP
|
|
header, the value shall vary depending on the
|
|
file to which it is applied.
|
|
.LP
|
|
If any of the following constants are defined to have value -1 in
|
|
the \fI<unistd.h>\fP header, the implementation shall
|
|
not provide the option on any file; if any are defined to have a value
|
|
other than -1 in the \fI<unistd.h>\fP header, the
|
|
implementation shall provide the option on all applicable files.
|
|
.LP
|
|
All of the following constants, whether defined in \fI<unistd.h>\fP
|
|
or not, may be queried with respect to a specific
|
|
file using the \fIpathconf\fP() or \fIfpathconf\fP() functions:
|
|
.TP 7
|
|
_POSIX_ASYNC_IO
|
|
Asynchronous input or output operations may be performed for the associated
|
|
file.
|
|
.TP 7
|
|
_POSIX_PRIO_IO
|
|
Prioritized input or output operations may be performed for the associated
|
|
file.
|
|
.TP 7
|
|
_POSIX_SYNC_IO
|
|
Synchronized input or output operations may be performed for the associated
|
|
file.
|
|
.sp
|
|
.SS Constants for Functions
|
|
.LP
|
|
The following symbolic constant shall be defined:
|
|
.TP 7
|
|
NULL
|
|
Null pointer
|
|
.sp
|
|
.LP
|
|
The following symbolic constants shall be defined for the \fIaccess\fP()
|
|
function:
|
|
.TP 7
|
|
F_OK
|
|
Test for existence of file.
|
|
.TP 7
|
|
R_OK
|
|
Test for read permission.
|
|
.TP 7
|
|
W_OK
|
|
Test for write permission.
|
|
.TP 7
|
|
X_OK
|
|
Test for execute (search) permission.
|
|
.sp
|
|
.LP
|
|
The constants F_OK, R_OK, W_OK, and X_OK and the expressions \fIR_OK\fP|\fIW_OK\fP,
|
|
\fIR_OK\fP|\fIX_OK\fP, and
|
|
\fIR_OK\fP|\fIW_OK\fP|\fIX_OK\fP shall all have distinct values.
|
|
.LP
|
|
The following symbolic constants shall be defined for the \fIconfstr\fP()
|
|
function:
|
|
.TP 7
|
|
_CS_PATH
|
|
This is the value for the \fIPATH\fP environment variable that finds
|
|
all standard utilities.
|
|
.TP 7
|
|
_CS_POSIX_V6_ILP32_OFF32_CFLAGS
|
|
If \fIsysconf\fP(_SC_V6_ILP32_OFF32) returns -1, the meaning of this
|
|
value is unspecified. Otherwise, this value is the set of
|
|
initial options to be given to the \fIc99\fP utility to build an application
|
|
using a
|
|
programming model with 32-bit \fBint\fP, \fBlong\fP, \fBpointer\fP,
|
|
and \fBoff_t\fP types.
|
|
.TP 7
|
|
_CS_POSIX_V6_ILP32_OFF32_LDFLAGS
|
|
If \fIsysconf\fP(_SC_V6_ILP32_OFF32) returns -1, the meaning of this
|
|
value is unspecified. Otherwise, this value is the set of
|
|
final options to be given to the \fIc99\fP utility to build an application
|
|
using a programming
|
|
model with 32-bit \fBint\fP, \fBlong\fP, \fBpointer\fP, and \fBoff_t\fP
|
|
types.
|
|
.TP 7
|
|
_CS_POSIX_V6_ILP32_OFF32_LIBS
|
|
If \fIsysconf\fP(_SC_V6_ILP32_OFF32) returns -1, the meaning of this
|
|
value is unspecified. Otherwise, this value is the set of
|
|
libraries to be given to the \fIc99\fP utility to build an application
|
|
using a programming
|
|
model with 32-bit \fBint\fP, \fBlong\fP, \fBpointer\fP, and \fBoff_t\fP
|
|
types.
|
|
.TP 7
|
|
_CS_POSIX_V6_ILP32_OFFBIG_CFLAGS
|
|
If \fIsysconf\fP(_SC_V6_ILP32_OFFBIG) returns -1, the meaning of this
|
|
value is unspecified. Otherwise, this value is the set of
|
|
initial options to be given to the \fIc99\fP utility to build an application
|
|
using a
|
|
programming model with 32-bit \fBint\fP, \fBlong\fP, and \fBpointer\fP
|
|
types, and an \fBoff_t\fP type using at least 64
|
|
bits.
|
|
.TP 7
|
|
_CS_POSIX_V6_ILP32_OFFBIG_LDFLAGS
|
|
If \fIsysconf\fP(_SC_V6_ILP32_OFFBIG) returns -1, the meaning of this
|
|
value is unspecified. Otherwise, this value is the set of
|
|
final options to be given to the \fIc99\fP utility to build an application
|
|
using a programming
|
|
model with 32-bit \fBint\fP, \fBlong\fP, and \fBpointer\fP types,
|
|
and an \fBoff_t\fP type using at least 64 bits.
