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            <h1>POSIX</h1>


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<ul><li><a href="#NAME">NAME</a><li><a href="#SYNOPSIS">SYNOPSIS</a><li><a href="#DESCRIPTION">DESCRIPTION</a><li><a href="#CAVEATS">CAVEATS</a><li><a href="#FUNCTIONS">FUNCTIONS</a><li><a href="#CLASSES">CLASSES</a><ul><li><a href="#POSIX%3a%3aSigAction">POSIX::SigAction</a><li><a href="#POSIX%3a%3aSigRt">POSIX::SigRt</a><li><a href="#POSIX%3a%3aSigSet">POSIX::SigSet</a><li><a href="#POSIX%3a%3aTermios">POSIX::Termios</a></ul><li><a href="#PATHNAME-CONSTANTS">PATHNAME CONSTANTS</a><li><a href="#POSIX-CONSTANTS">POSIX CONSTANTS</a><li><a href="#SYSTEM-CONFIGURATION">SYSTEM CONFIGURATION</a><li><a href="#ERRNO">ERRNO</a><li><a href="#FCNTL">FCNTL</a><li><a href="#FLOAT">FLOAT</a><li><a href="#FLOATING-POINT-ENVIRONMENT">FLOATING-POINT ENVIRONMENT</a><li><a href="#LIMITS">LIMITS</a><li><a href="#LOCALE">LOCALE</a><li><a href="#MATH">MATH</a><li><a href="#SIGNAL">SIGNAL</a><li><a href="#STAT">STAT</a><li><a href="#STDLIB">STDLIB</a><li><a href="#STDIO">STDIO</a><li><a href="#TIME">TIME</a><li><a href="#UNISTD">UNISTD</a><li><a href="#WAIT">WAIT</a><li><a href="#WINSOCK">WINSOCK</a></ul><a name="NAME"></a><h1>NAME</h1>
<p>POSIX - Perl interface to IEEE Std 1003.1</p>
<a name="SYNOPSIS"></a><h1>SYNOPSIS</h1>
<pre class="verbatim"><ol><li>    <a class="l_k" href="functions/use.html">use</a> <span class="w">POSIX</span> <span class="s">(</span><span class="s">)</span><span class="sc">;</span></li><li>    <a class="l_k" href="functions/use.html">use</a> <span class="w">POSIX</span> <span class="q">qw(setsid)</span><span class="sc">;</span></li><li>    <a class="l_k" href="functions/use.html">use</a> <span class="w">POSIX</span> <span class="q">qw(:errno_h :fcntl_h)</span><span class="sc">;</span></li><li></li><li>    <a class="l_k" href="functions/printf.html">printf</a> <span class="q">&quot;EINTR is %d\n&quot;</span><span class="cm">,</span> <span class="w">EINTR</span><span class="sc">;</span></li><li></li><li>    <span class="i">$sess_id</span> = <span class="i">POSIX::setsid</span><span class="s">(</span><span class="s">)</span><span class="sc">;</span></li><li></li><li>    <span class="i">$fd</span> = <span class="i">POSIX::open</span><span class="s">(</span><span class="i">$path</span><span class="cm">,</span> <span class="w">O_CREAT</span>|<span class="w">O_EXCL</span>|<span class="w">O_WRONLY</span><span class="cm">,</span> <span class="n">0644</span><span class="s">)</span><span class="sc">;</span></li><li>	<span class="c"># note: that&#39;s a filedescriptor, *NOT* a filehandle</span></li></ol></pre><a name="DESCRIPTION"></a><h1>DESCRIPTION</h1>
<p>The POSIX module permits you to access all (or nearly all) the standard
POSIX 1003.1 identifiers.  Many of these identifiers have been given Perl-ish
interfaces.</p>
<p>This document gives a condensed list of the features available in the POSIX
module.  Consult your operating system's manpages for general information on
most features.  Consult <a href="perlfunc.html">perlfunc</a> for functions which are noted as being
identical to Perl's builtin functions.</p>
<p>The first section describes POSIX functions from the 1003.1 specification.
The second section describes some classes for signal objects, TTY objects,
and other miscellaneous objects.  The remaining sections list various
constants and macros in an organization which roughly follows IEEE Std
1003.1b-1993.</p>
<a name="CAVEATS"></a><h1>CAVEATS</h1>
<p><i>Everything is exported by default</i> (with a handful of exceptions).
This is an unfortunate backwards compatibility feature and its use is
<b>strongly <a href="perlpolicy.html#discouraged">discouraged</a></b>.
You should either prevent the exporting (by saying <code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">POSIX</span> <span class="s">(</span><span class="s">)</span><span class="sc">;</span></code>
,
as usual) and then use fully qualified names (e.g. <code class="inline"><span class="w">POSIX::SEEK_END</span></code>
),
or give an explicit import list.
If you do neither and opt for the default (as in <code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">POSIX</span><span class="sc">;</span></code>
), you
will import <i>hundreds and hundreds</i> of symbols into your namespace.</p>
<p>A few functions are not implemented because they are C specific.  If you
attempt to call these, they will print a message telling you that they
aren't implemented, and suggest using the Perl equivalent, should one
exist.  For example, trying to access the <code class="inline"><span class="i">setjmp</span><span class="s">(</span><span class="s">)</span></code>
 call will elicit the
message "<code class="inline"><span class="i">setjmp</span><span class="s">(</span><span class="s">)</span> <span class="w">is</span> <span class="w">C</span>-<span class="w">specific</span><span class="co">:</span> <a class="l_k" href="functions/use.html">use</a> <a class="l_k" href="functions/eval.html">eval</a> <span class="s">{</span><span class="s">}</span> <span class="w">instead</span></code>
".</p>
<p>Furthermore, some evil vendors will claim 1003.1 compliance, but in fact
are not so: they will not pass the PCTS (POSIX Compliance Test Suites).
For example, one vendor may not define <code class="inline"><span class="w">EDEADLK</span></code>
, or the semantics of the
errno values set by <code class="inline"><a class="l_k" href="functions/open.html">open(2)</a></code> might not be quite right.  Perl does not
attempt to verify POSIX compliance.  That means you can currently
successfully say "use POSIX",  and then later in your program you find
that your vendor has been lax and there's no usable <code class="inline"><span class="w">ICANON</span></code>
 macro after
all.  This could be construed to be a bug.</p>
<a name="FUNCTIONS"></a><h1>FUNCTIONS</h1>
<ul>
<li><a name="_exit"></a><b><code class="inline"><span class="w">_exit</span></code>
</b>
<p>This is identical to the C function <code class="inline"><span class="i">_exit</span><span class="s">(</span><span class="s">)</span></code>
.  It exits the program
immediately which means among other things buffered I/O is <b>not</b> flushed.</p>
<p>Note that when using threads and in Linux this is <b>not</b> a good way to
exit a thread because in Linux processes and threads are kind of the
same thing (Note: while this is the situation in early 2003 there are
projects under way to have threads with more POSIXly semantics in Linux).
