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   unistd.h.0p    ( 10 )

стандартные символьные константы и типы (standard symbolic constants and types)

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Описание (Description)

The <unistd.h> header defines miscellaneous symbolic constants
       and types, and declares miscellaneous functions. The actual
       values of the constants are unspecified except as shown. The
       contents of this header are shown below.

Version Test Macros The <unistd.h> header shall define the following symbolic constants. The values shall be suitable for use in #if preprocessing directives.

_POSIX_VERSION Integer value indicating version of this standard (C- language binding) to which the implementation conforms. For implementations conforming to POSIX.1‐2008, the value shall be 200809L.

_POSIX2_VERSION Integer value indicating version of the Shell and Utilities volume of POSIX.1 to which the implementation conforms. For implementations conforming to POSIX.1‐2008, the value shall be 200809L. For profile implementations that define _POSIX_SUBPROFILE (see Section 2.1.5.1, Subprofiling Considerations) in <unistd.h>, _POSIX2_VERSION may be left undefined or be defined with the value -1 to indicate that the Shell and Utilities volume of POSIX.1 is not supported. In this case, a call to sysconf(_SC_2_VERSION) shall return either 200809L or -1 indicating that the Shell and Utilities volume of POSIX.1 is or is not, respectively, supported at runtime.

The <unistd.h> header shall define the following symbolic constant only if the implementation supports the XSI option; see Section 2.1.4, XSI Conformance. If defined, its value shall be suitable for use in #if preprocessing directives.

_XOPEN_VERSION Integer value indicating version of the X/Open Portability Guide to which the implementation conforms. The value shall be 700.

Constants for Options and Option Groups The following symbolic constants, if defined in <unistd.h>, shall have a value of -1, 0, or greater, unless otherwise specified below. For profile implementations that define _POSIX_SUBPROFILE (see Section 2.1.5.1, Subprofiling Considerations) in <unistd.h>, constants described below as always having a value greater than zero need not be defined and, if defined, may have a value of -1, 0, or greater. The values shall be suitable for use in #if preprocessing directives.

If a symbolic constant is not defined or is defined with the value -1, the option is not supported for compilation. If it is defined with a value greater than zero, the option shall always be supported when the application is executed. If it is defined with the value zero, the option shall be supported for compilation and might or might not be supported at runtime. See Section 2.1.6, Options for further information about the conformance requirements of these three categories of support.

_POSIX_ADVISORY_INFO The implementation supports the Advisory Information option. If this symbol is defined in <unistd.h>, it shall be defined to be -1, 0, or 200809L. The value of this symbol reported by sysconf() shall either be -1 or 200809L.

_POSIX_ASYNCHRONOUS_IO The implementation supports asynchronous input and output. This symbol shall always be set to the value 200809L.

_POSIX_BARRIERS The implementation supports barriers. This symbol shall always be set to the value 200809L.

_POSIX_CHOWN_RESTRICTED The use of chown() and fchown() is restricted to a process with appropriate privileges, and to changing the group ID of a file only to the effective group ID of the process or to one of its supplementary group IDs. This symbol shall be defined with a value other than -1.

_POSIX_CLOCK_SELECTION The implementation supports clock selection. This symbol shall always be set to the value 200809L.

_POSIX_CPUTIME The implementation supports the Process CPU-Time Clocks option. If this symbol is defined in <unistd.h>, it shall be defined to be -1, 0, or 200809L. The value of this symbol reported by sysconf() shall either be -1 or 200809L.

_POSIX_FSYNC The implementation supports the File Synchronization option. If this symbol is defined in <unistd.h>, it shall be defined to be -1, 0, or 200809L. The value of this symbol reported by sysconf() shall either be -1 or 200809L.

_POSIX_IPV6 The implementation supports the IPv6 option. If this symbol is defined in <unistd.h>, it shall be defined to be -1, 0, or 200809L. The value of this symbol reported by sysconf() shall either be -1 or 200809L.

_POSIX_JOB_CONTROL The implementation supports job control. This symbol shall always be set to a value greater than zero.

_POSIX_MAPPED_FILES The implementation supports memory mapped Files. This symbol shall always be set to the value 200809L.

