INTRO(3) Introduction to Library Functions INTRO(3)
NAME
Intro, intro - introduction to functions and libraries
DESCRIPTION
This section describes functions found in various Solaris libraries,
other than those functions described in Section 2 of this manual that
directly invoke UNIX system primitives. Function declarations can be
obtained from the
#include files indicated on each page. Pages are
grouped by library and are identified by the library name (or an
abbreviation of the library name) after the section number.
Collections of related libraries are grouped into volumes as
described below. The first volume contains pages describing the
contents of each shared library and each header used by the
functions, macros, and external variables described in the remaining
volumes.
Library Interfaces and Headers
This volume describes the contents of each shared library and each
header used by functions, macros, and external variables described in
the remaining volumes.
(3LIB) The libraries described in this section are implemented as shared
objects.
Descriptions of shared objects can include a definition of the
global symbols that define the shared objects' public interface,
for example
SUNW_1.1. Other interfaces can exist within the
shared object, for example
SUNWprivate.1.1. The public interface
provides a stable, committed set of symbols for application
development. The private interfaces are for internal use only,
and could change at any time.
(3HEAD) The headers described in this section are used by functions,
macros, and external variables. Headers contain function
prototypes, definitions of symbolic constants, common structures,
preprocessor macros, and defined types. Each function described
in the remaining five volumes specifies the headers that an
application must include in order to use that function. In most
cases only one header is required. These headers are present on
an application development system; they do have to be present on
the target execution system.
Basic Library Functions
The functions described in this volume are the core C library
functions that are basic to application development.
(3C) These functions, together with those of Section 2, constitute the
standard C library,
libc, which is automatically linked by the C
compilation system. The standard C library is implemented as a
shared object,
libc.so. See
libc(3LIB) and the "C Compilation
System" chapter of the
ANSI C Programmer's Guide for a
discussion. Some functions behave differently in standard-
conforming environments. This behavior is noted on the individual
manual pages. See
standards(7).
The
libpthread and
libthread libraries are filter libraries on
libc that are used for building multithreaded applications:
libpthread implements the POSIX (see
standards(7)) threads
interface, whereas
libthread implements the Solaris threads
interface. See
MULTITHREADED APPLICATIONS, below.
(3C_DB) These functions constitute the threads debugging library,
libc_db. This library is implemented as a shared object,
libc_db.so, but is not automatically linked by the C compilation
system. Specify
-lc_db on the
cc command line to link with this
library. See
libc_db(3LIB).
(3MALLOC) These functions constitute the various memory allocation
libraries:
libmalloc,
libbsdmalloc,
libmapmalloc,
libmtmalloc,
and
libumem. Each of these libraries is implemented as a shared
object (
libmalloc.so,
libbsdmalloc.so,
libmapmalloc.so,
libmtmalloc.so, and
libumem.so). These libraries are not
automatically linked by the C compilation system. Specify
-lmalloc,
-lbsdmalloc,
-lmapmalloc,
-lmtmalloc, and
-lumem to
link with, respectively,
libmalloc,
libbsdmalloc,
libmapmalloc,
libmtmalloc, and
libumem. See
libmalloc(3LIB),
libbsdmalloc(3LIB),
libmapmalloc(3LIB),
libmtmalloc(3LIB), and
libumem(3LIB).
Networking Library Functions
The functions described in this volume comprise the various
networking libraries.
(3COMMPUTIL) These functions constitute the communication protocol parser
utilities library,
libcommputil. This library is implemented as a
shared object,
libcommputil.so, but it is not automatically
linked by the C compilation system. Specify
-lcommputil on the
cc command line to link with this library. See
libcommputil(3LIB).
(3DLPI) These functions constitute the data link provider interface
library,
libdlpi. This library is implemented as a shared object,
libdlpi.so, but it is not automatically linked by the C
compilation system. Specify
-ldlpi on the
cc command line to link
with this library. See
libdlpi(3LIB).
(3DNS_SD) These functions constitute the DNS service discovery library,
libdns_sd. This library is implemented as a shared object,
libdns_sd.so, but it is not automatically linked by the C
compilation system. Specify
-ldns_sd on the
cc command line to
link with this library. See
libdns_sd(3LIB).
(3GSS) These functions constitute the generic security services library.
This library is implemented as a shared object,
libgss.so, but it
is not automatically linked by the C compilation system. Specify
-lgss on the
cc command line to link with this library. See
libgss(3LIB).
