Note this table does not include the header files defined by the ISO C standard.
| Header File |
Description |
First Released |
| <aio.h> |
Asynchronous input and output |
Issue 5 |
| <arpa/inet.h> |
Functions for manipulating numeric IP addresses (part of Berkeley sockets) |
Issue 6 |
| <assert.h> |
Verify Assumptions |
?? |
| <complex.h> |
Complex Arithmetic, see C mathematical functions |
?? |
| <cpio.h> |
Magic numbers for the cpio archive format. |
Issue 3 |
| <dirent.h> |
Allows the opening and listing of directories. |
Issue 2 |
| <dlfcn.h> |
Dynamic linking |
Issue 5 |
| <errno.h> |
Retrieving Error Number |
?? |
| <fcntl.h> |
File opening, locking and other operations. |
Issue 1 |
| <fenv.h> |
Floating-Point Environment, see C mathematical functions |
?? |
| <float.h> |
Floating Types, see C data types |
?? |
| <fmtmsg.h> |
Message display structures |
Issue 4 |
| <fnmatch.h> |
Filename matching |
Issue 4 |
| <ftw.h> |
File tree traversal |
Issue 1 |
| <glob.h> |
Pathname "globbing" (pattern-matching) |
Issue 4 |
| <grp.h> |
User group information and control. |
Issue 1 |
| <iconv.h> |
Codeset conversion facility |
Issue 4 |
| <inttypes.h> |
Fixed Size Integer Types, see C data types |
?? |
| <iso646.h> |
Alternative Spellings, see C alternative tokens |
?? |
| <langinfo.h> |
Language information constants. Build on C localization functions |
Issue 2 |
| <libgen.h> |
Pathname manipulation |
Issue 4 |
| <limits.h> |
Implementation-Defined Constants, see C data types |
?? |
| <locale.h> |
Category Macros, see C localization functions |
?? |
| <math.h> |
Mathematical Declarations, see C mathematical functions |
?? |
| <monetary.h> |
String formatting of monetary units |
Issue 4 |
| <mqueue.h> |
Message queue |
Issue 5 |
| <ndbm.h> |
NDBM database operations |
Issue 4 |
| <net/if.h> |
Listing of local network interfaces |
Issue 6 |
| <netdb.h> |
Translating protocol and host names into numeric addresses. Part of Berkeley sockets |
Issue 6 |
| <netinet/in.h> |
Defines Internet protocol and address family. Part of Berkeley sockets |
Issue 6 |
| <netinet/tcp.h> |
Additional TCP control options. Part of Berkeley sockets |
Issue 6 |
| <nl_types.h> |
Localization message catalog functions |
Issue 2 |
| <poll.h> |
Asynchronous file descriptor multiplexing |
Issue 4 |
| <pthread.h> |
Defines an API for creating and manipulating POSIX threads. |
Issue 5 |
| <pwd.h> |
passwd (user information) access and control. |
Issue 1 |
| <regex.h> |
Regular expression matching |
Issue 4 |
| <sched.h> |
Execution scheduling |
Issue 5 |
| <search.h> |
Search tables |
Issue 1 |
| <semaphore.h> |
POSIX semaphores |
Issue 5 |
| <setjmp.h> |
Stack Environment Declarations |
?? |
| <signal.h> |
Signals, see C signal handling |
?? |
| <spawn.h> |
Process spawning |
Issue 6 |
| <stdarg.h> |
Handle Variable Argument List |
?? |
| <stdbool.h> |
Boolean Type and Values, see C data types |
?? |
| <stddef.h> |
Standard Type Definitions, see C data types |
?? |
| <stdint.h> |
Integer Types, see C data types |
?? |
| <stdio.h> |
Standard Buffered Input/Oupt, see C file input/output |
?? |
| <stdlib.h> |
Standard Library Definitions, see C standard library |
?? |
| <string.h> |
Several String Operations, see C string handling |
?? |
| <strings.h> |
Case-insensitive string comparisons |
Issue 4 |
| <stropts.h> |
Stream manipulation, including ioctl |
Issue 4 |
| <sys/ipc.h> |
Inter-process communication (IPC). |
Issue 2 |
| <sys/mman.h> |
Memory management, including POSIX Shared Memory and Memory mapped files |
Issue 4 |
| <sys/msg.h> |
POSIX message queues. |
Issue 2 |
| <sys/resource.h> |
Resource usage, priorities, and limiting |
Issue 4 |
| <sys/select.h> |
Synchronous I/O multiplexing |
Issue 6 |
| <sys/sem.h> |
XSI (SysV style) semaphores |
Issue 2 |
| <sys/shm.h> |
XSI (SysV style) Shared Memory |
Issue 2 |
| <sys/socket.h> |
Main Berkley sockets header |
Issue 6 |
| <sys/stat.h> |
File information (stat et al.). |
Issue 1 |
| <sys/statvfs.h> |
File System information |
Issue 4 |
| <sys/time.h> |
Time and date functions and structures. |
Issue 4 |
| <sys/times.h> |
File access and modification times |
Issue 1 |
| <sys/types.h> |
Various data types used elsewhere. |
Issue 1 |
| <sys/uio.h> |
Vectored I/O operations |
Issue 4 |
| <sys/un.h> |
Unix domain sockets |
Issue 6 |
| <sys/utsname.h> |
Operating system information, including uname |
Issue 1 |
| <sys/wait.h> |
Status of terminated child processes (see wait) |
Issue 3 |
| <syslog.h> |
System error logging |
Issue 4 |
| <tar.h> |
Magic numbers for the tar archive format. |
Issue 3 |
| <termios.h> |
Allows terminal I/O interfaces. |
Issue 3 |
| <tgmath.h> |
Type-Generic Macros, see C mathematical functions |
?? |
| <time.h> |
Type-Generic Macros, see C date and time functions |
?? |
| <trace.h> |
Tracing of runtime behavior (DEPRECATED) |
Issue 6 |
| <ulimit.h> |
Resource limiting (DEPRECATED in favor of <sys/resource.h>) |
Issue 1 |
| <unistd.h> |
Various essential POSIX functions and constants. |
Issue 1 |
| <utime.h> |
inode access and modification times. |
Issue 3 |
| <utmpx.h> |
user accounting database functions |
Issue 4 |
| <wchar.h> |
Wide-Character Handling, see C string handling |
?? |
| <wctype.h> |
Wide-Character Classification and Mapping Utilities, see C character classification |
?? |
| <wordexp.h> |
Word-expansion like the shell would perform |
Issue 4 |