_POSIX_MEMLOCK The implementation supports the Process Memory Locking option. If this symbol is defined in <unistd.h>, it shall be defined to be -1, 0, or 200809L. The value of this symbol reported by sysconf() shall either be -1 or 200809L.

_POSIX_MEMLOCK_RANGE The implementation supports the Range Memory Locking option. If this symbol is defined in <unistd.h>, it shall be defined to be -1, 0, or 200809L. The value of this symbol reported by sysconf() shall either be -1 or 200809L.

_POSIX_MEMORY_PROTECTION The implementation supports memory protection. This symbol shall always be set to the value 200809L.

_POSIX_MESSAGE_PASSING The implementation supports the Message Passing option. If this symbol is defined in <unistd.h>, it shall be defined to be -1, 0, or 200809L. The value of this symbol reported by sysconf() shall either be -1 or 200809L.

_POSIX_MONOTONIC_CLOCK The implementation supports the Monotonic Clock option. If this symbol is defined in <unistd.h>, it shall be defined to be -1, 0, or 200809L. The value of this symbol reported by sysconf() shall either be -1 or 200809L.

_POSIX_NO_TRUNC Pathname components longer than {NAME_MAX} generate an error. This symbol shall be defined with a value other than -1.

_POSIX_PRIORITIZED_IO The implementation supports the Prioritized Input and Output option. If this symbol is defined in <unistd.h>, it shall be defined to be -1, 0, or 200809L. The value of this symbol reported by sysconf() shall either be -1 or 200809L.

_POSIX_PRIORITY_SCHEDULING The implementation supports the Process Scheduling option. If this symbol is defined in <unistd.h>, it shall be defined to be -1, 0, or 200809L. The value of this symbol reported by sysconf() shall either be -1 or 200809L.

_POSIX_RAW_SOCKETS The implementation supports the Raw Sockets option. If this symbol is defined in <unistd.h>, it shall be defined to be -1, 0, or 200809L. The value of this symbol reported by sysconf() shall either be -1 or 200809L.

_POSIX_READER_WRITER_LOCKS The implementation supports read-write locks. This symbol shall always be set to the value 200809L.

_POSIX_REALTIME_SIGNALS The implementation supports realtime signals. This symbol shall always be set to the value 200809L.

_POSIX_REGEXP The implementation supports the Regular Expression Handling option. This symbol shall always be set to a value greater than zero.

_POSIX_SAVED_IDS Each process has a saved set-user-ID and a saved set-group- ID. This symbol shall always be set to a value greater than zero.

_POSIX_SEMAPHORES The implementation supports semaphores. This symbol shall always be set to the value 200809L.

_POSIX_SHARED_MEMORY_OBJECTS The implementation supports the Shared Memory Objects option. If this symbol is defined in <unistd.h>, it shall be defined to be -1, 0, or 200809L. The value of this symbol reported by sysconf() shall either be -1 or 200809L.

_POSIX_SHELL The implementation supports the POSIX shell. This symbol shall always be set to a value greater than zero.

_POSIX_SPAWN The implementation supports the Spawn option. If this symbol is defined in <unistd.h>, it shall be defined to be -1, 0, or 200809L. The value of this symbol reported by sysconf() shall either be -1 or 200809L.

_POSIX_SPIN_LOCKS The implementation supports spin locks. This symbol shall always be set to the value 200809L.

_POSIX_SPORADIC_SERVER The implementation supports the Process Sporadic Server option. If this symbol is defined in <unistd.h>, it shall be defined to be -1, 0, or 200809L. The value of this symbol reported by sysconf() shall either be -1 or 200809L.

_POSIX_SYNCHRONIZED_IO The implementation supports the Synchronized Input and Output option. If this symbol is defined in <unistd.h>, it shall be defined to be -1, 0, or 200809L. The value of this symbol reported by sysconf() shall either be -1 or 200809L.

_POSIX_THREAD_ATTR_STACKADDR The implementation supports the Thread Stack Address Attribute option. If this symbol is defined in <unistd.h>, it shall be defined to be -1, 0, or 200809L. The value of this symbol reported by sysconf() shall either be -1 or 200809L.