If you want not to return from a thread, detach the thread.</p>
</li>
<li><a name="abort"></a><b><code class="inline"><span class="w">abort</span></code>
</b>
<p>This is identical to the C function <code class="inline"><span class="i">abort</span><span class="s">(</span><span class="s">)</span></code>
.  It terminates the
process with a <code class="inline"><span class="w">SIGABRT</span></code>
 signal unless caught by a signal handler or
if the handler does not return normally (it e.g.  does a <code class="inline"><span class="w">longjmp</span></code>
).</p>
</li>
<li><a name="abs"></a><b><code class="inline"><a class="l_k" href="functions/abs.html">abs</a></code></b>
<p>This is identical to Perl's builtin <code class="inline"><a class="l_k" href="functions/abs.html">abs()</a></code> function, returning
the absolute value of its numerical argument.</p>
</li>
<li><a name="access"></a><b><code class="inline"><span class="w">access</span></code>
</b>
<p>Determines the accessibility of a file.</p>
<pre class="verbatim"><ol><li>	if<span class="s">(</span> <span class="i">POSIX::access</span><span class="s">(</span> <span class="q">&quot;/&quot;</span><span class="cm">,</span> <span class="i">&amp;POSIX::R_OK</span> <span class="s">)</span> <span class="s">)</span><span class="s">{</span></li><li>		<a class="l_k" href="functions/print.html">print</a> <span class="q">&quot;have read permission\n&quot;</span><span class="sc">;</span></li><li>	<span class="s">}</span></li></ol></pre><p>Returns <code class="inline"><a class="l_k" href="functions/undef.html">undef</a></code> on failure.  Note: do not use <code class="inline"><span class="i">access</span><span class="s">(</span><span class="s">)</span></code>
 for
security purposes.  Between the <code class="inline"><span class="i">access</span><span class="s">(</span><span class="s">)</span></code>
 call and the operation
you are preparing for the permissions might change: a classic
<i>race condition</i>.</p>
</li>
<li><a name="acos"></a><b><code class="inline"><span class="w">acos</span></code>
</b>
<p>This is identical to the C function <code class="inline"><span class="i">acos</span><span class="s">(</span><span class="s">)</span></code>
, returning
the arcus cosine of its numerical argument.  See also <a href="Math/Trig.html">Math::Trig</a>.</p>
</li>
<li><a name="acosh"></a><b><code class="inline"><span class="w">acosh</span></code>
</b>
<p>This is identical to the C function <code class="inline"><span class="i">acosh</span><span class="s">(</span><span class="s">)</span></code>
, returning the
hyperbolic arcus cosine of its numerical argument [C99].  See also
<a href="Math/Trig.html">Math::Trig</a>.</p>
</li>
<li><a name="alarm"></a><b><code class="inline"><a class="l_k" href="functions/alarm.html">alarm</a></code></b>
<p>This is identical to Perl's builtin <code class="inline"><a class="l_k" href="functions/alarm.html">alarm()</a></code> function,
either for arming or disarming the <code class="inline"><span class="w">SIGARLM</span></code>
 timer.</p>
</li>
<li><a name="asctime"></a><b><code class="inline"><span class="w">asctime</span></code>
</b>
<p>This is identical to the C function <code class="inline"><span class="i">asctime</span><span class="s">(</span><span class="s">)</span></code>
.  It returns
a string of the form</p>
<pre class="verbatim"><ol><li>	<span class="q">&quot;Fri Jun  2 18:22:13 2000\n\0&quot;</span></li></ol></pre><p>and it is called thusly</p>
<pre class="verbatim"><ol><li>	<span class="i">$asctime</span> = <span class="i">asctime</span><span class="s">(</span><span class="i">$sec</span><span class="cm">,</span> <span class="i">$min</span><span class="cm">,</span> <span class="i">$hour</span><span class="cm">,</span> <span class="i">$mday</span><span class="cm">,</span> <span class="i">$mon</span><span class="cm">,</span></li><li>			   <span class="i">$year</span><span class="cm">,</span> <span class="i">$wday</span><span class="cm">,</span> <span class="i">$yday</span><span class="cm">,</span> <span class="i">$isdst</span><span class="s">)</span><span class="sc">;</span></li></ol></pre><p>The <code class="inline"><span class="i">$mon</span></code>
 is zero-based: January equals <code class="inline"><span class="n">0</span></code>
.  The <code class="inline"><span class="i">$year</span></code>
 is
1900-based: 2001 equals <code class="inline"><span class="n">101</span></code>
.  <code class="inline"><span class="i">$wday</span></code>
 and <code class="inline"><span class="i">$yday</span></code>
 default to zero
(and are usually ignored anyway), and <code class="inline"><span class="i">$isdst</span></code>
 defaults to -1.</p>
</li>
<li><a name="asin"></a><b><code class="inline"><span class="w">asin</span></code>
</b>
<p>This is identical to the C function <code class="inline"><span class="i">asin</span><span class="s">(</span><span class="s">)</span></code>
, returning
the arcus sine of its numerical argument.  See also <a href="Math/Trig.html">Math::Trig</a>.</p>
</li>
<li><a name="asinh"></a><b><code class="inline"><span class="w">asinh</span></code>
</b>
<p>This is identical to the C function <code class="inline"><span class="i">asinh</span><span class="s">(</span><span class="s">)</span></code>
, returning the
hyperbolic arcus sine of its numerical argument [C99].  See also
<a href="Math/Trig.html">Math::Trig</a>.</p>
</li>
<li><a name="assert"></a><b><code class="inline"><span class="w">assert</span></code>
</b>
<p>Unimplemented, but you can use <a href="functions/die.html">die</a> and the <a href="Carp.html">Carp</a> module
to achieve similar things.</p>
</li>
<li><a name="atan"></a><b><code class="inline"><span class="w">atan</span></code>
</b>
<p>This is identical to the C function <code class="inline"><span class="i">atan</span><span class="s">(</span><span class="s">)</span></code>
, returning the
arcus tangent of its numerical argument.  See also <a href="Math/Trig.html">Math::Trig</a>.</p>
</li>
<li><a name="atanh"></a><b><code class="inline"><span class="w">atanh</span></code>
</b>
<p>This is identical to the C function <code class="inline"><span class="i">atanh</span><span class="s">(</span><span class="s">)</span></code>
, returning the
hyperbolic arcus tangent of its numerical argument [C99].  See also
<a href="Math/Trig.html">Math::Trig</a>.</p>
</li>
<li><a name="atan2"></a><b><code class="inline"><a class="l_k" href="functions/atan2.html">atan2</a></code></b>
<p>This is identical to Perl's builtin <code class="inline"><a class="l_k" href="functions/atan2.html">atan2()</a></code> function, returning
the arcus tangent defined by its two numerical arguments, the <i>y</i>
coordinate and the <i>x</i> coordinate.  See also <a href="Math/Trig.html">Math::Trig</a>.</p>
</li>
<li><a name="atexit"></a><b><code class="inline"><span class="w">atexit</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">atexit</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific: use <code class="inline">END <span class="s">{</span><span class="s">}</span></code>
 instead, see <a href="perlmod.html">perlmod</a>.</p>
</li>
<li><a name="atof"></a><b><code class="inline"><span class="w">atof</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">atof</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific.  Perl converts strings to numbers transparently.
If you need to force a scalar to a number, add a zero to it.</p>
</li>
<li><a name="atoi"></a><b><code class="inline"><span class="w">atoi</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">atoi</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific.  Perl converts strings to numbers transparently.
If you need to force a scalar to a number, add a zero to it.
If you need to have just the integer part, see <a href="functions/int.html">int</a>.</p>
</li>
<li><a name="atol"></a><b><code class="inline"><span class="w">atol</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">atol</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific.  Perl converts strings to numbers transparently.
If you need to force a scalar to a number, add a zero to it.