(3LDAP) These functions constitute the lightweight directory access
protocol library,
libldap. This library is implemented as a
shared object,
libldap.so, but is not automatically linked by the
C compilation system. Specify
-lldap on the
cc command line to
link with this library. See
ldap(3LDAP).
(3NSL) These functions constitute the network service library,
libnsl.
This library is implemented as a shared object,
libnsl.so, but is
not automatically linked by the C compilation system. Specify
-lnsl on the
cc command line to link with this library. See
libnsl(3LIB).
Many base networking functions are also available in the X/Open
networking interfaces library,
libxnet. See section (3XNET) below
for more information on the
libxnet interfaces.
(3RESOLV) These functions constitute the resolver library,
libresolv. This
library is implemented as a shared object,
libresolv.so, but is
not automatically linked by the C compilation system. Specify
-lresolv on the
cc command line to link with this library. See
libresolv(3LIB).
(3RPC) These functions constitute the remote procedure call libraries,
librpcsvc and
librpcsoc. The latter is provided for compatibility
only; new applications should not link to it. Both libraries are
implemented as shared objects,
librpcsvc.so and
librpcsoc.so,
respectively. Neither library is automatically linked by the C
compilation system. Specify
-lrpcsvc or
-lrpcsoc on the
cc command line to link with these libraries. See
librpcsvc(3LIB).
(3SASL) These functions constitute the simple authentication and security
layer library,
libsasl. This library is implemented as a shared
object,
libsasl.so, but it is not automatically linked by the C
compilation system. Specify
-lsasl on the
cc command line to link
with this library. See
libsasl(3LIB).
(3SIP) These functions constitute the session initiation protocol
library,
libsip. This library is implemented as a shared object,
libsip.so, but it is not automatically linked by the C
compilation system. Specify
-lsip on the
cc command line to link
with this library. See
libsip(3LIB).
(3SLP) These functions constitute the service location protocol library,
libslp. This library is implemented as a shared object,
libslp.so, but it is not automatically linked by the C
compilation system. Specify
-lslp on the
cc command line to link
with this library. See
libslp(3LIB).
(3SOCKET) These functions constitute the sockets library,
libsocket. This
library is implemented as a shared object,
libsocket.so, but is
not automatically linked by the C compilation system. Specify
-lsocket on the
cc command line to link with this library. See
libsocket(3LIB).
(3XNET) These functions constitute X/Open networking interfaces which
comply with the X/Open CAE Specification, Networking Services,
Issue 4 (September, 1994). This library is implemented as a
shared object,
libxnet.so, but is not automatically linked by the
C compilation system. Specify
-lxnet on the
cc command line to
link with this library. See
libxnet(3LIB) and
standards(7) for
compilation information.
Under all circumstances, the use of the Sockets API is recommended
over the XTI and TLI APIs. If portability to other XPGV4v2 (see
standards(7)) systems is a requirement, the application must use the
libxnet interfaces. If portability is not required, the sockets
interfaces in
libsocket and
libnsl are recommended over those in
libxnet. Between the XTI and TLI APIs, the
XTI interfaces (available
with
libxnet) are recommended over the
TLI interfaces (available with
libnsl).
Curses Library Functions
The functions described in this volume comprise the libraries that
provide graphics and character screen updating capabilities.
(3CURSES) The functions constitute the following libraries:
libcurses These functions constitute the curses library,
libcurses.
This library is implemented as a shared object,
libcurses.so,
but is not automatically linked by the C compilation system.
Specify
-lcurses on the
cc command line to link with this
library. See
libcurses(3LIB).
libform These functions constitute the forms library,
libform. This
library is implemented as a shared object,
libform.so, but is
not automatically linked by the C compilation system. Specify
-lform on the
cc command line to link with this library. See
libform(3LIB).
libmenu These functions constitute the menus library,
libmenu. This
library is implemented as a shared object,
libmenu.so, but is
not automatically linked by the C compilation system. Specify
-lmenu on the
cc command line to link with this library. See
libmenu(3LIB).
libpanel These functions constitute the panels library,
libpanel. This
library is implemented as a shared object,
libpanel.so, but
is not automatically linked by the C compilation system.
Specify
-lpanel on the
cc command line to link with this
library. See
libpanel(3LIB).