_POSIX_THREAD_ATTR_STACKSIZE The implementation supports the Thread Stack Size Attribute option. If this symbol is defined in <unistd.h>, it shall be defined to be -1, 0, or 200809L. The value of this symbol reported by sysconf() shall either be -1 or 200809L.

_POSIX_THREAD_CPUTIME The implementation supports the Thread CPU-Time Clocks option. If this symbol is defined in <unistd.h>, it shall be defined to be -1, 0, or 200809L. The value of this symbol reported by sysconf() shall either be -1 or 200809L.

_POSIX_THREAD_PRIO_INHERIT The implementation supports the Non-Robust Mutex Priority Inheritance option. If this symbol is defined in <unistd.h>, it shall be defined to be -1, 0, or 200809L. The value of this symbol reported by sysconf() shall either be -1 or 200809L.

_POSIX_THREAD_PRIO_PROTECT The implementation supports the Non-Robust Mutex Priority Protection option. If this symbol is defined in <unistd.h>, it shall be defined to be -1, 0, or 200809L. The value of this symbol reported by sysconf() shall either be -1 or 200809L.

_POSIX_THREAD_PRIORITY_SCHEDULING The implementation supports the Thread Execution Scheduling option. If this symbol is defined in <unistd.h>, it shall be defined to be -1, 0, or 200809L. The value of this symbol reported by sysconf() shall either be -1 or 200809L.

_POSIX_THREAD_PROCESS_SHARED The implementation supports the Thread Process-Shared Synchronization option. If this symbol is defined in <unistd.h>, it shall be defined to be -1, 0, or 200809L. The value of this symbol reported by sysconf() shall either be -1 or 200809L.

_POSIX_THREAD_ROBUST_PRIO_INHERIT The implementation supports the Robust Mutex Priority Inheritance option. If this symbol is defined in <unistd.h>, it shall be defined to be -1, 0, or 200809L. The value of this symbol reported by sysconf() shall either be -1 or 200809L.

_POSIX_THREAD_ROBUST_PRIO_PROTECT The implementation supports the Robust Mutex Priority Protection option. If this symbol is defined in <unistd.h>, it shall be defined to be -1, 0, or 200809L. The value of this symbol reported by sysconf() shall either be -1 or 200809L.

_POSIX_THREAD_SAFE_FUNCTIONS The implementation supports thread-safe functions. This symbol shall always be set to the value 200809L.

_POSIX_THREAD_SPORADIC_SERVER The implementation supports the Thread Sporadic Server option. If this symbol is defined in <unistd.h>, it shall be defined to be -1, 0, or 200809L. The value of this symbol reported by sysconf() shall either be -1 or 200809L.

_POSIX_THREADS The implementation supports threads. This symbol shall always be set to the value 200809L.

_POSIX_TIMEOUTS The implementation supports timeouts. This symbol shall always be set to the value 200809L.

_POSIX_TIMERS The implementation supports timers. This symbol shall always be set to the value 200809L.

_POSIX_TRACE The implementation supports the Trace option. If this symbol is defined in <unistd.h>, it shall be defined to be -1, 0, or 200809L. The value of this symbol reported by sysconf() shall either be -1 or 200809L.

_POSIX_TRACE_EVENT_FILTER The implementation supports the Trace Event Filter option. If this symbol is defined in <unistd.h>, it shall be defined to be -1, 0, or 200809L. The value of this symbol reported by sysconf() shall either be -1 or 200809L.

_POSIX_TRACE_INHERIT The implementation supports the Trace Inherit option. If this symbol is defined in <unistd.h>, it shall be defined to be -1, 0, or 200809L. The value of this symbol reported by sysconf() shall either be -1 or 200809L.

_POSIX_TRACE_LOG The implementation supports the Trace Log option. If this symbol is defined in <unistd.h>, it shall be defined to be -1, 0, or 200809L. The value of this symbol reported by sysconf() shall either be -1 or 200809L.

_POSIX_TYPED_MEMORY_OBJECTS The implementation supports the Typed Memory Objects option. If this symbol is defined in <unistd.h>, it shall be defined to be -1, 0, or 200809L. The value of this symbol reported by sysconf() shall either be -1 or 200809L.