|
|
.TP 7
|
|
_CS_POSIX_V6_ILP32_OFFBIG_LIBS
|
|
If \fIsysconf\fP(_SC_V6_ILP32_OFFBIG) returns -1, the meaning of this
|
|
value is unspecified. Otherwise, this value is the set of
|
|
libraries to be given to the \fIc99\fP utility to build an application
|
|
using a programming
|
|
model with 32-bit \fBint\fP, \fBlong\fP, and \fBpointer\fP types,
|
|
and an \fBoff_t\fP type using at least 64 bits.
|
|
.TP 7
|
|
_CS_POSIX_V6_LP64_OFF64_CFLAGS
|
|
If \fIsysconf\fP(_SC_V6_LP64_OFF64) returns -1, the meaning of this
|
|
value is unspecified. Otherwise, this value is the set of
|
|
initial options to be given to the \fIc99\fP utility to build an application
|
|
using a
|
|
programming model with 32-bit \fBint\fP and 64-bit \fBlong\fP, \fBpointer\fP,
|
|
and \fBoff_t\fP types.
|
|
.TP 7
|
|
_CS_POSIX_V6_LP64_OFF64_LDFLAGS
|
|
If \fIsysconf\fP(_SC_V6_LP64_OFF64) returns -1, the meaning of this
|
|
value is unspecified. Otherwise, this value is the set of
|
|
final options to be given to the \fIc99\fP utility to build an application
|
|
using a programming
|
|
model with 32-bit \fBint\fP and 64-bit \fBlong\fP, \fBpointer\fP,
|
|
and \fBoff_t\fP types.
|
|
.TP 7
|
|
_CS_POSIX_V6_LP64_OFF64_LIBS
|
|
If \fIsysconf\fP(_SC_V6_LP64_OFF64) returns -1, the meaning of this
|
|
value is unspecified. Otherwise, this value is the set of
|
|
libraries to be given to the \fIc99\fP utility to build an application
|
|
using a programming
|
|
model with 32-bit \fBint\fP and 64-bit \fBlong\fP, \fBpointer\fP,
|
|
and \fBoff_t\fP types.
|
|
.TP 7
|
|
_CS_POSIX_V6_LPBIG_OFFBIG_CFLAGS
|
|
If \fIsysconf\fP(_SC_V6_LPBIG_OFFBIG) returns -1, the meaning of this
|
|
value is unspecified. Otherwise, this value is the set of
|
|
initial options to be given to the \fIc99\fP utility to build an application
|
|
using a
|
|
programming model with an \fBint\fP type using at least 32 bits and
|
|
\fBlong\fP, \fBpointer\fP, and \fBoff_t\fP types using at
|
|
least 64 bits.
|
|
.TP 7
|
|
_CS_POSIX_V6_LPBIG_OFFBIG_LDFLAGS
|
|
If \fIsysconf\fP(_SC_V6_LPBIG_OFFBIG) returns -1, the meaning of this
|
|
value is unspecified. Otherwise, this value is the set of
|
|
final options to be given to the \fIc99\fP utility to build an application
|
|
using a programming
|
|
model with an \fBint\fP type using at least 32 bits and \fBlong\fP,
|
|
\fBpointer\fP, and \fBoff_t\fP types using at least 64
|
|
bits.
|
|
.TP 7
|
|
_CS_POSIX_V6_LPBIG_OFFBIG_LIBS
|
|
If \fIsysconf\fP(_SC_V6_LPBIG_OFFBIG) returns -1, the meaning of this
|
|
value is unspecified. Otherwise, this value is the set of
|
|
libraries to be given to the \fIc99\fP utility to build an application
|
|
using a programming
|
|
model with an \fBint\fP type using at least 32 bits and \fBlong\fP,
|
|
\fBpointer\fP, and \fBoff_t\fP types using at least 64
|
|
bits.
|
|
.TP 7
|
|
_CS_POSIX_V6_WIDTH_RESTRICTED_ENVS
|
|
This value is a <newline>-separated list of names of programming environments
|
|
supported by the implementation in which the
|
|
widths of the \fBblksize_t\fP, \fBcc_t\fP, \fBmode_t\fP, \fBnfds_t\fP,
|
|
\fBpid_t\fP, \fBptrdiff_t\fP, \fBsize_t\fP,
|
|
\fBspeed_t\fP, \fBssize_t\fP, \fBsuseconds_t\fP, \fBtcflag_t\fP, \fBuseconds_t\fP,
|
|
\fBwchar_t\fP, and \fBwint_t\fP types are
|
|
no greater than the width of type \fBlong\fP.