(3XCURSES) These functions constitute the X/Open curses library, located in
/usr/xpg4/lib/libcurses.so. This library provides a set of
internationalized functions and macros for creating and modifying
input and output to a terminal screen. Included in this library
are functions for creating windows, highlighting text, writing to
the screen, reading from user input, and moving the cursor.
X/Open Curses is designed to optimize screen update activities.
The X/Open Curses library conforms fully with Issue 4 of the
X/Open Extended Curses specification. See
libcurses(3XCURSES).
Extended Library Functions
The functions described in this volume comprise the following
specialized libraries:
(3BSM) These functions constitute the auditing library,
libbsm. This
library is implemented as a shared object,
libbsm.so, but is not
automatically linked by the C compilation system. Specify
-lbsm on the
cc command line to link with this library. See
libbsm(3LIB).
(3CFGADM) These functions constitute the configuration administration
library,
libcfgadm. This library is implemented as a shared
object,
libcfgadm.so, but is not automatically linked by the C
compilation system. Specify
-lcfgadm on the
cc command line to
link with this library. See
libcfgadm(3LIB).
(3CONTRACT) These functions constitute the contract management library,
libcontract. This library is implemented as a shared object,
libcontract.so, but is not automatically linked by the C
compilation system. Specify
-lcontract on the
cc command line to
link with this library. See
libcontract(3LIB).
(3CPC) These functions constitute the CPU performance counter library,
libcpc, and the process context library,
libpctx. These libraries
are implemented as shared objects,
libcpc.so and
libpctx.so,
respectively, but are not automatically linked by the C
compilation system. Specify
-lcpc or
-lpctx on the
cc command
line to link with these libraries. See
libcpc(3LIB) and
libpctx(3LIB).
(3DAT) These functions constitute the direct access transport library,
libdat. This library is implemented as a shared object,
libdat.so, but is not automatically linked by the C compilation
system. Specify
-ldat on the
cc command line to link with this
library. See
libdat(3LIB).
(3DEVID) These functions constitute the device
ID library,
libdevid. This
library is implemented as a shared object,
libdevid.so, but is
not automatically linked by the C compilation system. Specify
-ldevid on the
cc command line to link with this library. See
libdevid(3LIB).
(3DEVINFO) These functions constitute the device information library,
libdevinfo. This library is implemented as a shared object,
libdevinfo.so, but is not automatically linked by the C
compilation system. Specify
-ldevinfo on the
cc command line to
link with this library. See
libdevinfo(3LIB).
(3ELF) These functions constitute the ELF access library,
libelf,
(Extensible Linking Format). This library provides the interface
for the creation and analyses of "elf" files; executables,
objects, and shared objects.
libelf is implemented as a shared
object,
libelf.so, but is not automatically linked by the C
compilation system. Specify
-lelf on the
cc command line to link
with this library. See
libelf(3LIB).
(3EXACCT) These functions constitute the extended accounting access
library,
libexacct, and the project database access library,
libproject. These libraries are implemented as shared objects,
libexacct.so and
libproject.so, respectively, but are not
automatically linked by the C compilation system. Specify
-lexacct or
-lproject on the
cc command line to link with these
libraries. See
libexacct(3LIB) and
libproject(3LIB).
(3FCOE) These functions constitute the Fibre Channel over Ethernet port
management library. This library is implemented as a shared
object,
libfcoe.so, but is not automatically linked by the C
compilation system. Specify
-lfcoe on the
cc command line to link
with this library. See
libfcoe(3LIB).
(3FSTYP) These functions constitute the file system type identification
library. This library is implemented as a shared object,
libfstyp.so, but is not automatically linked by the C compilation
system. Specify
-lfstyp on the
cc command line to link with this
library. See
libfstyp(3LIB).
(3GEN) These functions constitute the string pattern-matching and
pathname manipulation library,
libgen. This library is
implemented as a shared object,
libgen.so, but is not
automatically linked by the C compilation system. Specify
-lgen on the
cc command line to link with this library. See
libgen(3LIB).
(3HBAAPI) These functions constitute the common fibre channel HBA
information library,
libhbaapi. This library is implemented as a
shared object,
libhbaapi.so, but is not automatically linked by
the C compilation system. Specify
-lhbaapi on the
cc command line
to link with this library. See
libhbaapi(3LIB).
(3ISCSIT) These functions constitute the iSCSI Management library,
libiscsit. This library is implemented as a shared object,
libiscsit.so, but is not automatically linked by the C
compilation system. Specify
-liscsit on the
cc command line to
link with this library. See
libiscsit(3LIB).