_POSIX_V6_ILP32_OFF32 The implementation provides a C-language compilation environment with 32-bit int, long, pointer, and off_t types.

_POSIX_V6_ILP32_OFFBIG The implementation provides a C-language compilation environment with 32-bit int, long, and pointer types and an off_t type using at least 64 bits.

_POSIX_V6_LP64_OFF64 The implementation provides a C-language compilation environment with 32-bit int and 64-bit long, pointer, and off_t types.

_POSIX_V6_LPBIG_OFFBIG The implementation provides a C-language compilation environment with an int type using at least 32 bits and long, pointer, and off_t types using at least 64 bits.

_POSIX_V7_ILP32_OFF32 The implementation provides a C-language compilation environment with 32-bit int, long, pointer, and off_t types.

_POSIX_V7_ILP32_OFFBIG The implementation provides a C-language compilation environment with 32-bit int, long, and pointer types and an off_t type using at least 64 bits.

_POSIX_V7_LP64_OFF64 The implementation provides a C-language compilation environment with 32-bit int and 64-bit long, pointer, and off_t types.

_POSIX_V7_LPBIG_OFFBIG The implementation provides a C-language compilation environment with an int type using at least 32 bits and long, pointer, and off_t types using at least 64 bits.

_POSIX2_C_BIND The implementation supports the C-Language Binding option. This symbol shall always have the value 200809L.

_POSIX2_C_DEV The implementation supports the C-Language Development Utilities option. If this symbol is defined in <unistd.h>, it shall be defined to be -1, 0, or 200809L. The value of this symbol reported by sysconf() shall either be -1 or 200809L.

_POSIX2_CHAR_TERM The implementation supports the Terminal Characteristics option. The value of this symbol reported by sysconf() shall either be -1 or a value greater than zero.

_POSIX2_FORT_DEV The implementation supports the FORTRAN Development Utilities option. If this symbol is defined in <unistd.h>, it shall be defined to be -1, 0, or 200809L. The value of this symbol reported by sysconf() shall either be -1 or 200809L.

_POSIX2_FORT_RUN The implementation supports the FORTRAN Runtime Utilities option. If this symbol is defined in <unistd.h>, it shall be defined to be -1, 0, or 200809L. The value of this symbol reported by sysconf() shall either be -1 or 200809L.

_POSIX2_LOCALEDEF The implementation supports the creation of locales by the localedef utility. If this symbol is defined in <unistd.h>, it shall be defined to be -1, 0, or 200809L. The value of this symbol reported by sysconf() shall either be -1 or 200809L.

_POSIX2_PBS The implementation supports the Batch Environment Services and Utilities option. If this symbol is defined in <unistd.h>, it shall be defined to be -1, 0, or 200809L. The value of this symbol reported by sysconf() shall either be -1 or 200809L.

_POSIX2_PBS_ACCOUNTING The implementation supports the Batch Accounting option. If this symbol is defined in <unistd.h>, it shall be defined to be -1, 0, or 200809L. The value of this symbol reported by sysconf() shall either be -1 or 200809L.

_POSIX2_PBS_CHECKPOINT The implementation supports the Batch Checkpoint/Restart option. If this symbol is defined in <unistd.h>, it shall be defined to be -1, 0, or 200809L. The value of this symbol reported by sysconf() shall either be -1 or 200809L.

_POSIX2_PBS_LOCATE The implementation supports the Locate Batch Job Request option. If this symbol is defined in <unistd.h>, it shall be defined to be -1, 0, or 200809L. The value of this symbol reported by sysconf() shall either be -1 or 200809L.

_POSIX2_PBS_MESSAGE The implementation supports the Batch Job Message Request option. If this symbol is defined in <unistd.h>, it shall be defined to be -1, 0, or 200809L. The value of this symbol reported by sysconf() shall either be -1 or 200809L.

_POSIX2_PBS_TRACK The implementation supports the Track Batch Job Request option. If this symbol is defined in <unistd.h>, it shall be defined to be -1, 0, or 200809L. The value of this symbol reported by sysconf() shall either be -1 or 200809L.