|
|
.sp
|
|
.LP
|
|
The following symbolic constants are reserved for compatibility with
|
|
Issue 5:
|
|
.LP
|
|
.sp
|
|
_CS_XBS5_ILP32_OFF32_CFLAGS (\fBLEGACY\fP)
|
|
.br
|
|
_CS_XBS5_ILP32_OFF32_LDFLAGS (\fBLEGACY\fP)
|
|
.br
|
|
_CS_XBS5_ILP32_OFF32_LIBS (\fBLEGACY\fP)
|
|
.br
|
|
_CS_XBS5_ILP32_OFF32_LINTFLAGS (\fBLEGACY\fP)
|
|
.br
|
|
_CS_XBS5_ILP32_OFFBIG_CFLAGS (\fBLEGACY\fP)
|
|
.br
|
|
_CS_XBS5_ILP32_OFFBIG_LDFLAGS (\fBLEGACY\fP)
|
|
.br
|
|
_CS_XBS5_ILP32_OFFBIG_LIBS (\fBLEGACY\fP)
|
|
.br
|
|
_CS_XBS5_ILP32_OFFBIG_LINTFLAGS (\fBLEGACY\fP)
|
|
.br
|
|
_CS_XBS5_LP64_OFF64_CFLAGS (\fBLEGACY\fP)
|
|
.br
|
|
_CS_XBS5_LP64_OFF64_LDFLAGS (\fBLEGACY\fP)
|
|
.br
|
|
_CS_XBS5_LP64_OFF64_LIBS (\fBLEGACY\fP)
|
|
.br
|
|
_CS_XBS5_LP64_OFF64_LINTFLAGS (\fBLEGACY\fP)
|
|
.br
|
|
_CS_XBS5_LPBIG_OFFBIG_CFLAGS (\fBLEGACY\fP)
|
|
.br
|
|
_CS_XBS5_LPBIG_OFFBIG_LDFLAGS (\fBLEGACY\fP)
|
|
.br
|
|
_CS_XBS5_LPBIG_OFFBIG_LIBS (\fBLEGACY\fP)
|
|
.br
|
|
_CS_XBS5_LPBIG_OFFBIG_LINTFLAGS (\fBLEGACY\fP)
|
|
.br
|
|
.sp
|
|
.LP
|
|
The following symbolic constants shall be defined for the \fIlseek\fP()
|
|
and \fIfcntl\fP() functions and shall have distinct values:
|
|
.TP 7
|
|
SEEK_CUR
|
|
Set file offset to current plus \fIoffset\fP.
|
|
.TP 7
|
|
SEEK_END
|
|
Set file offset to EOF plus \fIoffset\fP.
|
|
.TP 7
|
|
SEEK_SET
|
|
Set file offset to \fIoffset\fP.
|
|
.sp
|
|
.LP
|
|
The following symbolic constants shall be defined as possible values
|
|
for the \fIfunction\fP argument to the \fIlockf\fP() function:
|
|
.TP 7
|
|
F_LOCK
|
|
Lock a section for exclusive use.
|
|
.TP 7
|
|
F_TEST
|
|
Test section for locks by other processes.
|
|
.TP 7
|
|
F_TLOCK
|
|
Test and lock a section for exclusive use.
|
|
.TP 7
|
|
F_ULOCK
|
|
Unlock locked sections.
|
|
.sp
|
|
.LP
|
|
The following symbolic constants shall be defined for \fIpathconf\fP():
|
|
.LP
|
|
.sp
|
|
_PC_ALLOC_SIZE_MIN
|
|
.br
|
|
_PC_ASYNC_IO
|
|
.br
|
|
_PC_CHOWN_RESTRICTED
|
|
.br
|
|
_PC_FILESIZEBITS
|
|
.br
|
|
_PC_LINK_MAX
|
|
.br
|
|
_PC_MAX_CANON
|
|
.br
|
|
_PC_MAX_INPUT
|
|
.br
|
|
_PC_NAME_MAX
|
|
.br
|
|
_PC_NO_TRUNC
|
|
.br
|
|
_PC_PATH_MAX
|
|
.br
|
|
_PC_PIPE_BUF
|
|
.br
|
|
_PC_PRIO_IO
|
|
.br
|
|
_PC_REC_INCR_XFER_SIZE
|
|
.br
|
|
_PC_REC_MIN_XFER_SIZE
|
|
.br
|
|
_PC_REC_XFER_ALIGN
|
|
.br
|
|
_PC_SYMLINK_MAX
