unistd.h.html

IEEE 1003.1-2003, Single Unix Specification v3

The implementation supports the Issue 4, Version 2 Enhanced Internationalization Option Group. This symbol shall always be set to a
value other than -1.</dd>

<dt>_XOPEN_LEGACY</dt>

<dd>
The implementation supports the Legacy Option Group.</dd>

<dt>_XOPEN_REALTIME</dt>

<dd>
The implementation supports the X/Open Realtime Option Group.</dd>

<dt>_XOPEN_REALTIME_THREADS</dt>

<dd>
The implementation supports the X/Open Realtime Threads Option Group.</dd>

<dt>_XOPEN_SHM</dt>

<dd>
The implementation supports the Issue 4, Version 2 Shared Memory Option Group. This symbol shall always be set to a value other
than -1.</dd>

<dt>_XOPEN_STREAMS</dt>

<dd>
The implementation supports the XSI STREAMS Option Group. <img src="../images/opt-end.gif" alt="[Option End]" border="0"></dd>

<dt>_XOPEN_UNIX</dt>

<dd><sup>[<a href="javascript:open_code('XSI')">XSI</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border=
"0"><br>
The implementation supports the XSI extension. <img src="../images/opt-end.gif" alt="[Option End]" border="0"></dd>
</dl>

<h5><a name="tag_13_80_03_03"></a>Execution-Time Symbolic Constants</h5>

<p>If any of the following constants are not defined in the <i>&lt;unistd.h&gt;</i> header, the value shall vary depending on the
file to which it is applied.</p>

<p>If any of the following constants are defined to have value -1 in the <i>&lt;unistd.h&gt;</i> header, the implementation shall
not provide the option on any file; if any are defined to have a value other than -1 in the <i>&lt;unistd.h&gt;</i> header, the
implementation shall provide the option on all applicable files.</p>

<p>All of the following constants, whether defined in <i>&lt;unistd.h&gt;</i> or not, may be queried with respect to a specific
file using the <a href="../functions/pathconf.html"><i>pathconf</i>()</a> or <a href=
"../functions/fpathconf.html"><i>fpathconf</i>()</a> functions:</p>

<dl compact>
<dt>_POSIX_ASYNC_IO</dt>

<dd>
Asynchronous input or output operations may be performed for the associated file.</dd>

<dt>_POSIX_PRIO_IO</dt>

<dd>
Prioritized input or output operations may be performed for the associated file.</dd>

<dt>_POSIX_SYNC_IO</dt>

<dd>
Synchronized input or output operations may be performed for the associated file.</dd>
</dl>

<h5><a name="tag_13_80_03_04"></a>Constants for Functions</h5>

<p>The following symbolic constant shall be defined:</p>

<dl compact>
<dt>NULL</dt>

<dd>Null pointer</dd>
</dl>

<p>The following symbolic constants shall be defined for the <a href="../functions/access.html"><i>access</i>()</a> function:</p>

<dl compact>
<dt>F_OK</dt>

<dd>Test for existence of file.</dd>

<dt>R_OK</dt>

<dd>Test for read permission.</dd>

<dt>W_OK</dt>

<dd>Test for write permission.</dd>

<dt>X_OK</dt>

<dd>Test for execute (search) permission.</dd>
</dl>

<p>The constants F_OK, R_OK, W_OK, and X_OK and the expressions <i>R_OK</i>|<i>W_OK</i>, <i>R_OK</i>|<i>X_OK</i>, and
<i>R_OK</i>|<i>W_OK</i>|<i>X_OK</i> shall all have distinct values.</p>

<p>The following symbolic constants shall be defined for the <a href="../functions/confstr.html"><i>confstr</i>()</a> function:</p>

<dl compact>
<dt>_CS_PATH</dt>

<dd>
This is the value for the <i>PATH</i> environment variable that finds all standard utilities.</dd>

<dt>_CS_POSIX_V6_ILP32_OFF32_CFLAGS</dt>

<dd>
If <i>sysconf</i>(_SC_V6_ILP32_OFF32) returns -1, the meaning of this value is unspecified. Otherwise, this value is the set of
initial options to be given to the <a href="../utilities/c99.html"><i>c99</i></a> utility to build an application using a
programming model with 32-bit <b>int</b>, <b>long</b>, <b>pointer</b>, and <b>off_t</b> types.</dd>

<dt>_CS_POSIX_V6_ILP32_OFF32_LDFLAGS</dt>

<dd>
If <i>sysconf</i>(_SC_V6_ILP32_OFF32) returns -1, the meaning of this value is unspecified. Otherwise, this value is the set of
final options to be given to the <a href="../utilities/c99.html"><i>c99</i></a> utility to build an application using a programming
model with 32-bit <b>int</b>, <b>long</b>, <b>pointer</b>, and <b>off_t</b> types.</dd>