_POSIX2_SW_DEV The implementation supports the Software Development Utilities option. If this symbol is defined in <unistd.h>, it shall be defined to be -1, 0, or 200809L. The value of this symbol reported by sysconf() shall either be -1 or 200809L.

_POSIX2_UPE The implementation supports the User Portability Utilities option. If this symbol is defined in <unistd.h>, it shall be defined to be -1, 0, or 200809L. The value of this symbol reported by sysconf() shall either be -1 or 200809L.

_XOPEN_CRYPT The implementation supports the X/Open Encryption Option Group.

_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.

_XOPEN_REALTIME The implementation supports the X/Open Realtime Option Group.

_XOPEN_REALTIME_THREADS The implementation supports the X/Open Realtime Threads Option Group.

_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.

_XOPEN_STREAMS The implementation supports the XSI STREAMS Option Group.

_XOPEN_UNIX The implementation supports the XSI option.

_XOPEN_UUCP The implementation supports the UUCP Utilities option. If this symbol is defined in <unistd.h>, it shall be defined to be -1, 0, or 200809L. The value of this symbol reported by sysconf() shall be either -1 or 200809L.

Execution-Time Symbolic Constants If any of the following symbolic constants are not defined in the <unistd.h> header, the value shall vary depending on the file to which it is applied. If defined, they shall have values suitable for use in #if preprocessing directives.

If any of the following symbolic constants are defined to have value -1 in the <unistd.h> header, the implementation shall not provide the option on any file; if any are defined to have a value other than -1 in the <unistd.h> header, the implementation shall provide the option on all applicable files.

All of the following values, whether defined as symbolic constants in <unistd.h> or not, may be queried with respect to a specific file using the pathconf() or fpathconf() functions:

_POSIX_ASYNC_IO Asynchronous input or output operations may be performed for the associated file.

_POSIX_PRIO_IO Prioritized input or output operations may be performed for the associated file.

_POSIX_SYNC_IO Synchronized input or output operations may be performed for the associated file.

If the following symbolic constants are defined in the <unistd.h> header, they apply to files and all paths in all file systems on the implementation:

_POSIX_TIMESTAMP_RESOLUTION The resolution in nanoseconds for all file timestamps.

_POSIX2_SYMLINKS Symbolic links can be created.

Constants for Functions The <unistd.h> header shall define NULL as described in <stddef.h>.

The <unistd.h> header shall define the following symbolic constants for use with the access() function. The values shall be suitable for use in #if preprocessing directives.

F_OK Test for existence of file.

R_OK Test for read permission.

W_OK Test for write permission.

X_OK Test for execute (search) permission.

The constants F_OK, R_OK, W_OK, and X_OK and the expressions R_OK|W_OK, R_OK|X_OK, and R_OK|W_OK|X_OK shall all have distinct values.

The <unistd.h> header shall define the following symbolic constants for the confstr() function:

_CS_PATH This is the value for the PATH environment variable that finds all of the standard utilities that are provided in a manner accessible via the exec family of functions.

_CS_POSIX_V7_ILP32_OFF32_CFLAGS If sysconf(_SC_V7_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 c99 utility to build an application using a programming model with 32-bit int, long, pointer, and off_t types.

_CS_POSIX_V7_ILP32_OFF32_LDFLAGS If sysconf(_SC_V7_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 c99 utility to build an application using a programming model with 32-bit int, long, pointer, and off_t types.

_CS_POSIX_V7_ILP32_OFF32_LIBS If sysconf(_SC_V7_ILP32_OFF32) returns -1, the meaning of this value is unspecified. Otherwise, this value is the set of libraries to be given to the c99 utility to build an application using a programming model with 32-bit int, long, pointer, and off_t types.

_CS_POSIX_V7_ILP32_OFFBIG_CFLAGS If sysconf(_SC_V7_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 c99 utility to build an application using a programming model with 32-bit int, long, and pointer types, and an off_t type using at least 64 bits.

_CS_POSIX_V7_ILP32_OFFBIG_LDFLAGS If sysconf(_SC_V7_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 c99 utility to build an application using a programming model with 32-bit int, long, and pointer types, and an off_t type using at least 64 bits.