If you need to have just the integer part, see <a href="functions/int.html">int</a>.</p>
</li>
<li><a name="bsearch"></a><b><code class="inline"><span class="w">bsearch</span></code>
</b>
<p><code class="inline"><span class="i">bsearch</span><span class="s">(</span><span class="s">)</span></code>
 not supplied.  For doing binary search on wordlists,
see <a href="Search/Dict.html">Search::Dict</a>.</p>
</li>
<li><a name="calloc"></a><b><code class="inline"><span class="w">calloc</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">calloc</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific.  Perl does memory management transparently.</p>
</li>
<li><a name="cbrt"></a><b><code class="inline"><span class="w">cbrt</span></code>
</b>
<p>The cube root [C99].</p>
</li>
<li><a name="ceil"></a><b><code class="inline"><span class="w">ceil</span></code>
</b>
<p>This is identical to the C function <code class="inline"><span class="i">ceil</span><span class="s">(</span><span class="s">)</span></code>
, returning the smallest
integer value greater than or equal to the given numerical argument.</p>
</li>
<li><a name="chdir"></a><b><code class="inline"><a class="l_k" href="functions/chdir.html">chdir</a></code></b>
<p>This is identical to Perl's builtin <code class="inline"><a class="l_k" href="functions/chdir.html">chdir()</a></code> function, allowing
one to change the working (default) directory, see <a href="functions/chdir.html">chdir</a>.</p>
</li>
<li><a name="chmod"></a><b><code class="inline"><a class="l_k" href="functions/chmod.html">chmod</a></code></b>
<p>This is identical to Perl's builtin <code class="inline"><a class="l_k" href="functions/chmod.html">chmod()</a></code> function, allowing
one to change file and directory permissions, see <a href="functions/chmod.html">chmod</a>.</p>
</li>
<li><a name="chown"></a><b><code class="inline"><a class="l_k" href="functions/chown.html">chown</a></code></b>
<p>This is identical to Perl's builtin <code class="inline"><a class="l_k" href="functions/chown.html">chown()</a></code> function, allowing one
to change file and directory owners and groups, see <a href="functions/chown.html">chown</a>.</p>
</li>
<li><a name="clearerr"></a><b><code class="inline"><span class="w">clearerr</span></code>
</b>
<p>Not implemented.  Use the method <code class="inline"><span class="i">IO::Handle::clearerr</span><span class="s">(</span><span class="s">)</span></code>
 instead, to reset the error
state (if any) and EOF state (if any) of the given stream.</p>
</li>
<li><a name="clock"></a><b><code class="inline"><span class="w">clock</span></code>
</b>
<p>This is identical to the C function <code class="inline"><span class="i">clock</span><span class="s">(</span><span class="s">)</span></code>
, returning the
amount of spent processor time in microseconds.</p>
</li>
<li><a name="close"></a><b><code class="inline"><a class="l_k" href="functions/close.html">close</a></code></b>
<p>Close the file.  This uses file descriptors such as those obtained by calling
<code class="inline"><span class="w">POSIX::open</span></code>
.</p>
<pre class="verbatim"><ol><li>	<span class="i">$fd</span> = <span class="i">POSIX::open</span><span class="s">(</span> <span class="q">&quot;foo&quot;</span><span class="cm">,</span> <span class="i">&amp;POSIX::O_RDONLY</span> <span class="s">)</span><span class="sc">;</span></li><li>	<span class="i">POSIX::close</span><span class="s">(</span> <span class="i">$fd</span> <span class="s">)</span><span class="sc">;</span></li></ol></pre><p>Returns <code class="inline"><a class="l_k" href="functions/undef.html">undef</a></code> on failure.</p>
<p>See also <a href="functions/close.html">close</a>.</p>
</li>
<li><a name="closedir"></a><b><code class="inline"><a class="l_k" href="functions/closedir.html">closedir</a></code></b>
<p>This is identical to Perl's builtin <code class="inline"><a class="l_k" href="functions/closedir.html">closedir()</a></code> function for closing
a directory handle, see <a href="functions/closedir.html">closedir</a>.</p>
</li>
<li><a name="cos"></a><b><code class="inline"><a class="l_k" href="functions/cos.html">cos</a></code></b>
<p>This is identical to Perl's builtin <code class="inline"><a class="l_k" href="functions/cos.html">cos()</a></code> function, for returning
the cosine of its numerical argument, see <a href="functions/cos.html">cos</a>.
See also <a href="Math/Trig.html">Math::Trig</a>.</p>
</li>
<li><a name="cosh"></a><b><code class="inline"><span class="w">cosh</span></code>
</b>
<p>This is identical to the C function <code class="inline"><span class="i">cosh</span><span class="s">(</span><span class="s">)</span></code>
, for returning
the hyperbolic cosine of its numeric argument.  See also <a href="Math/Trig.html">Math::Trig</a>.</p>
</li>
<li><a name="copysign"></a><b><code class="inline"><span class="w">copysign</span></code>
</b>
<p>Returns <code class="inline"><span class="w">x</span></code>
 but with the sign of <code class="inline"><a class="l_k" href="functions/y.html">y</a></code> [C99].</p>
<pre class="verbatim"><ol><li> <span class="i">$x_with_sign_of_y</span> = <span class="i">POSIX::copysign</span><span class="s">(</span><span class="i">$x</span><span class="cm">,</span> <span class="i">$y</span><span class="s">)</span><span class="sc">;</span></li></ol></pre><p>See also <a href="#signbit">signbit</a>.</p>
</li>
<li><a name="creat"></a><b><code class="inline"><span class="w">creat</span></code>
</b>
<p>Create a new file.  This returns a file descriptor like the ones returned by
<code class="inline"><span class="w">POSIX::open</span></code>
.  Use <code class="inline"><span class="w">POSIX::close</span></code>
 to close the file.</p>
<pre class="verbatim"><ol><li>	<span class="i">$fd</span> = <span class="i">POSIX::creat</span><span class="s">(</span> <span class="q">&quot;foo&quot;</span><span class="cm">,</span> <span class="n">0611</span> <span class="s">)</span><span class="sc">;</span></li><li>	<span class="i">POSIX::close</span><span class="s">(</span> <span class="i">$fd</span> <span class="s">)</span><span class="sc">;</span></li></ol></pre><p>See also <a href="functions/sysopen.html">sysopen</a> and its <code class="inline"><span class="w">O_CREAT</span></code>
 flag.</p>
</li>
<li><a name="ctermid"></a><b><code class="inline"><span class="w">ctermid</span></code>
</b>
<p>Generates the path name for the controlling terminal.</p>
<pre class="verbatim"><ol><li>	<span class="i">$path</span> = <span class="i">POSIX::ctermid</span><span class="s">(</span><span class="s">)</span><span class="sc">;</span></li></ol></pre></li>
<li><a name="ctime"></a><b><code class="inline"><span class="w">ctime</span></code>
</b>
<p>This is identical to the C function <code class="inline"><span class="i">ctime</span><span class="s">(</span><span class="s">)</span></code>
 and equivalent
to <code class="inline"><span class="i">asctime</span><span class="s">(</span><a class="l_k" href="functions/localtime.html">localtime</a><span class="s">(</span>...<span class="s">)</span><span class="s">)</span></code>
, see <a href="#asctime">asctime</a> and <a href="#localtime">localtime</a>.</p>
</li>
<li><a name="cuserid"></a><b><code class="inline"><span class="w">cuserid</span></code>
</b>
<p>Get the login name of the owner of the current process.</p>