(3KSTAT) These functions constitute the kernel statistics library, which
is implemented as a shared object,
libkstat.so, but is not
automatically linked by the C compilation system. Specify
-lkstat on the
cc command line to link with this library. See
libkstat(3LIB).
(3KVM) These functions allow access to the kernel's virtual memory
library, which is implemented as a shared object,
libkvm.so, but
is not automatically linked by the C compilation system. Specify
-lkvm on the
cc command line to link with this library. See
libkvm(3LIB).
(3LGRP) These functions constitute the locality group library, which is
implemented as a shared object,
liblgrp.so, but is not
automatically linked by the C compilation system. Specify
-llgrp on the
cc command line to link with this library. See
liblgrp(3LIB).
(3M) These functions constitute the mathematical library,
libm. This
library is implemented as a shared object,
libm.so, but is not
automatically linked by the C compilation system. Specify
-lm on
the
cc command line to link with this library. See
libm(3LIB).
(3MAIL) These functions constitute the user mailbox management library,
libmail. This library is implemented as a shared object,
libmail.so, but is not automatically linked by the C compilation
system. Specify
-lmail on the
cc command line to link with this
library. See
libmail(3LIB).
(3MP) These functions constitute the integer mathematical library,
libmp. This library is implemented as a shared object,
libmp.so,
but is not automatically linked by the C compilation system.
Specify
-lmp on the
cc command line to link with this library.
See
libmp(3LIB).
(3MPAPI) These functions constitute the Common Multipath Management
library,
libMPAPI. This library is implemented as a shared
object,
libMPAPI.so, but is not automatically linked by the C
compilation system. Specify
-lMPAPI on the
cc command line to
link with this library. See
libMPAPI(3LIB).
(3MVEC) These functions constitute the vector mathematical library,
libmvec. This library is implemented as a shared object,
libmvec.so, but is not automatically linked by the C compilation
system. Specify
-lmvec on the
cc command line to link with this
library. See
libmvec(3LIB).
(3NVPAIR) These functions constitute the name-value pair library,
libnvpair. This library is implemented as a shared object,
libnvpair.so, but is not automatically linked by the C
compilation system. Specify
-lnvpair on the
cc command line to
link with this library. See
libnvpair(3LIB).
(3PAM) These functions constitute the pluggable authentication module
library,
libpam. This library is implemented as a shared object,
libpam.so, but is not automatically linked by the C compilation
system. Specify
-lpam on the
cc command line to link with this
library. See
libpam(3LIB).
(3PAPI) These functions constitute the Free Standards Group Open Printing
API (PAPI) library,
libpapi. This library is implemented as a
shared object,
libpapi.so, but is not automatically linked by the
C compilation system. Specify
-lpapi on the
cc command line to
link with this library. See
libpapi(3LIB).
(3PICL) These functions constitute the PICL library,
libpicl. This
library is implemented as a shared object,
libpicl.so, but is not
automatically linked by the C compilation system. Specify
-lpicl on the
cc command line to link with this library. See
libpicl(3LIB) and
libpicl(3PICL).
(3PICLTREE) These functions constitute the PICL plug-in library,
libpicltree.
This library is implemented as a shared object,
libpicltree.so,
but is not automatically linked by the C compilation system.
Specify
-lpicltree on the
cc command line to link with this
library. See
libpicltree(3LIB) and
libpicltree(3PICLTREE).
(3POOL) These functions constitute the pool configuration manipulation
library,
libpool. This library is implemented as a shared object,
libpool.so, but is not automatically linked by the C compilation
system. Specify
-lpool on the
cc command line to link with this
library. See
libpool(3LIB).
(3PROC) These functions constitute the process manipulation library,
libproc. This library is implemented as a shared object,
libproc.so, but it is not automatically linked by the C
compilation system. Specify
-lproc on the
cc command line to link
with this library. See
libproc(3LIB).
(3PROJECT) These functions constitute the project database access library,
libproject. This library is implemented as a shared object,
libproject.so, but is not automatically linked by the C
compilation system. Specify
-lproject on the
cc command line to
link with this library. See
libproject(3LIB).
(3RSM) These functions constitute the remote shared memory library,
librsm. This library is implemented as a shared object,
librsm.so, but is not automatically linked by the C compilation
system. Specify
-lrsm on the
cc command line to link with this
library. See
librsm(3LIB).