|
|
.br
|
|
_PC_SYNC_IO
|
|
.br
|
|
_PC_VDISABLE
|
|
.br
|
|
.LP
|
|
The following symbolic constants shall be defined for \fIsysconf\fP():
|
|
.LP
|
|
.sp
|
|
_SC_2_C_BIND
|
|
.br
|
|
_SC_2_C_DEV
|
|
.br
|
|
_SC_2_C_VERSION
|
|
.br
|
|
_SC_2_CHAR_TERM
|
|
.br
|
|
_SC_2_FORT_DEV
|
|
.br
|
|
_SC_2_FORT_RUN
|
|
.br
|
|
_SC_2_LOCALEDEF
|
|
.br
|
|
_SC_2_PBS
|
|
.br
|
|
_SC_2_PBS_ACCOUNTING
|
|
.br
|
|
_SC_2_PBS_CHECKPOINT
|
|
.br
|
|
_SC_2_PBS_LOCATE
|
|
.br
|
|
_SC_2_PBS_MESSAGE
|
|
.br
|
|
_SC_2_PBS_TRACK
|
|
.br
|
|
_SC_2_SW_DEV
|
|
.br
|
|
_SC_2_UPE
|
|
.br
|
|
_SC_2_VERSION
|
|
.br
|
|
_SC_ADVISORY_INFO
|
|
.br
|
|
_SC_ARG_MAX
|
|
.br
|
|
_SC_AIO_LISTIO_MAX
|
|
.br
|
|
_SC_AIO_MAX
|
|
.br
|
|
_SC_AIO_PRIO_DELTA_MAX
|
|
.br
|
|
_SC_ASYNCHRONOUS_IO
|
|
.br
|
|
_SC_ATEXIT_MAX
|
|
.br
|
|
_SC_BARRIERS
|
|
.br
|
|
_SC_BC_BASE_MAX
|
|
.br
|
|
_SC_BC_DIM_MAX
|
|
.br
|
|
_SC_BC_SCALE_MAX
|
|
.br
|
|
_SC_BC_STRING_MAX
|
|
.br
|
|
_SC_CHILD_MAX
|
|
.br
|
|
_SC_CLK_TCK
|
|
.br
|
|
_SC_CLOCK_SELECTION
|
|
.br
|
|
_SC_COLL_WEIGHTS_MAX
|
|
.br
|
|
_SC_CPUTIME
|
|
.br
|
|
_SC_DELAYTIMER_MAX
|
|
.br
|
|
_SC_EXPR_NEST_MAX
|
|
.br
|
|
_SC_FILE_LOCKING
|
|
.br
|
|
_SC_FSYNC
|
|
.br
|
|
_SC_GETGR_R_SIZE_MAX
|
|
.br
|
|
_SC_GETPW_R_SIZE_MAX
|
|
.br
|
|
_SC_HOST_NAME_MAX
|
|
.br
|
|
_SC_IOV_MAX
|
|
.br
|
|
_SC_IPV6
|
|
.br
|
|
_SC_JOB_CONTROL
|
|
.br
|
|
_SC_LINE_MAX
|
|
.br
|
|
_SC_LOGIN_NAME_MAX
|
|
.br
|
|
_SC_MAPPED_FILES
|
|
.br
|
|
_SC_MEMLOCK
|
|
.br
|
|
_SC_MEMLOCK_RANGE
|
|
.br
|
|
_SC_MEMORY_PROTECTION
|
|
.br
|
|
_SC_MESSAGE_PASSING
|
|
.br
|
|
_SC_MONOTONIC_CLOCK
|
|
.br
|
|
_SC_MQ_OPEN_MAX
|
|
.br
|
|
_SC_MQ_PRIO_MAX
|
|
.br
|
|
_SC_NGROUPS_MAX
|
|
.br
|
|
_SC_OPEN_MAX
|
|
.br
|
|
_SC_PAGE_SIZE
|
|
.br
|
|
_SC_PAGESIZE
|
|
.br
|
|
_SC_PRIORITIZED_IO
|
|
.br
|
|
_SC_PRIORITY_SCHEDULING
|
|
.br
|
|
_SC_RAW_SOCKETS
|
|
.br
|
|
_SC_RE_DUP_MAX
|
|
.br
|
|
_SC_READER_WRITER_LOCKS
|
|
.br
|
|
_SC_REALTIME_SIGNALS
|
|
.br
|
|
_SC_REGEXP
|
|
.br
|
|
_SC_RTSIG_MAX
|
|
.br
|
|
_SC_SAVED_IDS
|
|
.br
|
|
_SC_SEMAPHORES
|
|
.br
|
|
_SC_SEM_NSEMS_MAX
|
|
.br
|
|
_SC_SEM_VALUE_MAX
|
|
.br
|
|
_SC_SHARED_MEMORY_OBJECTS
|
|
.br
|
|
_SC_SHELL
|
|
.br
|
|
_SC_SIGQUEUE_MAX
|
|
.br
|
|
_SC_SPAWN
|
|
.br
|
|
_SC_SPIN_LOCKS
|
|
.br
|
|
_SC_SPORADIC_SERVER
|
|
.br
|
|
_SC_STREAM_MAX
|
|
.br
|
|
_SC_SYMLOOP_MAX