<pre class="verbatim"><ol><li>	<span class="i">$name</span> = <span class="i">POSIX::cuserid</span><span class="s">(</span><span class="s">)</span><span class="sc">;</span></li></ol></pre></li>
<li><a name="difftime"></a><b><code class="inline"><span class="w">difftime</span></code>
</b>
<p>This is identical to the C function <code class="inline"><span class="i">difftime</span><span class="s">(</span><span class="s">)</span></code>
, for returning
the time difference (in seconds) between two times (as returned
by <code class="inline"><a class="l_k" href="functions/time.html">time()</a></code>), see <a href="#time">time</a>.</p>
</li>
<li><a name="div"></a><b><code class="inline"><span class="w">div</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">div</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific, use <a href="functions/int.html">int</a> on the usual <code class="inline">/</code> division and
the modulus <code class="inline"><span class="i">%</span></code>
.</p>
</li>
<li><a name="dup"></a><b><code class="inline"><span class="w">dup</span></code>
</b>
<p>This is similar to the C function <code class="inline"><span class="i">dup</span><span class="s">(</span><span class="s">)</span></code>
, for duplicating a file
descriptor.</p>
<p>This uses file descriptors such as those obtained by calling
<code class="inline"><span class="w">POSIX::open</span></code>
.</p>
<p>Returns <code class="inline"><a class="l_k" href="functions/undef.html">undef</a></code> on failure.</p>
</li>
<li><a name="dup2"></a><b><code class="inline"><span class="w">dup2</span></code>
</b>
<p>This is similar to the C function <code class="inline"><span class="i">dup2</span><span class="s">(</span><span class="s">)</span></code>
, for duplicating a file
descriptor to an another known file descriptor.</p>
<p>This uses file descriptors such as those obtained by calling
<code class="inline"><span class="w">POSIX::open</span></code>
.</p>
<p>Returns <code class="inline"><a class="l_k" href="functions/undef.html">undef</a></code> on failure.</p>
</li>
<li><a name="erf"></a><b><code class="inline"><span class="w">erf</span></code>
</b>
<p>The error function [C99].</p>
</li>
<li><a name="erfc"></a><b><code class="inline"><span class="w">erfc</span></code>
</b>
<p>The complementary error function [C99].</p>
</li>
<li><a name="errno"></a><b><code class="inline"><span class="w">errno</span></code>
</b>
<p>Returns the value of errno.</p>
<pre class="verbatim"><ol><li>	<span class="i">$errno</span> = <span class="i">POSIX::errno</span><span class="s">(</span><span class="s">)</span><span class="sc">;</span></li></ol></pre><p>This identical to the numerical values of the <code class="inline"><span class="i">$!</span></code>
, see <a href="perlvar.html#%24ERRNO">$ERRNO in perlvar</a>.</p>
</li>
<li><a name="execl"></a><b><code class="inline"><span class="w">execl</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">execl</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific, see <a href="functions/exec.html">exec</a>.</p>
</li>
<li><a name="execle"></a><b><code class="inline"><span class="w">execle</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">execle</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific, see <a href="functions/exec.html">exec</a>.</p>
</li>
<li><a name="execlp"></a><b><code class="inline"><span class="w">execlp</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">execlp</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific, see <a href="functions/exec.html">exec</a>.</p>
</li>
<li><a name="execv"></a><b><code class="inline"><span class="w">execv</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">execv</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific, see <a href="functions/exec.html">exec</a>.</p>
</li>
<li><a name="execve"></a><b><code class="inline"><span class="w">execve</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">execve</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific, see <a href="functions/exec.html">exec</a>.</p>
</li>
<li><a name="execvp"></a><b><code class="inline"><span class="w">execvp</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">execvp</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific, see <a href="functions/exec.html">exec</a>.</p>
</li>
<li><a name="exit"></a><b><code class="inline"><a class="l_k" href="functions/exit.html">exit</a></code></b>
<p>This is identical to Perl's builtin <code class="inline"><a class="l_k" href="functions/exit.html">exit()</a></code> function for exiting the
program, see <a href="functions/exit.html">exit</a>.</p>
</li>
<li><a name="exp"></a><b><code class="inline"><a class="l_k" href="functions/exp.html">exp</a></code></b>
<p>This is identical to Perl's builtin <code class="inline"><a class="l_k" href="functions/exp.html">exp()</a></code> function for
returning the exponent (<i>e</i>-based) of the numerical argument,
see <a href="functions/exp.html">exp</a>.</p>
</li>
<li><a name="expm1"></a><b><code class="inline"><span class="w">expm1</span></code>
</b>
<p>Equivalent to <code class="inline"><a class="l_k" href="functions/exp.html">exp</a><span class="s">(</span><span class="w">x</span><span class="s">)</span> - <span class="n">1</span></code>
, but more precise for small argument values [C99].</p>
<p>See also <a href="#log1p">log1p</a>.</p>
</li>
<li><a name="fabs"></a><b><code class="inline"><span class="w">fabs</span></code>
</b>
<p>This is identical to Perl's builtin <code class="inline"><a class="l_k" href="functions/abs.html">abs()</a></code> function for returning
the absolute value of the numerical argument, see <a href="functions/abs.html">abs</a>.</p>
</li>
<li><a name="fclose"></a><b><code class="inline"><span class="w">fclose</span></code>
</b>
<p>Not implemented.  Use method <code class="inline"><span class="i">IO::Handle::close</span><span class="s">(</span><span class="s">)</span></code>
 instead, or see <a href="functions/close.html">close</a>.</p>
</li>
<li><a name="fcntl"></a><b><code class="inline"><a class="l_k" href="functions/fcntl.html">fcntl</a></code></b>
<p>This is identical to Perl's builtin <code class="inline"><a class="l_k" href="functions/fcntl.html">fcntl()</a></code> function,
see <a href="functions/fcntl.html">fcntl</a>.</p>
</li>
<li><a name="fdopen"></a><b><code class="inline"><span class="w">fdopen</span></code>
</b>
<p>Not implemented.  Use method <code class="inline"><span class="i">IO::Handle::new_from_fd</span><span class="s">(</span><span class="s">)</span></code>
 instead, or see <a href="functions/open.html">open</a>.</p>
</li>
<li><a name="feof"></a><b><code class="inline"><span class="w">feof</span></code>
</b>
<p>Not implemented.  Use method <code class="inline"><span class="i">IO::Handle::eof</span><span class="s">(</span><span class="s">)</span></code>
 instead, or see <a href="functions/eof.html">eof</a>.</p>
</li>
<li><a name="ferror"></a><b><code class="inline"><span class="w">ferror</span></code>
</b>
<p>Not implemented.  Use method <code class="inline"><span class="i">IO::Handle::error</span><span class="s">(</span><span class="s">)</span></code>
 instead.</p>
</li>
<li><a name="fflush"></a><b><code class="inline"><span class="w">fflush</span></code>
</b>
<p>Not implemented.  Use method <code class="inline"><span class="i">IO::Handle::flush</span><span class="s">(</span><span class="s">)</span></code>
 instead.