(3SCF) These functions constitute the service configuration facility
library,
libscf. This library is implemented as a shared object,
libscf.so, but is not automatically linked by the C compilation
system. Specify
-lscf on the
cc command line to link with this
library. See
libscf(3LIB).
(3SEC) These functions constitute the file access control library,
libsec. This library is implemented as a shared object,
libsec.so, but is not automatically linked by the C compilation
system. Specify
-lsec on the
cc command line to link with this
library. See
libsec(3LIB).
(3SECDB) These functions constitute the security attributes database
library,
libsecdb. This library is implemented as a shared
object,
libsecdb.so, but is not automatically linked by the C
compilation system. Specify
-lsecdb on the
cc command line to
link with this library. See
libsecdb(3LIB).
(3STMF) These functions constitute the SCSI Target Mode Framework
library,
libstmf. This library is implemented as a shared object,
libstmf.so, but is not automatically linked by the C compilation
system. Specify
-lstmf on the
cc command line to link with this
library. See
libstmf(3LIB).
(3SYSEVENT) These functions constitute the system event library,
libsysevent.
This library is implemented as a shared object,
libsysevent.so,
but is not automatically linked by the C compilation system.
Specify
-lsysevent on the
cc command line to link with this
library. See
libsysevent(3LIB).
(3TECLA) These functions constitute the interactive command-line input
library,
libtecla. This library is implemented as a shared
object,
libtecla.so, but is not automatically linked by the C
compilation system. Specify
-ltecla on the
cc command line to
link with this library. See
libtecla(3LIB).
(3TSOL) These functions constitute the Trusted Extensions library,
libtsol, and the Trusted Extensions network library,
libtsnet.
These libraries are implemented as shared objects,
libtsol.so and
libtsnet.so, but are not automatically linked by the C
compilation system. Specify
-ltsol or
-ltsnet on the
cc command
line to link with these libraries. See
libtsol(3LIB) and
libtsnet(3LIB).
(3UUID) These functions constitute the universally unique identifier
library,
libuuid. This library is implemented as a shared object,
libuuid.so, but is not automatically linked by the C compilation
system. Specify
-luuid on the
cc command line to link with this
library. See
libuuid(3LIB).
(3VOLMGT) These functions constitute the volume management library,
libvolmgt. This library is implemented as a shared object,
libvolmgt.so, but is not automatically linked by the C
compilation system. Specify
-lvolmgt on the
cc command line to
link with this library. See
libvolmgt(3LIB).
DEFINITIONS
A character is any bit pattern able to fit into a byte on the
machine. In some international languages, however, a "character"
might require more than one byte, and is represented in multi-bytes.
The null character is a character with value 0, conventionally
represented in the C language as
\0. A character array is a sequence
of characters. A null-terminated character array (a
string) is a
sequence of characters, the last of which is the null character. The
null string is a character array containing only the terminating null
character. A null pointer is the value that is obtained by casting
0 into a pointer. C guarantees that this value will not match that of
any legitimate pointer, so many functions that return pointers return
NULL to indicate an error. The macro
NULL is defined in <
stdio.h>.
Types of the form
size_t are defined in the appropriate headers.
MULTITHREADED APPLICATIONS
Both POSIX threads and Solaris threads can be used within the same
application. Their implementations are completely compatible with
each other; however, only POSIX threads guarantee portability to
other POSIX-conforming environments.
The
libpthread(3LIB) and
libthread(3LIB) libraries are implemented as
filters on
libc(3LIB).
When compiling a multithreaded application, the
-mt option must be
specified on the command line.
There is no need for a multithreaded application to link with
-lthread. An application must link with
-lpthread only when POSIX
semantics for
fork(2) are desired. When an application is linked with
-lpthread, a call to
fork() assumes the behavior
fork1(2) rather than
the default behavior that forks all threads.
When compiling a POSIX-conforming application, either the
_POSIX_C_SOURCE or
_POSIX_PTHREAD_SEMANTICS option must be specified
on the command line. For POSIX.1c-conforming applications, define
the
_POSIX_C_SOURCE flag to be >= 199506L:
cc -mt [
flag... ]
file...
-D_POSIX_C_SOURCE=199506L -lpthread For POSIX behavior with the Solaris
fork() and
fork1() distinction,
compile as follows:
cc -mt [
flag... ]
file...