|
|
.br
|
|
_SC_SYNCHRONIZED_IO
|
|
.br
|
|
_SC_THREAD_ATTR_STACKADDR
|
|
.br
|
|
_SC_THREAD_ATTR_STACKSIZE
|
|
.br
|
|
_SC_THREAD_CPUTIME
|
|
.br
|
|
_SC_THREAD_DESTRUCTOR_ITERATIONS
|
|
.br
|
|
_SC_THREAD_KEYS_MAX
|
|
.br
|
|
_SC_THREAD_PRIO_INHERIT
|
|
.br
|
|
_SC_THREAD_PRIO_PROTECT
|
|
.br
|
|
_SC_THREAD_PRIORITY_SCHEDULING
|
|
.br
|
|
_SC_THREAD_PROCESS_SHARED
|
|
.br
|
|
_SC_THREAD_SAFE_FUNCTIONS
|
|
.br
|
|
_SC_THREAD_SPORADIC_SERVER
|
|
.br
|
|
_SC_THREAD_STACK_MIN
|
|
.br
|
|
_SC_THREAD_THREADS_MAX
|
|
.br
|
|
_SC_TIMEOUTS
|
|
.br
|
|
_SC_THREADS
|
|
.br
|
|
_SC_TIMER_MAX
|
|
.br
|
|
_SC_TIMERS
|
|
.br
|
|
_SC_TRACE
|
|
.br
|
|
_SC_TRACE_EVENT_FILTER
|
|
.br
|
|
_SC_TRACE_INHERIT
|
|
.br
|
|
_SC_TRACE_LOG
|
|
.br
|
|
_SC_TTY_NAME_MAX
|
|
.br
|
|
_SC_TYPED_MEMORY_OBJECTS
|
|
.br
|
|
_SC_TZNAME_MAX
|
|
.br
|
|
_SC_V6_ILP32_OFF32
|
|
.br
|
|
_SC_V6_ILP32_OFFBIG
|
|
.br
|
|
_SC_V6_LP64_OFF64
|
|
.br
|
|
_SC_V6_LPBIG_OFFBIG
|
|
.br
|
|
_SC_VERSION
|
|
.br
|
|
_SC_XBS5_ILP32_OFF32 (\fBLEGACY\fP)
|
|
.br
|
|
_SC_XBS5_ILP32_OFFBIG (\fBLEGACY\fP)
|
|
.br
|
|
_SC_XBS5_LP64_OFF64 (\fBLEGACY\fP)
|
|
.br
|
|
_SC_XBS5_LPBIG_OFFBIG (\fBLEGACY\fP)
|
|
.br
|
|
_SC_XOPEN_CRYPT
|
|
.br
|
|
_SC_XOPEN_ENH_I18N
|
|
.br
|
|
_SC_XOPEN_LEGACY
|
|
.br
|
|
_SC_XOPEN_REALTIME
|
|
.br
|
|
_SC_XOPEN_REALTIME_THREADS
|
|
.br
|
|
_SC_XOPEN_SHM
|
|
.br
|
|
_SC_XOPEN_STREAMS
|
|
.br
|
|
_SC_XOPEN_UNIX
|
|
.br
|
|
_SC_XOPEN_VERSION
|
|
.br
|
|
_SC_XOPEN_XCU_VERSION
|
|
.br
|
|
.LP
|
|
The two constants _SC_PAGESIZE and _SC_PAGE_SIZE may be defined to
|
|
have the same value.
|
|
.LP
|
|
The following symbolic constants shall be defined for file streams:
|
|
.TP 7
|
|
STDERR_FILENO
|
|
File number of \fIstderr\fP; 2.
|
|
.TP 7
|
|
STDIN_FILENO
|
|
File number of \fIstdin\fP; 0.
|
|
.TP 7
|
|
STDOUT_FILENO
|
|
File number of \fIstdout\fP; 1.
|
|
.sp
|
|
.SS Type Definitions
|
|
.LP
|
|
The \fBsize_t\fP, \fBssize_t\fP, \fBuid_t\fP, \fBgid_t\fP, \fBoff_t\fP,
|
|
\fBpid_t\fP, and \fBuseconds_t\fP types shall be
|
|
defined as described in \fI<sys/types.h>\fP.
|
|
.LP
|
|
The \fBintptr_t\fP type shall be defined as described in \fI<inttypes.h>\fP.
|
|
.SS Declarations
|
|
.LP
|
|
The following shall be declared as functions and may also be defined
|
|
as macros. Function prototypes shall be provided.