See also <code class="inline"><a href="perlvar.html#%24OUTPUT_AUTOFLUSH">$OUTPUT_AUTOFLUSH in perlvar</a></code>.</p>
</li>
<li><a name="fgetc"></a><b><code class="inline"><span class="w">fgetc</span></code>
</b>
<p>Not implemented.  Use method <code class="inline"><span class="i">IO::Handle::getc</span><span class="s">(</span><span class="s">)</span></code>
 instead, or see <a href="functions/read.html">read</a>.</p>
</li>
<li><a name="fgetpos"></a><b><code class="inline"><span class="w">fgetpos</span></code>
</b>
<p>Not implemented.  Use method <code class="inline"><span class="i">IO::Seekable::getpos</span><span class="s">(</span><span class="s">)</span></code>
 instead, or see <a href="functions/seek.html">seek</a>.</p>
</li>
<li><a name="fgets"></a><b><code class="inline"><span class="w">fgets</span></code>
</b>
<p>Not implemented.  Use method <code class="inline"><span class="i">IO::Handle::gets</span><span class="s">(</span><span class="s">)</span></code>
 instead.  Similar to &lt;&gt;, also known
as <a href="functions/readline.html">readline</a>.</p>
</li>
<li><a name="fileno"></a><b><code class="inline"><a class="l_k" href="functions/fileno.html">fileno</a></code></b>
<p>Not implemented.  Use method <code class="inline"><span class="i">IO::Handle::fileno</span><span class="s">(</span><span class="s">)</span></code>
 instead, or see <a href="functions/fileno.html">fileno</a>.</p>
</li>
<li><a name="floor"></a><b><code class="inline"><span class="w">floor</span></code>
</b>
<p>This is identical to the C function <code class="inline"><span class="i">floor</span><span class="s">(</span><span class="s">)</span></code>
, returning the largest
integer value less than or equal to the numerical argument.</p>
</li>
<li><a name="fdim"></a><b><code class="inline"><span class="w">fdim</span></code>
</b>
<p>"Positive difference", <code class="inline"><span class="w">x</span> - <span class="q">y</span></code>
 if <code class="inline"><span class="w">x</span> &gt; <span class="q">y</span></code>
, zero otherwise [C99].</p>
</li>
<li><a name="fegetround"></a><b><code class="inline"><span class="w">fegetround</span></code>
</b>
<p>Returns the current floating point rounding mode, one of</p>
<pre class="verbatim"><ol><li>  <span class="w">FE_TONEAREST</span> <span class="w">FE_TOWARDZERO</span> <span class="w">FE_UPWARD</span> <span class="w">FE_UPWARD</span></li></ol></pre><p><code class="inline"><span class="w">FE_TONEAREST</span></code>
 is like <a href="#round">round</a>, <code class="inline"><span class="w">FE_TOWARDZERO</span></code>
 is like <a href="#trunc">trunc</a> [C99].</p>
</li>
<li><a name="fesetround"></a><b><code class="inline"><span class="w">fesetround</span></code>
</b>
<p>Sets the floating point rounding mode, see <a href="#fegetround">fegetround</a> [C99].</p>
</li>
<li><a name="fma"></a><b><code class="inline"><span class="w">fma</span></code>
</b>
<p>"Fused multiply-add", <code class="inline"><span class="w">x</span> * <span class="q">y + z</span></code>
, possibly faster (and less lossy)
than the explicit two operations [C99].</p>
<pre class="verbatim"><ol><li> <a class="l_k" href="functions/my.html">my</a> <span class="i">$fused</span> = <span class="i">POSIX::fma</span><span class="s">(</span><span class="i">$x</span><span class="cm">,</span> <span class="i">$y</span><span class="cm">,</span> <span class="i">$z</span><span class="s">)</span><span class="sc">;</span></li></ol></pre></li>
<li><a name="fmax"></a><b><code class="inline"><span class="w">fmax</span></code>
</b>
<p>Maximum of <code class="inline"><span class="w">x</span></code>
 and <code class="inline"><a class="l_k" href="functions/y.html">y</a></code>, except when either is <code class="inline"><span class="w">NaN</span></code>
, returns the other [C99].</p>
<pre class="verbatim"><ol><li> <a class="l_k" href="functions/my.html">my</a> <span class="i">$min</span> = <span class="i">POSIX::fmax</span><span class="s">(</span><span class="i">$x</span><span class="cm">,</span> <span class="i">$y</span><span class="s">)</span><span class="sc">;</span></li></ol></pre></li>
<li><a name="fmin"></a><b><code class="inline"><span class="w">fmin</span></code>
</b>
<p>Minimum of <code class="inline"><span class="w">x</span></code>
 and <code class="inline"><a class="l_k" href="functions/y.html">y</a></code>, except when either is <code class="inline"><span class="w">NaN</span></code>
, returns the other [C99].</p>
<pre class="verbatim"><ol><li> <a class="l_k" href="functions/my.html">my</a> <span class="i">$min</span> = <span class="i">POSIX::fmin</span><span class="s">(</span><span class="i">$x</span><span class="cm">,</span> <span class="i">$y</span><span class="s">)</span><span class="sc">;</span></li></ol></pre></li>
<li><a name="fmod"></a><b><code class="inline"><span class="w">fmod</span></code>
</b>
<p>This is identical to the C function <code class="inline"><span class="i">fmod</span><span class="s">(</span><span class="s">)</span></code>
.</p>
<pre class="verbatim"><ol><li>	<span class="i">$r</span> = <span class="i">fmod</span><span class="s">(</span><span class="i">$x</span><span class="cm">,</span> <span class="i">$y</span><span class="s">)</span><span class="sc">;</span></li></ol></pre><p>It returns the remainder <code class="inline"><span class="i">$r</span> = <span class="i">$x</span> - <span class="i">$n</span>*<span class="i">$y</span></code>
, where <code class="inline"><span class="i">$n</span> = <span class="i">trunc</span><span class="s">(</span><span class="i">$x</span>/<span class="i">$y</span><span class="s">)</span></code>
.
The <code class="inline"><span class="i">$r</span></code>
 has the same sign as <code class="inline"><span class="i">$x</span></code>
 and magnitude (absolute value)
less than the magnitude of <code class="inline"><span class="i">$y</span></code>
.</p>
</li>
<li><a name="fopen"></a><b><code class="inline"><span class="w">fopen</span></code>
</b>
<p>Not implemented.  Use method <code class="inline"><span class="i">IO::File::open</span><span class="s">(</span><span class="s">)</span></code>
 instead, or see <a href="functions/open.html">open</a>.</p>
</li>
<li><a name="fork"></a><b><code class="inline"><a class="l_k" href="functions/fork.html">fork</a></code></b>
<p>This is identical to Perl's builtin <code class="inline"><a class="l_k" href="functions/fork.html">fork()</a></code> function
for duplicating the current process, see <a href="functions/fork.html">fork</a>
and <a href="perlfork.html">perlfork</a> if you are in Windows.</p>
</li>
<li><a name="fpathconf"></a><b><code class="inline"><span class="w">fpathconf</span></code>
</b>
<p>Retrieves the value of a configurable limit on a file or directory.  This
uses file descriptors such as those obtained by calling <code class="inline"><span class="w">POSIX::open</span></code>
.</p>
<p>The following will determine the maximum length of the longest allowable
pathname on the filesystem which holds <i>/var/foo</i>.</p>