_CS_POSIX_V7_ILP32_OFFBIG_LIBS If sysconf(_SC_V7_ILP32_OFFBIG) returns -1, the meaning of this value is unspecified. Otherwise, this value is the set of libraries to be given to the c99 utility to build an application using a programming model with 32-bit int, long, and pointer types, and an off_t type using at least 64 bits.

_CS_POSIX_V7_LP64_OFF64_CFLAGS If sysconf(_SC_V7_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 c99 utility to build an application using a programming model with 32-bit int and 64-bit long, pointer, and off_t types.

_CS_POSIX_V7_LP64_OFF64_LDFLAGS If sysconf(_SC_V7_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 c99 utility to build an application using a programming model with 32-bit int and 64-bit long, pointer, and off_t types.

_CS_POSIX_V7_LP64_OFF64_LIBS If sysconf(_SC_V7_LP64_OFF64) returns -1, the meaning of this value is unspecified. Otherwise, this value is the set of libraries to be given to the c99 utility to build an application using a programming model with 32-bit int and 64-bit long, pointer, and off_t types.

_CS_POSIX_V7_LPBIG_OFFBIG_CFLAGS If sysconf(_SC_V7_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 c99 utility to build an application using a programming model with an int type using at least 32 bits and long, pointer, and off_t types using at least 64 bits.

_CS_POSIX_V7_LPBIG_OFFBIG_LDFLAGS If sysconf(_SC_V7_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 c99 utility to build an application using a programming model with an int type using at least 32 bits and long, pointer, and off_t types using at least 64 bits.

_CS_POSIX_V7_LPBIG_OFFBIG_LIBS If sysconf(_SC_V7_LPBIG_OFFBIG) returns -1, the meaning of this value is unspecified. Otherwise, this value is the set of libraries to be given to the c99 utility to build an application using a programming model with an int type using at least 32 bits and long, pointer, and off_t types using at least 64 bits.

_CS_POSIX_V7_THREADS_CFLAGS If sysconf(_SC_POSIX_THREADS) returns -1, the meaning of this value is unspecified. Otherwise, this value is the set of initial options to be given to the c99 utility to build a multi-threaded application. These flags are in addition to those associated with any of the other _CS_POSIX_V7_*_CFLAGS values used to specify particular type size programing environments.

_CS_POSIX_V7_THREADS_LDFLAGS If sysconf(_SC_POSIX_THREADS) returns -1, the meaning of this value is unspecified. Otherwise, this value is the set of final options to be given to the c99 utility to build a multi-threaded application. These flags are in addition to those associated with any of the other _CS_POSIX_V7_*_LDFLAGS values used to specify particular type size programing environments.

_CS_POSIX_V7_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 blksize_t, cc_t, mode_t, nfds_t, pid_t, ptrdiff_t, size_t, speed_t, ssize_t, suseconds_t, tcflag_t, wchar_t, and wint_t types are no greater than the width of type long. The format of each name shall be suitable for use with the getconf -v option.

_CS_V7_ENV This is the value that provides the environment variable information (other than that provided by _CS_PATH) that is required by the implementation to create a conforming environment, as described in the implementation's conformance documentation.

The following symbolic constants are reserved for compatibility with Issue 6:

_CS_POSIX_V6_ILP32_OFF32_CFLAGS _CS_POSIX_V6_ILP32_OFF32_LDFLAGS _CS_POSIX_V6_ILP32_OFF32_LIBS _CS_POSIX_V6_ILP32_OFFBIG_CFLAGS _CS_POSIX_V6_ILP32_OFFBIG_LDFLAGS _CS_POSIX_V6_ILP32_OFFBIG_LIBS _CS_POSIX_V6_LP64_OFF64_CFLAGS _CS_POSIX_V6_LP64_OFF64_LDFLAGS _CS_POSIX_V6_LP64_OFF64_LIBS _CS_POSIX_V6_LPBIG_OFFBIG_CFLAGS _CS_POSIX_V6_LPBIG_OFFBIG_LDFLAGS _CS_POSIX_V6_LPBIG_OFFBIG_LIBS _CS_POSIX_V6_WIDTH_RESTRICTED_ENVS _CS_V6_ENV

The <unistd.h> header shall define SEEK_CUR, SEEK_END, and SEEK_SET as described in <stdio.h>.