|
|
.sp
|
|
.RS
|
|
.nf
|
|
|
|
\fBint access(const char *, int);
|
|
unsigned alarm(unsigned);
|
|
int chdir(const char *);
|
|
int chown(const char *, uid_t, gid_t);
|
|
int close(int);
|
|
size_t confstr(int, char *, size_t);
|
|
.sp
|
|
|
|
|
|
char *crypt(const char *, const char *);
|
|
char *ctermid(char *);
|
|
|
|
int dup(int);
|
|
.sp
|
|
|
|
int dup2(int, int);
|
|
|
|
void encrypt(char[64], int);
|
|
|
|
int execl(const char *, const char *, ...);
|
|
int execle(const char *, const char *, ...);
|
|
int execlp(const char *, const char *, ...);
|
|
int execv(const char *, char *const []);
|
|
int execve(const char *, char *const [], char *const []);
|
|
int execvp(const char *, char *const []);
|
|
void _exit(int);
|
|
int fchown(int, uid_t, gid_t);
|
|
|
|
int fchdir(int);
|
|
|
|
|
|
int fdatasync(int);
|
|
|
|
pid_t fork(void);
|
|
long fpathconf(int, int);
|
|
|
|
int fsync(int);
|
|
|
|
int ftruncate(int, off_t);
|
|
char *getcwd(char *, size_t);
|
|
gid_t getegid(void);
|
|
uid_t geteuid(void);
|
|
gid_t getgid(void);
|
|
int getgroups(int, gid_t []);
|
|
|
|
long gethostid(void);
|
|
|
|
int gethostname(char *, size_t);
|
|
char *getlogin(void);
|
|
int getlogin_r(char *, size_t);
|
|
int getopt(int, char * const [], const char *);
|
|
|
|
pid_t getpgid(pid_t);
|
|
|
|
pid_t getpgrp(void);
|
|
pid_t getpid(void);
|
|
pid_t getppid(void);
|
|
|
|
pid_t getsid(pid_t);
|
|
|
|
uid_t getuid(void);
|
|
|
|
char *getwd(char *); (\fP\fBLEGACY\fP \fB)
|
|
|
|
int isatty(int);
|
|
|
|
int lchown(const char *, uid_t, gid_t);
|
|
|
|
int link(const char *, const char *);
|
|
|
|
int lockf(int, int, off_t);
|
|
|
|
off_t lseek(int, off_t, int);
|
|
|
|
int nice(int);
|
|
|
|
long pathconf(const char *, int);
|
|
int pause(void);
|
|
int pipe(int [2]);
|
|
|
|
ssize_t pread(int, void *, size_t, off_t);
|
|
ssize_t pwrite(int, const void *, size_t, off_t);
|
|
|
|
ssize_t read(int, void *, size_t);
|
|
ssize_t readlink(const char *restrict, char *restrict, size_t);
|
|
int rmdir(const char *);
|
|
int setegid(gid_t);
|
|
int seteuid(uid_t);
|
|
int setgid(gid_t);
|
|
.sp
|
|
|
|
int setpgid(pid_t, pid_t);
|
|
|
|
pid_t setpgrp(void);
|
|
int setregid(gid_t, gid_t);
|
|
int setreuid(uid_t, uid_t);
|
|
|
|
pid_t setsid(void);
|
|
int setuid(uid_t);
|
|
unsigned sleep(unsigned);
|
|
|
|
void swab(const void *restrict, void *restrict, ssize_t);
|
|
int symlink(const char *, const char *);
|
|
void sync(void);
|
|
|
|
long sysconf(int);
|
|
pid_t tcgetpgrp(int);
|
|
int tcsetpgrp(int, pid_t);
|
|
|
|
int truncate(const char *, off_t);
|
|
|
|
char *ttyname(int);
|
|
int ttyname_r(int, char *, size_t);
|
|
|
|
useconds_t ualarm(useconds_t, useconds_t);
|
|
|
|
int unlink(const char *);
|
|
|
|
int usleep(useconds_t);
|
|
pid_t vfork(void);
|
|
|
|
ssize_t write(int, const void *, size_t);
|
|
\fP
|
|
.fi
|
|
.RE
|
|
.LP
|
|
Implementations may also include the \fIpthread_atfork\fP() prototype
|
|
as defined
|
|
in \fI<pthread.h>\fP .
