unistd(5)
NAME
unistd.h − standard structures and symbolic constants
SYNOPSIS
#include <unistd.h>
DESCRIPTION
The header <unistd.h> defines the following structures and symbolic constants:
Symbolic constants for the access() function:
R_OK Test for read permission
W_OK Test for write permission
X_OK Test for execute (search) permission
F_OK Test for existence of file
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 all have distinct values.
Symbolic constant representing a null pointer:
NULL
Symbolic constants for the lseek() and fcntl() functions (the following constants have distinct values):
SEEK_SET Set file offset to "offset"
SEEK_CUR Set file offset to current plus "offset"
SEEK_END Set file offset to EOF plus "offset"
Symbolic constants (with fixed values):
_POSIX_VERSION Integer value indicating version of IEEE Std 1003.1 standard implemented. The current value is 199009L, indicating the (4-digit) year and (2-digit) month that the standard was approved by the IEEE Standards Board. However, if any of the symbols _AES_SOURCE, _XPG3, or _POSIX1_1988 is defined before <unistd.h> is included, the value of this symbol will be 198808L.
_POSIX2_VERSION
Integer value indicating version of IEEE Std 1003.2 standard implemented. The current value is 199210L, indicating the (4-digit) year and (2-digit) month that the standard was approved by the IEEE Standards Board.
_POSIX2_C_VERSION
Integer value indicating version of IEEE Std 1003.2 C-Language Binding Option implemented. The current value is 199210L, indicating the (4-digit) year and (2-digit) month that the standard was approved by the IEEE Standards Board.
_XOPEN_VERSION Integer value indicating issue number of the X/Open Portability Guide implemented. The current value is 4, indicating Issue 4. However, if the symbol _XPG3 is defined before <unistd.h> is included, the value of this symbol will be 3.
The following symbolic constants are defined in this header if the state of the corresponding option or restriction does not vary after compilation. If a symbol is absent from this header, the value or presence of the corresponding option or restriction should be determined at execution time through sysconf() or pathconf():
_POSIX_CHOWN_RESTRICTED the use of chown() is restricted to processes that have appropriate privileges
_POSIX_JOB_CONTROL implementation supports job control (true of all HP-UX implementations)
_POSIX_NO_TRUNC pathname components longer than NAME_MAX generate an error
_POSIX_SAVED_IDS effective user and group are saved across an exec() call (true of all HP-UX implementations)
_POSIX_VDISABLE terminal special characters can be disabled using this character (see termio(7))
_POSIX2_C_BIND all POSIX.2 C-language functionality is provided in the default libraries used by the c89 C compiler (see cc(1)).
_POSIX2_LOCALEDEF new locales can be defined by using the localedef command (see localedef(1M)).
_POSIX2_UPE the system supports IEEE Std 1003.2a ( POSIX User Portability Utilities Option)
_POSIX2_CHAR_TERM at least one terminal exists that supports all required POSIX.2a commands.
All symbolic constants whose names begin _CS, _PC, and _SC (see confstr(3C), pathconf(2), and sysconf(2)) are defined.
The following symbolic constants for file streams are defined:
STDIN_FILENO File number of standard input (stdin).
STDOUT_FILENO File number of standard output (stdout).
STDERR_FILENO File number of standard error (stderr).
The types size_t, ssize_t, uid_t, gid_t, off_t, and pid_t are defined.
Declarations are provided for the following functions:
| access() | fork() | initgroups() | setpgrp() |
| alarm() | fpathconf() | ioctl() | setpgrp2() |
| brk() | fsync() | isatty() | setresgid() |
| chdir() | ftruncate() | link() | setresuid() |
| chown() | getcdf() | lockf() | setsid() |
| chroot() | getcontext() | logname() | setuid() |
| close() | getcwd() | lseek() | setusershell() |
| confstr() | getegid() | lsync() | sgetl() |
| crypt() | geteuid() | mkstemp() | sleep() |
| ctermid() | getgid() | mktemp() | sputl() |
| cuserid() | getgroups() | nice() | swab() |
| dup() | gethcwd() | pathconf() | swapon() |
| dup2() | gethostname() | pause() | symlink() |
| encrypt() | getlogin() | pipe() | sync() |
| endusershell() | getopt() | prealloc() | sysconf() |
| execl() | getpass() | read() | tcgetpgrp() |
| execle() | getpgrp() | readlink() | tcsetpgrp() |
| execlp() | getpgrp2() | rmdir() | truncate() |
| execv() | getpid() | sbrk() | ttyname() |
| execve() | getppid() | setgid() | ttyslot() |
| execvp() | getuid() | setgroups() | unlink() |
| _exit() | getusershell() | sethostname() | vfork() |
| fchown() | hidecdf() | setpgid() | write() |
SEE ALSO
access(2), chown(2), confstr(3C), exit(2), fcntl(2), kill(2), lseek(2), open(2), pathconf(2), sysconf(2), limits(5), stdsyms(5), termio(7).
AUTHOR
unistd was developed by HP.
STANDARDS CONFORMANCE
<unistd.h>: AES, XPG2, XPG3, XPG4, FIPS 151-2, POSIX.1, POSIX.2
Hewlett-Packard Company — HP-UX Release 9.0: August 1992