<dt>_CS_POSIX_V6_ILP32_OFF32_LIBS</dt>

<dd>
If <i>sysconf</i>(_SC_V6_ILP32_OFF32) returns -1, the meaning of this value is unspecified. Otherwise, this value is the set of
libraries to be given to the <a href="../utilities/c99.html"><i>c99</i></a> utility to build an application using a programming
model with 32-bit <b>int</b>, <b>long</b>, <b>pointer</b>, and <b>off_t</b> types.</dd>

<dt>_CS_POSIX_V6_ILP32_OFFBIG_CFLAGS</dt>

<dd>
If <i>sysconf</i>(_SC_V6_ILP32_OFFBIG) returns -1, the meaning of this value is unspecified. Otherwise, this value is the set of
initial options to be given to the <a href="../utilities/c99.html"><i>c99</i></a> utility to build an application using a
programming model with 32-bit <b>int</b>, <b>long</b>, and <b>pointer</b> types, and an <b>off_t</b> type using at least 64
bits.</dd>

<dt>_CS_POSIX_V6_ILP32_OFFBIG_LDFLAGS</dt>

<dd>
If <i>sysconf</i>(_SC_V6_ILP32_OFFBIG) returns -1, the meaning of this value is unspecified. Otherwise, this value is the set of
final options to be given to the <a href="../utilities/c99.html"><i>c99</i></a> utility to build an application using a programming
model with 32-bit <b>int</b>, <b>long</b>, and <b>pointer</b> types, and an <b>off_t</b> type using at least 64 bits.</dd>

<dt>_CS_POSIX_V6_ILP32_OFFBIG_LIBS</dt>

<dd>
If <i>sysconf</i>(_SC_V6_ILP32_OFFBIG) returns -1, the meaning of this value is unspecified. Otherwise, this value is the set of
libraries to be given to the <a href="../utilities/c99.html"><i>c99</i></a> utility to build an application using a programming
model with 32-bit <b>int</b>, <b>long</b>, and <b>pointer</b> types, and an <b>off_t</b> type using at least 64 bits.</dd>

<dt>_CS_POSIX_V6_LP64_OFF64_CFLAGS</dt>

<dd>
If <i>sysconf</i>(_SC_V6_LP64_OFF64) returns -1, the meaning of this value is unspecified. Otherwise, this value is the set of
initial options to be given to the <a href="../utilities/c99.html"><i>c99</i></a> utility to build an application using a
programming model with 32-bit <b>int</b> and 64-bit <b>long</b>, <b>pointer</b>, and <b>off_t</b> types.</dd>

<dt>_CS_POSIX_V6_LP64_OFF64_LDFLAGS</dt>

<dd>
If <i>sysconf</i>(_SC_V6_LP64_OFF64) returns -1, the meaning of this value is unspecified. Otherwise, this value is the set of
final options to be given to the <a href="../utilities/c99.html"><i>c99</i></a> utility to build an application using a programming
model with 32-bit <b>int</b> and 64-bit <b>long</b>, <b>pointer</b>, and <b>off_t</b> types.</dd>

<dt>_CS_POSIX_V6_LP64_OFF64_LIBS</dt>

<dd>
If <i>sysconf</i>(_SC_V6_LP64_OFF64) returns -1, the meaning of this value is unspecified. Otherwise, this value is the set of
libraries to be given to the <a href="../utilities/c99.html"><i>c99</i></a> utility to build an application using a programming
model with 32-bit <b>int</b> and 64-bit <b>long</b>, <b>pointer</b>, and <b>off_t</b> types.</dd>

<dt>_CS_POSIX_V6_LPBIG_OFFBIG_CFLAGS</dt>

<dd>
If <i>sysconf</i>(_SC_V6_LPBIG_OFFBIG) returns -1, the meaning of this value is unspecified. Otherwise, this value is the set of
initial options to be given to the <a href="../utilities/c99.html"><i>c99</i></a> utility to build an application using a
programming model with an <b>int</b> type using at least 32 bits and <b>long</b>, <b>pointer</b>, and <b>off_t</b> types using at
least 64 bits.</dd>

<dt>_CS_POSIX_V6_LPBIG_OFFBIG_LDFLAGS</dt>

<dd>
If <i>sysconf</i>(_SC_V6_LPBIG_OFFBIG) returns -1, the meaning of this value is unspecified. Otherwise, this value is the set of
final options to be given to the <a href="../utilities/c99.html"><i>c99</i></a> utility to build an application using a programming
model with an <b>int</b> type using at least 32 bits and <b>long</b>, <b>pointer</b>, and <b>off_t</b> types using at least 64
bits.</dd>

<dt>_CS_POSIX_V6_LPBIG_OFFBIG_LIBS</dt>

<dd>
If <i>sysconf</i>(_SC_V6_LPBIG_OFFBIG) returns -1, the meaning of this value is unspecified. Otherwise, this value is the set of
libraries to be given to the <a href="../utilities/c99.html"><i>c99</i></a> utility to build an application using a programming
model with an <b>int</b> type using at least 32 bits and <b>long</b>, <b>pointer</b>, and <b>off_t</b> types using at least 64
bits.</dd>