|
|
.LP
|
|
The following external variables shall be declared:
|
|
.sp
|
|
.RS
|
|
.nf
|
|
|
|
\fBextern char *optarg;
|
|
extern int optind, opterr, optopt;
|
|
\fP
|
|
.fi
|
|
.RE
|
|
.LP
|
|
\fIThe following sections are informative.\fP
|
|
.SH APPLICATION USAGE
|
|
.LP
|
|
IEEE\ Std\ 1003.1-2001 only describes the behavior of systems that
|
|
claim conformance to it. However, application
|
|
developers who want to write applications that adapt to other versions
|
|
of IEEE\ Std\ 1003.1 (or to systems that do not
|
|
conform to any POSIX standard) may find it useful to code them so
|
|
as to conditionally compile different code depending on the value
|
|
of _POSIX_VERSION, for example:
|
|
.sp
|
|
.RS
|
|
.nf
|
|
|
|
\fB#if _POSIX_VERSION >= 200112L
|
|
/* Use the newer function that copes with large files. */
|
|
off_t pos=ftello(fp);
|
|
#else
|
|
/* Either this is an old version of POSIX, or _POSIX_VERSION is
|
|
not even defined, so use the traditional function. */
|
|
long pos=ftell(fp);
|
|
#endif
|
|
\fP
|
|
.fi
|
|
.RE
|
|
.LP
|
|
Earlier versions of IEEE\ Std\ 1003.1 and of the Single UNIX Specification
|
|
can be identified by the following
|
|
macros:
|
|
.TP 7
|
|
POSIX.1-1988 standard
|
|
_POSIX_VERSION==198808L
|
|
.TP 7
|
|
POSIX.1-1990 standard
|
|
_POSIX_VERSION==199009L
|
|
.TP 7
|
|
ISO\ POSIX-1:1996 standard
|
|
_POSIX_VERSION==199506L
|
|
.TP 7
|
|
Single UNIX Specification, Version 1
|
|
_XOPEN_UNIX and _XOPEN_VERSION==4
|
|
.TP 7
|
|
Single UNIX Specification, Version 2
|
|
_XOPEN_UNIX and _XOPEN_VERSION==500
|
|
.sp
|
|
.LP
|
|
IEEE\ Std\ 1003.1-2001 does not make any attempt to define application
|
|
binary interaction with the underlying operating
|
|
system. However, application developers may find it useful to query
|
|
_SC_VERSION at runtime via \fIsysconf\fP() to determine whether the
|
|
current version of the operating system supports the
|
|
necessary functionality as in the following program fragment:
|
|
.sp
|
|
.RS
|
|
.nf
|
|
|
|
\fBif (sysconf(_SC_VERSION) < 200112L) {
|
|
fprintf(stderr, "POSIX.1-2001 system required, terminating \\n");
|
|
exit(1);
|
|
}
|
|
\fP
|
|
.fi
|
|
.RE
|
|
.LP
|
|
New applications should not use _XOPEN_SHM or _XOPEN_ENH_I18N.
|
|
.SH RATIONALE
|
|
.LP
|
|
As IEEE\ Std\ 1003.1-2001 evolved, certain options became sufficiently
|
|
standardized that it was concluded that simply
|
|
requiring one of the option choices was simpler than retaining the
|
|
option. However, for backwards-compatibility, the option flags
|
|
(with required constant values) are retained.
|
|
.SS Version Test Macros
|
|
.LP
|
|
The standard developers considered altering the definition of _POSIX_VERSION
|
|
and removing _SC_VERSION from the specification of
|
|
\fIsysconf\fP() since the utility to an application was deemed by
|
|
some to be minimal, and
|
|
since the implementation of the functionality is potentially problematic.
|
|
However, they recognized that support for existing
|
|
application binaries is a concern to manufacturers, application developers,
|
|
and the users of implementations conforming to
|
|
IEEE\ Std\ 1003.1-2001.
|
|
.LP
|
|
While the example using _SC_VERSION in the APPLICATION USAGE section
|
|
does not provide the greatest degree of imaginable utility
|
|
to the application developer or user, it is arguably better than a
|
|
\fBcore\fP file or some other equally obscure result. (It is
|
|
also possible for implementations to encode and recognize application
|
|
binaries compiled in various POSIX.1-conforming environments,
|
|
and modify the semantics of the underlying system to conform to the
|
|
expectations of the application.) For the reasons outlined in
|
|
the preceding paragraphs and in the APPLICATION USAGE section, the
|
|
standard developers elected to retain the _POSIX_VERSION and
|
|
_SC_VERSION functionality.
|
|
.SS Compile-Time Symbolic Constants for System-Wide Options
|
|
.LP
|
|
IEEE\ Std\ 1003.1-2001 now includes support in certain areas for the
|
|
newly adopted policy governing options and
|
|
stubs.
|
|
.LP
|
|
This policy provides flexibility for implementations in how they support
|
|
options. It also specifies how conforming applications
|
|
can adapt to different implementations that support different sets
|
|
of options. It allows the following:
|
|
.IP " 1." 4
|
|
If an implementation has no interest in supporting an option, it does
|
|
not have to provide anything associated with that option
|
|
beyond the announcement that it does not support it.
|
|
.LP
|
|
.IP " 2." 4
|
|
An implementation can support a partial or incompatible version of
|
|
an option (as a non-standard extension) as long as it does
|
|
not claim to support the option.
|
|
.LP
|
|
.IP " 3." 4
|
|
An application can determine whether the option is supported. A strictly
|
|
conforming application must check this announcement
|
|
mechanism before first using anything associated with the option.
|
|
.LP
|
|
.LP
|
|
There is an important implication of this policy. IEEE\ Std\ 1003.1-2001
|
|
cannot dictate the behavior of interfaces
|
|
associated with an option when the implementation does not claim to
|
|
support the option. In particular, it cannot require that a
|
|
function associated with an unsupported option will fail if it does
|
|
not perform as specified. However, this policy does not prevent
|
|
a standard from requiring certain functions to always be present,
|
|
but that they shall always fail on some implementations. The \fIsetpgid\fP()
|
|
function in the POSIX.1-1990 standard, for example, is considered
|
|
appropriate.
