unistd(5) unistd(5)
NAME [Toc] [Back]
unistd: unistd.h - standard structures and symbolic constants
SYNOPSIS [Toc] [Back]
#include <unistd.h>
DESCRIPTION [Toc] [Back]
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 [Toc] [Back]
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
Std1003.1 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
Std1003.2 standard implemented. The
current value is 199209L, indicating the
(4-digit) year and (2-digit) month that
the standard was approved by the IEEE
Standards Board.
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unistd(5) unistd(5)
_POSIX2_C_VERSION Integer value indicating version of IEEE
Std1003.2 C-Language Binding Option
implemented. The current value is
199209L, 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_REALTIME_SIGNALS Implementation supports Realtime Signals
Extensions (true of all HP-UX
implementations).
_POSIX_SAVED_IDS Effective user and group are saved
across an exec() call (true of all HP-UX
implementations).
_POSIX_FSYNC Implementation supports File
Synchronization (true of all HP-UX
implementations). See open(2).
_POSIX_SYNCHRONIZED_IO Implementation supports Synchronized IO
(true of all HP-UX implementations).
See open(2).
_POSIX_VDISABLE Terminal special characters can be
disabled using this character (see
termio(7)).
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unistd(5) unistd(5)
_POSIX_THREADS Implementation supports POSIX threads.
_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 Std1003.2a
(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() alarm() brk() chdir()
chown() chroot() close() confstr()
crypt() ctermid() cuserid() dup()
dup2() encrypt() endusershell() execl()
execle() execlp() execv() execve()
execvp() _exit() fchown() fork()
fpathconf() fsync() ftruncate() getcwd()
getegid() geteuid() getgid() getgroups()
gethostname() getlogin() getopt()
getpass() getpgrp() getpgrp2() getpid()
getppid() getuid() getusershell() initgroups()
ioctl() isatty() link() lockf()
logname() lseek() mkstemp() mktemp()
nice() pathconf() pause() pipe()
prealloc() read() readlink() rmdir()
sbrk() setgid() setgroups() sethostname()
setpgid() setpgrp() setpgrp2() setresgid()
setresuid() setsid() setuid() setusershell()
sgetl() sleep() sputl() swab()
swapon() symlink() sync() sysconf()
tcgetpgrp() tcsetpgrp() truncate() ttyname()
ttyslot() unlink() vfork() write()
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unistd(5) unistd(5)
AUTHOR [Toc] [Back]
unistd was developed by HP.
SEE ALSO [Toc] [Back]
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).
STANDARDS CONFORMANCE [Toc] [Back]
<unistd.h>: AES, SVID3, XPG2, XPG3, XPG4, FIPS 151-2, POSIX.1,
POSIX.2, POSIX.4
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