The <unistd.h> header shall define the following symbolic constants as possible values for the function argument to the lockf() function:

F_LOCK Lock a section for exclusive use.

F_TEST Test section for locks by other processes.

F_TLOCK Test and lock a section for exclusive use.

F_ULOCK Unlock locked sections.

The <unistd.h> header shall define the following symbolic constants for pathconf():

_PC_2_SYMLINKS _PC_ALLOC_SIZE_MIN _PC_ASYNC_IO _PC_CHOWN_RESTRICTED _PC_FILESIZEBITS _PC_LINK_MAX _PC_MAX_CANON _PC_MAX_INPUT _PC_NAME_MAX _PC_NO_TRUNC _PC_PATH_MAX _PC_PIPE_BUF _PC_PRIO_IO _PC_REC_INCR_XFER_SIZE _PC_REC_MAX_XFER_SIZE _PC_REC_MIN_XFER_SIZE _PC_REC_XFER_ALIGN _PC_SYMLINK_MAX _PC_SYNC_IO _PC_TIMESTAMP_RESOLUTION _PC_VDISABLE

The <unistd.h> header shall define the following symbolic constants for sysconf():

_SC_2_C_BIND _SC_2_C_DEV _SC_2_CHAR_TERM _SC_2_FORT_DEV _SC_2_FORT_RUN _SC_2_LOCALEDEF _SC_2_PBS _SC_2_PBS_ACCOUNTING _SC_2_PBS_CHECKPOINT _SC_2_PBS_LOCATE _SC_2_PBS_MESSAGE _SC_2_PBS_TRACK _SC_2_SW_DEV _SC_2_UPE _SC_2_VERSION _SC_ADVISORY_INFO _SC_AIO_LISTIO_MAX _SC_AIO_MAX _SC_AIO_PRIO_DELTA_MAX _SC_ARG_MAX _SC_ASYNCHRONOUS_IO _SC_ATEXIT_MAX _SC_BARRIERS _SC_BC_BASE_MAX _SC_BC_DIM_MAX _SC_BC_SCALE_MAX _SC_BC_STRING_MAX _SC_CHILD_MAX _SC_CLK_TCK _SC_CLOCK_SELECTION _SC_COLL_WEIGHTS_MAX _SC_CPUTIME _SC_DELAYTIMER_MAX _SC_EXPR_NEST_MAX _SC_FSYNC _SC_GETGR_R_SIZE_MAX _SC_GETPW_R_SIZE_MAX _SC_HOST_NAME_MAX _SC_IOV_MAX _SC_IPV6 _SC_JOB_CONTROL _SC_LINE_MAX _SC_LOGIN_NAME_MAX _SC_MAPPED_FILES _SC_MEMLOCK _SC_MEMLOCK_RANGE _SC_MEMORY_PROTECTION _SC_MESSAGE_PASSING _SC_MONOTONIC_CLOCK _SC_MQ_OPEN_MAX _SC_MQ_PRIO_MAX _SC_NGROUPS_MAX _SC_OPEN_MAX _SC_PAGE_SIZE _SC_PAGESIZE _SC_PRIORITIZED_IO _SC_PRIORITY_SCHEDULING _SC_RAW_SOCKETS _SC_RE_DUP_MAX _SC_READER_WRITER_LOCKS _SC_REALTIME_SIGNALS _SC_REGEXP _SC_RTSIG_MAX _SC_SAVED_IDS _SC_SEM_NSEMS_MAX _SC_SEM_VALUE_MAX _SC_SEMAPHORES _SC_SHARED_MEMORY_OBJECTS _SC_SHELL _SC_SIGQUEUE_MAX _SC_SPAWN _SC_SPIN_LOCKS _SC_SPORADIC_SERVER _SC_SS_REPL_MAX _SC_STREAM_MAX _SC_SYMLOOP_MAX _SC_SYNCHRONIZED_IO _SC_THREAD_ATTR_STACKADDR _SC_THREAD_ATTR_STACKSIZE _SC_THREAD_CPUTIME _SC_THREAD_DESTRUCTOR_ITERATIONS _SC_THREAD_KEYS_MAX _SC_THREAD_PRIO_INHERIT _SC_THREAD_PRIO_PROTECT _SC_THREAD_PRIORITY_SCHEDULING _SC_THREAD_PROCESS_SHARED _SC_THREAD_ROBUST_PRIO_INHERIT _SC_THREAD_ROBUST_PRIO_PROTECT _SC_THREAD_SAFE_FUNCTIONS _SC_THREAD_SPORADIC_SERVER _SC_THREAD_STACK_MIN _SC_THREAD_THREADS_MAX _SC_THREADS _SC_TIMEOUTS _SC_TIMER_MAX _SC_TIMERS _SC_TRACE _SC_TRACE_EVENT_FILTER _SC_TRACE_EVENT_NAME_MAX _SC_TRACE_INHERIT _SC_TRACE_LOG _SC_TRACE_NAME_MAX _SC_TRACE_SYS_MAX _SC_TRACE_USER_EVENT_MAX _SC_TTY_NAME_MAX _SC_TYPED_MEMORY_OBJECTS _SC_TZNAME_MAX _SC_V7_ILP32_OFF32 _SC_V7_ILP32_OFFBIG _SC_V7_LP64_OFF64 _SC_V7_LPBIG_OFFBIG _SC_V6_ILP32_OFF32 _SC_V6_ILP32_OFFBIG _SC_V6_LP64_OFF64 _SC_V6_LPBIG_OFFBIG _SC_VERSION _SC_XOPEN_CRYPT _SC_XOPEN_ENH_I18N _SC_XOPEN_REALTIME _SC_XOPEN_REALTIME_THREADS _SC_XOPEN_SHM _SC_XOPEN_STREAMS _SC_XOPEN_UNIX _SC_XOPEN_UUCP _SC_XOPEN_VERSION