|
|
.LP
|
|
The POSIX standards include various options, and the C-language binding
|
|
support for an option implies that the implementation
|
|
must supply data types and function interfaces. An application must
|
|
be able to discover whether the implementation supports each
|
|
option.
|
|
.LP
|
|
Any application must consider the following three cases for each option:
|
|
.IP " 1." 4
|
|
Option never supported.
|
|
.LP
|
|
The implementation advertises at compile time that the option will
|
|
never be supported. In this case, it is not necessary for the
|
|
implementation to supply any of the data types or function interfaces
|
|
that are provided only as part of the option. The
|
|
implementation might provide data types and functions that are similar
|
|
to those defined by IEEE\ Std\ 1003.1-2001, but
|
|
there is no guarantee for any particular behavior.
|
|
.LP
|
|
.IP " 2." 4
|
|
Option always supported.
|
|
.LP
|
|
The implementation advertises at compile time that the option will
|
|
always be supported. In this case, all data types and
|
|
function interfaces shall be available and shall operate as specified.
|
|
.LP
|
|
.IP " 3." 4
|
|
Option might or might not be supported.
|
|
.LP
|
|
Some implementations might not provide a mechanism to specify support
|
|
of options at compile time. In addition, the
|
|
implementation might be unable or unwilling to specify support or
|
|
non-support at compile time. In either case, any application that
|
|
might use the option at runtime must be able to compile and execute.
|
|
The implementation must provide, at compile time, all data
|
|
types and function interfaces that are necessary to allow this. In
|
|
this situation, there must be a mechanism that allows the
|
|
application to query, at runtime, whether the option is supported.
|
|
If the application attempts to use the option when it is not
|
|
supported, the result is unspecified unless explicitly specified otherwise
|
|
in IEEE\ Std\ 1003.1-2001.
|
|
.LP
|
|
.SH FUTURE DIRECTIONS
|
|
.LP
|
|
None.
|
|
.SH SEE ALSO
|
|
.LP
|
|
\fI<inttypes.h>\fP , \fI<limits.h>\fP , \fI<sys/socket.h>\fP , \fI<sys/types.h>\fP
|
|
, \fI<termios.h>\fP , \fI<wctype.h>\fP , the System Interfaces volume
|
|
of IEEE\ Std\ 1003.1-2001, \fIaccess\fP(), \fIalarm\fP(), \fIchdir\fP(),
|
|
\fIchown\fP(), \fIclose\fP(), \fIcrypt\fP(), \fIctermid\fP(), \fIdup\fP(),
|
|
\fIencrypt\fP(), \fIenviron\fP, \fIexec\fP, \fIexit\fP(), \fIfchdir\fP(),
|
|
\fIfchown\fP(), \fIfcntl\fP(), \fIfork\fP(), \fIfpathconf\fP(), \fIfsync\fP(),
|
|
\fIftruncate\fP(), \fIgetcwd\fP(), \fIgetegid\fP(), \fIgeteuid\fP(),
|
|
\fIgetgid\fP(), \fIgetgroups\fP(), \fIgethostid\fP(), \fIgethostname\fP(),
|
|
\fIgetlogin\fP(), \fIgetpgid\fP(), \fIgetpgrp\fP(), \fIgetpid\fP(),
|
|
\fIgetppid\fP(), \fIgetsid\fP(), \fIgetuid\fP(), \fIisatty\fP(), \fIlchown\fP(),
|
|
\fIlink\fP(), \fIlockf\fP(), \fIlseek\fP(), \fInice\fP(), \fIpathconf\fP(),
|
|
\fIpause\fP(), \fIpipe\fP(), \fIread\fP(), \fIreadlink\fP(), \fIrmdir\fP(),
|
|
\fIsetgid\fP(), \fIsetpgid\fP(), \fIsetpgrp\fP(), \fIsetregid\fP(),
|
|
\fIsetreuid\fP(), \fIsetsid\fP(), \fIsetuid\fP(), \fIsleep\fP(), \fIswab\fP(),
|
|
\fIsymlink\fP(), \fIsync\fP(), \fIsysconf\fP(), \fItcgetpgrp\fP(),
|
|
\fItcsetpgrp\fP(), \fItruncate\fP(), \fIttyname\fP(), \fIualarm\fP(),
|
|
\fIunlink\fP(), \fIusleep\fP(), \fIvfork\fP(), \fIwrite\fP()
|
|
.SH COPYRIGHT
|
|
Portions of this text are reprinted and reproduced in electronic form
|
|
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
|
|
-- Portable Operating System Interface (POSIX), The Open Group Base
|
|
Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
|
|
Electrical and Electronics Engineers, Inc and The Open Group. In the
|
|
event of any discrepancy between this version and the original IEEE and
|
|
The Open Group Standard, the original IEEE and The Open Group Standard
|
|
is the referee document. The original Standard can be obtained online at
|
|
http://www.opengroup.org/unix/online.html .
|