<pre class="verbatim"><ol><li>	<span class="i">$fd</span> = <span class="i">POSIX::open</span><span class="s">(</span> <span class="q">&quot;/var/foo&quot;</span><span class="cm">,</span> <span class="i">&amp;POSIX::O_RDONLY</span> <span class="s">)</span><span class="sc">;</span></li><li>	<span class="i">$path_max</span> = <span class="i">POSIX::fpathconf</span><span class="s">(</span><span class="i">$fd</span><span class="cm">,</span> <span class="i">&amp;POSIX::_PC_PATH_MAX</span><span class="s">)</span><span class="sc">;</span></li></ol></pre><p>Returns <code class="inline"><a class="l_k" href="functions/undef.html">undef</a></code> on failure.</p>
</li>
<li><a name="fpclassify"></a><b><code class="inline"><span class="w">fpclassify</span></code>
</b>
<p>Returns one of</p>
<pre class="verbatim"><ol><li>  <span class="w">FP_NORMAL</span> <span class="w">FP_ZERO</span> <span class="w">FP_SUBNORMAL</span> <span class="w">FP_INFINITE</span> <span class="w">FP_NAN</span></li></ol></pre><p>telling the class of the argument [C99].  <code class="inline"><span class="w">FP_INFINITE</span></code>
 is positive
or negative infinity, <code class="inline"><span class="w">FP_NAN</span></code>
 is not-a-number.  <code class="inline"><span class="w">FP_SUBNORMAL</span></code>

means subnormal numbers (also known as denormals), very small numbers
with low precision. <code class="inline"><span class="w">FP_ZERO</span></code>
 is zero.  <code class="inline"><span class="w">FP_NORMAL</span></code>
 is all the rest.</p>
</li>
<li><a name="fprintf"></a><b><code class="inline"><span class="w">fprintf</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">fprintf</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific, see <a href="functions/printf.html">printf</a> instead.</p>
</li>
<li><a name="fputc"></a><b><code class="inline"><span class="w">fputc</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">fputc</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific, see <a href="functions/print.html">print</a> instead.</p>
</li>
<li><a name="fputs"></a><b><code class="inline"><span class="w">fputs</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">fputs</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific, see <a href="functions/print.html">print</a> instead.</p>
</li>
<li><a name="fread"></a><b><code class="inline"><span class="w">fread</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">fread</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific, see <a href="functions/read.html">read</a> instead.</p>
</li>
<li><a name="free"></a><b><code class="inline"><span class="w">free</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">free</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific.  Perl does memory management transparently.</p>
</li>
<li><a name="freopen"></a><b><code class="inline"><span class="w">freopen</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">freopen</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific, see <a href="functions/open.html">open</a> instead.</p>
</li>
<li><a name="frexp"></a><b><code class="inline"><span class="w">frexp</span></code>
</b>
<p>Return the mantissa and exponent of a floating-point number.</p>
<pre class="verbatim"><ol><li>	<span class="s">(</span><span class="i">$mantissa</span><span class="cm">,</span> <span class="i">$exponent</span><span class="s">)</span> = <span class="i">POSIX::frexp</span><span class="s">(</span> <span class="n">1.234e56</span> <span class="s">)</span><span class="sc">;</span></li></ol></pre></li>
<li><a name="fscanf"></a><b><code class="inline"><span class="w">fscanf</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">fscanf</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific, use &lt;&gt; and regular expressions instead.</p>
</li>
<li><a name="fseek"></a><b><code class="inline"><span class="w">fseek</span></code>
</b>
<p>Not implemented.  Use method <code class="inline"><span class="i">IO::Seekable::seek</span><span class="s">(</span><span class="s">)</span></code>
 instead, or see <a href="functions/seek.html">seek</a>.</p>
</li>
<li><a name="fsetpos"></a><b><code class="inline"><span class="w">fsetpos</span></code>
</b>
<p>Not implemented.  Use method <code class="inline"><span class="i">IO::Seekable::setpos</span><span class="s">(</span><span class="s">)</span></code>
 instead, or seek <a href="functions/seek.html">seek</a>.</p>
</li>
<li><a name="fstat"></a><b><code class="inline"><span class="w">fstat</span></code>
</b>
<p>Get file status.  This uses file descriptors such as those obtained by
calling <code class="inline"><span class="w">POSIX::open</span></code>
.  The data returned is identical to the data from
Perl's builtin <code class="inline"><a class="l_k" href="functions/stat.html">stat</a></code> function.</p>
<pre class="verbatim"><ol><li>	<span class="i">$fd</span> = <span class="i">POSIX::open</span><span class="s">(</span> <span class="q">&quot;foo&quot;</span><span class="cm">,</span> <span class="i">&amp;POSIX::O_RDONLY</span> <span class="s">)</span><span class="sc">;</span></li><li>	<span class="i">@stats</span> = <span class="i">POSIX::fstat</span><span class="s">(</span> <span class="i">$fd</span> <span class="s">)</span><span class="sc">;</span></li></ol></pre></li>
<li><a name="fsync"></a><b><code class="inline"><span class="w">fsync</span></code>
</b>
<p>Not implemented.  Use method <code class="inline"><span class="i">IO::Handle::sync</span><span class="s">(</span><span class="s">)</span></code>
 instead.</p>
</li>
<li><a name="ftell"></a><b><code class="inline"><span class="w">ftell</span></code>
</b>
<p>Not implemented.  Use method <code class="inline"><span class="i">IO::Seekable::tell</span><span class="s">(</span><span class="s">)</span></code>
 instead, or see <a href="functions/tell.html">tell</a>.</p>
</li>
<li><a name="fwrite"></a><b><code class="inline"><span class="w">fwrite</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">fwrite</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific, see <a href="functions/print.html">print</a> instead.</p>
</li>
<li><a name="getc"></a><b><code class="inline"><a class="l_k" href="functions/getc.html">getc</a></code></b>
<p>This is identical to Perl's builtin <code class="inline"><a class="l_k" href="functions/getc.html">getc()</a></code> function,
see <a href="functions/getc.html">getc</a>.</p>
</li>
<li><a name="getchar"></a><b><code class="inline"><span class="w">getchar</span></code>
</b>
<p>Returns one character from STDIN.  Identical to Perl's <code class="inline"><a class="l_k" href="functions/getc.html">getc()</a></code>,
see <a href="functions/getc.html">getc</a>.</p>
</li>
<li><a name="getcwd"></a><b><code class="inline"><span class="w">getcwd</span></code>
</b>
<p>Returns the name of the current working directory.
See also <a href="Cwd.html">Cwd</a>.</p>
</li>
<li><a name="getegid"></a><b><code class="inline"><span class="w">getegid</span></code>
</b>
<p>Returns the effective group identifier.  Similar to Perl' s builtin
variable <code class="inline"><span class="i">$(</span></code>
, see <a href="perlvar.html#%24EGID">$EGID in perlvar</a>.</p>
</li>
<li><a name="getenv"></a><b><code class="inline"><span class="w">getenv</span></code>
</b>
<p>Returns the value of the specified environment variable.