The two constants _SC_PAGESIZE and _SC_PAGE_SIZE may be defined to have the same value.

The <unistd.h> header shall define the following symbolic constants for file streams:

STDERR_FILENO File number of stderr; 2.

STDIN_FILENO File number of stdin; 0.

STDOUT_FILENO File number of stdout; 1.

The <unistd.h> header shall define the following symbolic constant for terminal special character handling:

_POSIX_VDISABLE This symbol shall be defined to be the value of a character that shall disable terminal special character handling as described in Section 11.2.6, Special Control Characters. This symbol shall always be set to a value other than -1.

Type Definitions The <unistd.h> header shall define the size_t, ssize_t, uid_t, gid_t, off_t, and pid_t types as described in <sys/types.h>.

The <unistd.h> header shall define the intptr_t type as described in <stdint.h>.

Declarations The following shall be declared as functions and may also be defined as macros. Function prototypes shall be provided.

int 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); char *crypt(const char *, const char *); int dup(int); int dup2(int, int); void _exit(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 []); int faccessat(int, const char *, int, int); int fchdir(int); int fchown(int, uid_t, gid_t); int fchownat(int, const char *, uid_t, gid_t, int); int fdatasync(int); int fexecve(int, char *const [], char *const []); 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); int isatty(int); int lchown(const char *, uid_t, gid_t); int link(const char *, const char *); int linkat(int, const char *, int, const char *, int); 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); ssize_t readlinkat(int, const char *restrict, char *restrict, size_t); int rmdir(const char *); int setegid(gid_t); int seteuid(uid_t); int setgid(gid_t); 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 *); int symlinkat(const char *, int, 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); int unlink(const char *); int unlinkat(int, const char *, int); ssize_t write(int, const void *, size_t);

Implementations may also include the pthread_atfork() prototype as defined in <pthread.h>. Implementations may also include the ctermid() prototype as defined in <stdio.h>.

The <unistd.h> header shall declare the following external variables:

extern char *optarg; extern int opterr, optind, optopt;

Inclusion of the <unistd.h> header may make visible all symbols from the headers <stddef.h>, <stdint.h>, and <stdio.h>.

The following sections are informative.