| Header file | Description | First released | C Standard |
|---|
<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 | Issue 1 | ANSI (89) |
<complex.h> | Complex Arithmetic, see C mathematical functions | Issue 6 | C99 |
<cpio.h> | Magic numbers for the cpio archive format | Issue 3 | |
<ctype.h> |
Character types |
Issue 1 |
ANSI (89) |
<dirent.h> | Allows the opening and listing of directories | Issue 2 | |
<dlfcn.h> | Dynamic linking | Issue 5 | |
<errno.h> | Retrieving Error Number | Issue 1 | ANSI (89) |
<fcntl.h> | File opening, locking and other operations | Issue 1 | |
<fenv.h> | Floating-Point Environment (FPE), see C mathematical functions | Issue 6 | C99 |
<float.h> | Floating-point types, see C data types | Issue 4 | ANSI (89) |
<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 sized integer types, see C data types | Issue 5 | C99 |
<iso646.h> | Alternative spellings, see C alternative tokens | Issue 5 | NA1 (95) |
<langinfo.h> | Language information constants – builds on C localization functions | Issue 2 | |
<libgen.h> | Pathname manipulation | Issue 4 | |
<limits.h> | Implementation-defined constants, see C data types | Issue 1 | ANSI (89) |
<locale.h> | Category macros, see C localization functions | Issue 3 | ANSI (89) |
<math.h> | Mathematical declarations, see C mathematical functions | Issue 1 | ANSI (89) |
<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 | Issue 1 | ANSI (89) |
<signal.h> | Signals, see C signal handling | Issue 1 | ANSI (89) |
<spawn.h> | Process spawning | Issue 6 | |
<stdarg.h> | Handle Variable Argument List | Issue 4 | ANSI (89) |
<stdbool.h> | Boolean type and values, see C data types | Issue 6 | C99 |
<stddef.h> | Standard type definitions, see C data types | Issue 4 | ANSI (89) |
<stdint.h> | Integer types, see C data types | Issue 6 | C99 |
<stdio.h> | Standard buffered input/output, see C file input/output | Issue 1 | ANSI (89) |
<stdlib.h> | Standard library definitions, see C standard library | Issue 3 | ANSI (89) |
<string.h> | Several String Operations, see C string handling | Issue 1 | ANSI (89) |
<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 Berkeley 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 | Issue 6 | C99 |
<time.h> | Type-Generic Macros, see C date and time functions | Issue 1 | ANSI (89) |
<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 | Issue 4 | NA1 (95) |
<wctype.h> | Wide-Character Classification and Mapping Utilities, see C character classification | Issue 5 | NA1 (95) |
<wordexp.h> | Word-expansion like the shell would perform | Issue 4 | |