-D_POSIX_PTHREAD_SEMANTICS For Solaris threads behavior, compile as follows:
cc -mt [
flag... ]
file...
Unsafe interfaces should be called only from the main thread to
ensure the application's safety.
MT-Safe interfaces are denoted in the
ATTRIBUTES section of the
functions and libraries manual pages (see
attributes(7)). If a manual
page does not state explicitly that an interface is MT-Safe, the user
should assume that the interface is unsafe.
REALTIME APPLICATIONS
The environment variable
LD_BIND_NOW must be set to a non-null value
to enable early binding. Refer to the "When Relocations are
Processed" chapter in
Linker and Libraries Guide for additional
information.
FILES
INCDIR usually
/usr/include LIBDIR usually either
/lib or
/usr/lib (32-bit) or either
/lib/64 or
/usr/lib/64 (64-bit)
LIBDIR/*.so shared libraries
ACKNOWLEDGMENTS
Sun Microsystems, Inc. gratefully acknowledges The Open Group for
permission to reproduce portions of its copyrighted documentation.
Original documentation from The Open Group can be obtained online at
http://www.opengroup.org/bookstore/.
The Institute of Electrical and Electronics Engineers and The Open
Group, have given us permission to reprint portions of their
documentation.
In the following statement, the phrase ``this text'' refers to
portions of the system documentation.
Portions of this text are reprinted and reproduced in electronic form
in the SunOS Reference Manual, from IEEE Std 1003.1, 2004 Edition,
Standard for Information Technology -- Portable Operating System
Interface (POSIX), The Open Group Base Specifications Issue 6,
Copyright (C) 2001-2004 by the Institute of Electrical and
Electronics Engineers, Inc and The Open Group. In the event of any
discrepancy between these versions and the original IEEE and The Open
Group Standard, the original IEEE and The Open Group Standard is the
referee document. The original Standard can be obtained online at
http://www.opengroup.org/unix/online.html.
This notice shall appear on any product containing this material.
SEE ALSO
ar(1),
ld(1),
fork(2),
stdio(3C),
attributes(7),
standards(7) Linker and Libraries Guide Performance Profiling Tools ANSI C Programmer's GuideDIAGNOSTICS
For functions that return floating-point values, error handling
varies according to compilation mode. Under the
-Xt (default) option
to
cc, these functions return the conventional values
0,
+-HUGE, or
NaN when the function is undefined for the given arguments or when
the value is not representable. In the
-Xa and
-Xc compilation modes,
+-HUGE_VAL is returned instead of
+-HUGE. (
HUGE_VAL and
HUGE are
defined in
math.h to be infinity and the largest-magnitude single-
precision number, respectively.)
NOTES
None of the functions, external variables, or macros should be
redefined in the user's programs. Any other name can be redefined
without affecting the behavior of other library functions, but such
redefinition might conflict with a declaration in an included header.
The headers in
INCDIR provide function prototypes (function
declarations including the types of arguments) for most of the
functions listed in this manual. Function prototypes allow the
compiler to check for correct usage of these functions in the user's
program. The
lint program checker can also be used and will report
discrepancies even if the headers are not included with
#include statements. Definitions for Sections 2 and 3C are checked
automatically. Other definitions can be included by using the
-l option to
lint. (For example,
-lm includes definitions for
libm.)
Use of
lint is highly recommended. See the
lint chapter in
Performance Profiling Tools Users should carefully note the difference between STREAMS and
stream. STREAMS is a set of kernel mechanisms that support the
development of network services and data communication drivers. It is
composed of utility routines, kernel facilities, and a set of data
structures. A
stream is a file with its associated buffering. It is
declared to be a pointer to a type
FILE defined in
<stdio.h>.
In detailed definitions of components, it is sometimes necessary to
refer to symbolic names that are implementation-specific, but which
are not necessarily expected to be accessible to an application
program. Many of these symbolic names describe boundary conditions
and system limits.
In this section, for readability, these implementation-specific
values are given symbolic names. These names always appear enclosed
in curly brackets to distinguish them from symbolic names of other
implementation-specific constants that are accessible to application
programs by headers. These names are not necessarily accessible to an
application program through a header, although they can be defined in
the documentation for a particular system.
In general, a portable application program should not refer to these
symbolic names in its code. For example, an application program would
not be expected to test the length of an argument list given to a
routine to determine if it was greater than {
ARG_MAX}.
September 12, 2021 INTRO(3)