<dt>_CS_POSIX_V6_WIDTH_RESTRICTED_ENVS</dt>

<dd>
This value is a &lt;newline&gt;-separated list of names of programming environments supported by the implementation in which the
widths of the <b>blksize_t</b>, <b>cc_t</b>, <b>mode_t</b>, <b>nfds_t</b>, <b>pid_t</b>, <b>ptrdiff_t</b>, <b>size_t</b>,
<b>speed_t</b>, <b>ssize_t</b>, <b>suseconds_t</b>, <b>tcflag_t</b>, <b>useconds_t</b>, <b>wchar_t</b>, and <b>wint_t</b> types are
no greater than the width of type <b>long</b>.</dd>
</dl>

<p><sup>[<a href="javascript:open_code('XSI')">XSI</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
The following symbolic constants are reserved for compatibility with Issue 5:</p>

<p><br>
_CS_XBS5_ILP32_OFF32_CFLAGS (<b>LEGACY</b>)<br>
 _CS_XBS5_ILP32_OFF32_LDFLAGS (<b>LEGACY</b>)<br>
 _CS_XBS5_ILP32_OFF32_LIBS (<b>LEGACY</b>)<br>
 _CS_XBS5_ILP32_OFF32_LINTFLAGS (<b>LEGACY</b>)<br>
 _CS_XBS5_ILP32_OFFBIG_CFLAGS (<b>LEGACY</b>)<br>
_CS_XBS5_ILP32_OFFBIG_LDFLAGS (<b>LEGACY</b>)<br>
 _CS_XBS5_ILP32_OFFBIG_LIBS (<b>LEGACY</b>)<br>
 _CS_XBS5_ILP32_OFFBIG_LINTFLAGS (<b>LEGACY</b>)<br>
 _CS_XBS5_LP64_OFF64_CFLAGS (<b>LEGACY</b>)<br>
 _CS_XBS5_LP64_OFF64_LDFLAGS (<b>LEGACY</b>)<br>
 _CS_XBS5_LP64_OFF64_LIBS (<b>LEGACY</b>)<br>
 _CS_XBS5_LP64_OFF64_LINTFLAGS (<b>LEGACY</b>)<br>
 _CS_XBS5_LPBIG_OFFBIG_CFLAGS (<b>LEGACY</b>)<br>
 _CS_XBS5_LPBIG_OFFBIG_LDFLAGS (<b>LEGACY</b>)<br>
 _CS_XBS5_LPBIG_OFFBIG_LIBS (<b>LEGACY</b>)<br>
 _CS_XBS5_LPBIG_OFFBIG_LINTFLAGS (<b>LEGACY</b>)<br>
 <img src="../images/opt-end.gif" alt="[Option End]" border="0"><br>
</p>

<p>The following symbolic constants shall be defined for the <a href="../functions/lseek.html"><i>lseek</i>()</a> and <a href=
"../functions/fcntl.html"><i>fcntl</i>()</a> functions and shall have distinct values:</p>

<dl compact>
<dt>SEEK_CUR</dt>

<dd>Set file offset to current plus <i>offset</i>.</dd>

<dt>SEEK_END</dt>

<dd>Set file offset to EOF plus <i>offset</i>.</dd>

<dt>SEEK_SET</dt>

<dd>Set file offset to <i>offset</i>.</dd>
</dl>

<p>The following symbolic constants shall be defined as possible values for the <i>function</i> argument to the <a href=
"../functions/lockf.html"><i>lockf</i>()</a> function:</p>

<dl compact>
<dt>F_LOCK</dt>

<dd>Lock a section for exclusive use.</dd>

<dt>F_TEST</dt>

<dd>Test section for locks by other processes.</dd>

<dt>F_TLOCK</dt>

<dd>Test and lock a section for exclusive use.</dd>

<dt>F_ULOCK</dt>

<dd>Unlock locked sections.</dd>
</dl>

<p>The following symbolic constants shall be defined for <a href="../functions/pathconf.html"><i>pathconf</i>()</a>:</p>

<p><br>
 _PC_ALLOC_SIZE_MIN<br>
_PC_ASYNC_IO<br>
_PC_CHOWN_RESTRICTED<br>
_PC_FILESIZEBITS<br>
_PC_LINK_MAX<br>
_PC_MAX_CANON<br>
_PC_MAX_INPUT<br>
_PC_NAME_MAX<br>
_PC_NO_TRUNC<br>
_PC_PATH_MAX<br>
_PC_PIPE_BUF<br>
_PC_PRIO_IO<br>
_PC_REC_INCR_XFER_SIZE<br>
_PC_REC_MIN_XFER_SIZE<br>
_PC_REC_XFER_ALIGN<br>
_PC_SYMLINK_MAX<br>
_PC_SYNC_IO<br>
_PC_VDISABLE<br>
</p>