The same information is available through the <code class="inline"><span class="i">%ENV</span></code>
 array.</p>
</li>
<li><a name="geteuid"></a><b><code class="inline"><span class="w">geteuid</span></code>
</b>
<p>Returns the effective user identifier.  Identical to Perl's builtin <code class="inline"><span class="i">$&gt;</span></code>

variable, see <a href="perlvar.html#%24EUID">$EUID in perlvar</a>.</p>
</li>
<li><a name="getgid"></a><b><code class="inline"><span class="w">getgid</span></code>
</b>
<p>Returns the user's real group identifier.  Similar to Perl's builtin
variable <code class="inline"><span class="i">$)</span></code>
, see <a href="perlvar.html#%24GID">$GID in perlvar</a>.</p>
</li>
<li><a name="getgrgid"></a><b><code class="inline"><a class="l_k" href="functions/getgrgid.html">getgrgid</a></code></b>
<p>This is identical to Perl's builtin <code class="inline"><a class="l_k" href="functions/getgrgid.html">getgrgid()</a></code> function for
returning group entries by group identifiers, see
<a href="functions/getgrgid.html">getgrgid</a>.</p>
</li>
<li><a name="getgrnam"></a><b><code class="inline"><a class="l_k" href="functions/getgrnam.html">getgrnam</a></code></b>
<p>This is identical to Perl's builtin <code class="inline"><a class="l_k" href="functions/getgrnam.html">getgrnam()</a></code> function for
returning group entries by group names, see <a href="functions/getgrnam.html">getgrnam</a>.</p>
</li>
<li><a name="getgroups"></a><b><code class="inline"><span class="w">getgroups</span></code>
</b>
<p>Returns the ids of the user's supplementary groups.  Similar to Perl's
builtin variable <code class="inline"><span class="i">$)</span></code>
, see <a href="perlvar.html#%24GID">$GID in perlvar</a>.</p>
</li>
<li><a name="getlogin"></a><b><code class="inline"><a class="l_k" href="functions/getlogin.html">getlogin</a></code></b>
<p>This is identical to Perl's builtin <code class="inline"><a class="l_k" href="functions/getlogin.html">getlogin()</a></code> function for
returning the user name associated with the current session, see
<a href="functions/getlogin.html">getlogin</a>.</p>
</li>
<li><a name="getpayload"></a><b><code class="inline"><span class="w">getpayload</span></code>
</b>
<pre class="verbatim"><ol><li>	<a class="l_k" href="functions/use.html">use</a> <span class="w">POSIX</span> <span class="q">&#39;:nan_payload&#39;</span><span class="sc">;</span></li><li>	<span class="i">getpayload</span><span class="s">(</span><span class="i">$var</span><span class="s">)</span></li></ol></pre><p>Returns the <code class="inline"><span class="w">NaN</span></code>
 payload.</p>
<p>Note the API instability warning in <a href="#setpayload">setpayload</a>.</p>
<p>See <a href="#nan">nan</a> for more discussion about <code class="inline"><span class="w">NaN</span></code>
.</p>
</li>
<li><a name="getpgrp"></a><b><code class="inline"><a class="l_k" href="functions/getpgrp.html">getpgrp</a></code></b>
<p>This is identical to Perl's builtin <code class="inline"><a class="l_k" href="functions/getpgrp.html">getpgrp()</a></code> function for
returning the process group identifier of the current process, see
<a href="functions/getpgrp.html">getpgrp</a>.</p>
</li>
<li><a name="getpid"></a><b><code class="inline"><span class="w">getpid</span></code>
</b>
<p>Returns the process identifier.  Identical to Perl's builtin
variable <code class="inline"><span class="i">$$</span></code>
, see <a href="perlvar.html#%24PID">$PID in perlvar</a>.</p>
</li>
<li><a name="getppid"></a><b><code class="inline"><a class="l_k" href="functions/getppid.html">getppid</a></code></b>
<p>This is identical to Perl's builtin <code class="inline"><a class="l_k" href="functions/getppid.html">getppid()</a></code> function for
returning the process identifier of the parent process of the current
process , see <a href="functions/getppid.html">getppid</a>.</p>
</li>
<li><a name="getpwnam"></a><b><code class="inline"><a class="l_k" href="functions/getpwnam.html">getpwnam</a></code></b>
<p>This is identical to Perl's builtin <code class="inline"><a class="l_k" href="functions/getpwnam.html">getpwnam()</a></code> function for
returning user entries by user names, see <a href="functions/getpwnam.html">getpwnam</a>.</p>
</li>
<li><a name="getpwuid"></a><b><code class="inline"><a class="l_k" href="functions/getpwuid.html">getpwuid</a></code></b>
<p>This is identical to Perl's builtin <code class="inline"><a class="l_k" href="functions/getpwuid.html">getpwuid()</a></code> function for
returning user entries by user identifiers, see <a href="functions/getpwuid.html">getpwuid</a>.</p>
</li>
<li><a name="gets"></a><b><code class="inline"><span class="w">gets</span></code>
</b>
<p>Returns one line from <code class="inline"><span class="w">STDIN</span></code>
, similar to &lt;&gt;, also known
as the <code class="inline"><a class="l_k" href="functions/readline.html">readline()</a></code> function, see <a href="functions/readline.html">readline</a>.</p>
<p><b>NOTE</b>: if you have C programs that still use <code class="inline"><span class="i">gets</span><span class="s">(</span><span class="s">)</span></code>
, be very
afraid.  The <code class="inline"><span class="i">gets</span><span class="s">(</span><span class="s">)</span></code>
 function is a source of endless grief because
it has no buffer overrun checks.  It should <b>never</b> be used.  The
<code class="inline"><span class="i">fgets</span><span class="s">(</span><span class="s">)</span></code>
 function should be preferred instead.</p>
</li>
<li><a name="getuid"></a><b><code class="inline"><span class="w">getuid</span></code>
</b>
<p>Returns the user's identifier.  Identical to Perl's builtin <code class="inline"><span class="i">$&lt;</span></code>
 variable,
see <a href="perlvar.html#%24UID">$UID in perlvar</a>.</p>
</li>
<li><a name="gmtime"></a><b><code class="inline"><a class="l_k" href="functions/gmtime.html">gmtime</a></code></b>
<p>This is identical to Perl's builtin <code class="inline"><a class="l_k" href="functions/gmtime.html">gmtime()</a></code> function for
converting seconds since the epoch to a date in Greenwich Mean Time,
see <a href="functions/gmtime.html">gmtime</a>.</p>
</li>
<li><a name="hypot"></a><b><code class="inline"><span class="w">hypot</span></code>
</b>
<p>Equivalent to <code class="inline"><a class="l_k" href="functions/sqrt.html">sqrt</a><span class="s">(</span><span class="w">x</span> * <span class="w">x</span> + <span class="q">y * y)</span></code>
 except more stable on very large
or very small arguments [C99].</p>
</li>
<li><a name="ilogb"></a><b><code class="inline"><span class="w">ilogb</span></code>
</b>
<p>Integer binary logarithm [C99]</p>
<p>For example <code class="inline"><span class="i">ilogb</span><span class="s">(</span><span class="n">20</span><span class="s">)</span></code>
 is 4, as an integer.</p>
<p>See also <a href="#logb">logb</a>.</p>
</li>
<li><a name="Inf"></a><b><code class="inline"><span class="w">Inf</span></code>
</b>
<p>The infinity as a constant:</p>
<pre class="verbatim"><ol><li>   <a class="l_k" href="functions/use.html">use</a> <span class="w">POSIX</span> <span class="q">qw(Inf)</span><span class="sc">;</span></li><li>   <a class="l_k" href="functions/my.html">my</a> <span class="i">$pos_inf</span> = +<span class="w">Inf</span><span class="sc">;</span>  <span class="c"># Or just Inf.</span></li><li>   <a class="l_k" href="functions/my.html">my</a> <span class="i">$neg_inf</span> = -<span class="w">Inf</span><span class="sc">;</span></li></ol></pre><p>See also <a href="#isinf">isinf</a>, and <a href="#fpclassify">fpclassify</a>.</p>
</li>
<li><a name="isalnum"></a><b><code class="inline"><span class="w">isalnum</span></code>
</b>
<p>This function has been removed as of v5.24.  It was very similar to
matching against <code class="inline"><span class="q">qr/ ^ [[:alnum:]]+ $ /x</span></code>
, which you should convert
to use instead.  See <a href="perlrecharclass.html#POSIX-Character-Classes">POSIX Character Classes in perlrecharclass</a>.</p>
</li>
