The C POSIX library is a specification of a C standard library for POSIX systems. It was developed at the same time as the ANSI C standard. Some effort was made to make POSIX compatible with standard C; POSIX includes additional functions to those introduced in standard C. On the other hand, the 5 headers that were added to the C standard library with C11, were not likewise included in subsequent revisions of POSIX.

It may be included in any C++ project, however the C++ standard library may have its own implementation of certain features, such as <regex> rather than <regex.h>, <thread> rather than <pthread.h>, or <semaphore> rather than <semaphore.h>.

C POSIX library header files

Header file Description First released C Standard Asynchronous input and output Issue 5 Functions for manipulating numeric IP addresses (part of Berkeley sockets) Issue 6 Verify assumptions Issue 1 ANSI (89) Complex Arithmetic, see C mathematical functions Issue 6 C99 Magic numbers for the cpio archive format Issue 3 Character typesIssue 1ANSI (89) Device control Issue 8 Allows the opening and listing of directories Issue 2 Dynamic linking Issue 5 Retrieving Error Number Issue 1 ANSI (89) Endianness operations Issue 8 File opening, locking and other operations Issue 1 Floating-Point Environment (FPE), see C mathematical functions Issue 6 C99 Floating-point types, see C data types Issue 4 ANSI (89) Message display structures Issue 4 Filename matching Issue 4 File tree traversal Issue 1 Pathname "globbing" (pattern-matching) Issue 4 User group information and control Issue 1 Codeset conversion facility Issue 4 Fixed sized integer types, see C data types Issue 5 C99 Alternative spellings, see C alternative tokens Issue 5 NA1 (95) Language information constants – builds on C localization functions Issue 2 Pathname manipulation Issue 4 Internationalization Issue 8 Implementation-defined constants, see C data types Issue 1 ANSI (89) Category macros, see C localization functions Issue 3 ANSI (89) Mathematical declarations, see C mathematical functions Issue 1 ANSI (89) String formatting of monetary units Issue 4 Message queue Issue 5 NDBM database operations Issue 4 Listing of local network interfaces Issue 6 Translating protocol and host names into numeric addresses (part of Berkeley sockets) Issue 6 Defines Internet protocol and address family (part of Berkeley sockets) Issue 6 Additional TCP control options (part of Berkeley sockets) Issue 6 Localization message catalog functions Issue 2 Asynchronous file descriptor multiplexing Issue 4 Defines an API for creating and manipulating POSIX threads Issue 5 passwd (user information) access and control Issue 1 Regular expression matching Issue 4 Execution scheduling Issue 5 Search tables Issue 1 POSIX semaphores Issue 5 Stack environment declarations Issue 1 ANSI (89) Signals, see C signal handling Issue 1 ANSI (89) Process spawning Issue 6 Alignment macros Issue 8 C11 Handle Variable Argument List Issue 4 ANSI (89) Atomic operations Issue 8 C11 Boolean type and values, see C data types Issue 6 C99 Standard type definitions, see C data types Issue 4 ANSI (89) Integer types, see C data types Issue 6 C99 Standard buffered input/output, see C file input/output Issue 1 ANSI (89) Standard library definitions, see C standard library Issue 3 ANSI (89) The noreturn macro Issue 8 C11 Several String Operations, see C string handling Issue 1 ANSI (89) Case-insensitive string comparisons Issue 4 Stream manipulation, including ioctl Issue 4 Inter-process communication (IPC) Issue 2 Memory management, including POSIX shared memory and memory mapped files Issue 4 POSIX message queues Issue 2 Resource usage, priorities, and limiting Issue 4 Synchronous I/O multiplexing Issue 6 XSI (SysV style) semaphores Issue 2 XSI (SysV style) shared memory Issue 2 Main Berkeley sockets header Issue 6 File information (stat et al.) Issue 1 File System information Issue 4 Time and date functions and structures Issue 4 File access and modification times Issue 1 Various data types used elsewhere Issue 1 Vectored I/O operations Issue 4 Unix domain sockets Issue 6 Operating system information, including uname Issue 1 Status of terminated child processes (see wait) Issue 3 System error logging Issue 4 Magic numbers for the tar archive format Issue 3 Allows terminal I/O interfaces Issue 3 Type-Generic Macros, see C mathematical functions Issue 6 C99 ISO C threads Issue 8 C11 Type-Generic Macros, see C date and time functions Issue 1 ANSI (89) Tracing of runtime behavior (DEPRECATED) Issue 6 manipulate user context (REMOVED in POSIX.1-2008) Resource limiting (DEPRECATED in favor of <sys/resource.h>) Issue 1 Various essential POSIX functions and constants Issue 1 inode access and modification times Issue 3 User accounting database functions Issue 4 Wide-Character Handling, see C string handling Issue 4 NA1 (95) Wide-Character Classification and Mapping Utilities, see C character classification Issue 5 NA1 (95) Word-expansion like the shell would perform Issue 4

See also POSIX C standard library C++ standard library Windows API Windows.h

References Official List of headers in the POSIX library on opengroup.org

Description of the posix library from the Flux OSKit

Further reading