<li><a name="isalpha"></a><b><code class="inline"><span class="w">isalpha</span></code>
</b>
<p>This function has been removed as of v5.24.  It was very similar to
matching against <code class="inline"><span class="q">qr/ ^ [[:alpha:]]+ $ /x</span></code>
, which you should convert
to use instead.  See <a href="perlrecharclass.html#POSIX-Character-Classes">POSIX Character Classes in perlrecharclass</a>.</p>
</li>
<li><a name="isatty"></a><b><code class="inline"><span class="w">isatty</span></code>
</b>
<p>Returns a boolean indicating whether the specified filehandle is connected
to a tty.  Similar to the <code class="inline">-t</code>
 operator, see <a href="functions/-X.html">-X</a>.</p>
</li>
<li><a name="iscntrl"></a><b><code class="inline"><span class="w">iscntrl</span></code>
</b>
<p>This function has been removed as of v5.24.  It was very similar to
matching against <code class="inline"><span class="q">qr/ ^ [[:cntrl:]]+ $ /x</span></code>
, which you should convert
to use instead.  See <a href="perlrecharclass.html#POSIX-Character-Classes">POSIX Character Classes in perlrecharclass</a>.</p>
</li>
<li><a name="isdigit"></a><b><code class="inline"><span class="w">isdigit</span></code>
</b>
<p>This function has been removed as of v5.24.  It was very similar to
matching against <code class="inline"><span class="q">qr/ ^ [[:digit:]]+ $ /x</span></code>
, which you should convert
to use instead.  See <a href="perlrecharclass.html#POSIX-Character-Classes">POSIX Character Classes in perlrecharclass</a>.</p>
</li>
<li><a name="isfinite"></a><b><code class="inline"><span class="w">isfinite</span></code>
</b>
<p>Returns true if the argument is a finite number (that is, not an
infinity, or the not-a-number) [C99].</p>
<p>See also <a href="#isinf">isinf</a>, <a href="#isnan">isnan</a>, and <a href="#fpclassify">fpclassify</a>.</p>
</li>
<li><a name="isgraph"></a><b><code class="inline"><span class="w">isgraph</span></code>
</b>
<p>This function has been removed as of v5.24.  It was very similar to
matching against <code class="inline"><span class="q">qr/ ^ [[:graph:]]+ $ /x</span></code>
, which you should convert
to use instead.  See <a href="perlrecharclass.html#POSIX-Character-Classes">POSIX Character Classes in perlrecharclass</a>.</p>
</li>
<li><a name="isgreater"></a><b><code class="inline"><span class="w">isgreater</span></code>
</b>
<p>(Also <code class="inline"><span class="w">isgreaterequal</span></code>
, <code class="inline"><span class="w">isless</span></code>
, <code class="inline"><span class="w">islessequal</span></code>
, <code class="inline"><span class="w">islessgreater</span></code>
,
<code class="inline"><span class="w">isunordered</span></code>
)</p>
<p>Floating point comparisons which handle the <code class="inline"><span class="w">NaN</span></code>
 [C99].</p>
</li>
<li><a name="isinf"></a><b><code class="inline"><span class="w">isinf</span></code>
</b>
<p>Returns true if the argument is an infinity (positive or negative) [C99].</p>
<p>See also <a href="#Inf">Inf</a>, <a href="#isnan">isnan</a>, <a href="#isfinite">isfinite</a>, and <a href="#fpclassify">fpclassify</a>.</p>
</li>
<li><a name="islower"></a><b><code class="inline"><span class="w">islower</span></code>
</b>
<p>This function has been removed as of v5.24.  It was very similar to
matching against <code class="inline"><span class="q">qr/ ^ [[:lower:]]+ $ /x</span></code>
, which you should convert
to use instead.  See <a href="perlrecharclass.html#POSIX-Character-Classes">POSIX Character Classes in perlrecharclass</a>.</p>
</li>
<li><a name="isnan"></a><b><code class="inline"><span class="w">isnan</span></code>
</b>
<p>Returns true if the argument is <code class="inline"><span class="w">NaN</span></code>
 (not-a-number) [C99].</p>
<p>Note that you cannot test for "<code class="inline"><span class="w">NaN</span></code>
-ness" with</p>
<pre class="verbatim"><ol><li>   <span class="i">$x</span> == <span class="i">$x</span></li></ol></pre><p>since the <code class="inline"><span class="w">NaN</span></code>
 is not equivalent to anything, <b>including itself</b>.</p>
<p>See also <a href="#nan">nan</a>, <a href="#NaN">NaN</a>, <a href="#isinf">isinf</a>, and <a href="#fpclassify">fpclassify</a>.</p>
</li>
<li><a name="isnormal"></a><b><code class="inline"><span class="w">isnormal</span></code>
</b>
<p>Returns true if the argument is normal (that is, not a subnormal/denormal,
and not an infinity, or a not-a-number) [C99].</p>
<p>See also <a href="#isfinite">isfinite</a>, and <a href="#fpclassify">fpclassify</a>.</p>
</li>
<li><a name="isprint"></a><b><code class="inline"><span class="w">isprint</span></code>
</b>
<p>This function has been removed as of v5.24.  It was very similar to
matching against <code class="inline"><span class="q">qr/ ^ [[:print:]]+ $ /x</span></code>
, which you should convert
to use instead.  See <a href="perlrecharclass.html#POSIX-Character-Classes">POSIX Character Classes in perlrecharclass</a>.</p>
</li>
<li><a name="ispunct"></a><b><code class="inline"><span class="w">ispunct</span></code>
</b>
<p>This function has been removed as of v5.24.  It was very similar to
matching against <code class="inline"><span class="q">qr/ ^ [[:punct:]]+ $ /x</span></code>
, which you should convert
to use instead.  See <a href="perlrecharclass.html#POSIX-Character-Classes">POSIX Character Classes in perlrecharclass</a>.</p>
</li>
<li><a name="issignaling"></a><b><code class="inline"><span class="w">issignaling</span></code>
</b>
<pre class="verbatim"><ol><li>	<a class="l_k" href="functions/use.html">use</a> <span class="w">POSIX</span> <span class="q">&#39;:nan_payload&#39;</span><span class="sc">;</span></li><li>	<span class="i">issignaling</span><span class="s">(</span><span class="i">$var</span><span class="cm">,</span> <span class="i">$payload</span><span class="s">)</span></li></ol></pre><p>Return true if the argument is a <i>signaling</i> NaN.</p>
<p>Note the API instability warning in <a href="#setpayload">setpayload</a>.</p>
<p>See <a href="#nan">nan</a> for more discussion about <code class="inline"><span class="w">NaN</span></code>
.</p>
</li>
<li><a name="isspace"></a><b><code class="inline"><span class="w">isspace</span></code>
</b>
<p>This function has been removed as of v5.24.  It was very similar to
matching against <code class="inline"><span class="q">qr/ ^ [[:space:]]+ $ /x</span></code>
, which you should convert
to use instead.  See <a href="perlrecharclass.html#POSIX-Character-Classes">POSIX Character Classes in perlrecharclass</a>.</p>
</li>
<li><a name="isupper"></a><b><code class="inline"><span class="w">isupper</span></code>
</b>
<p>This function has been removed as of v5.24.  It was very similar to
matching against <code class="inline"><span class="q">qr/ ^ [[:upper:]]+ $ /x</span></code>
, which you should convert
to use instead.  See <a href="perlrecharclass.html#POSIX-Character-Classes">POSIX Character Classes in perlrecharclass</a>.</p>
</li>
<li><a name="isxdigit"></a><b><code class="inline"><span class="w">isxdigit</span></code>
</b>
<p>This function has been removed as of v5.24.  It was very similar to
matching against <code class="inline"><span class="q">qr/ ^ [[:xdigit:]]+ $ /x</span></code>
, which you should
convert to use instead.  See <a href="perlrecharclass.html#POSIX-Character-Classes">POSIX Character Classes in perlrecharclass</a>.</p>
</li>
<li><a name="j0"></a><b><code class="inline"><span class="w">j0</span></code>
</b>
</li>
<li><a name="j1"></a><b><code class="inline"><span class="w">j1</span></code>
</b>
</li>
<li><a name="jn"></a><b><code class="inline"><span class="w">jn</span></code>
</b>
</li>
<li><a name="y0"></a><b><code class="inline"><span class="w">y0</span></code>
</b>
</li>
<li><a name="y1"></a><b><code class="inline"><span class="w">y1</span></code>
</b>
</li>
<li><a name="yn"></a><b><code class="inline"><span class="w">yn</span></code>
</b>
<p>The Bessel function of the first kind of the order zero.</p>
</li>
<li><a name="kill"></a><b><code class="inline"><a class="l_k" href="functions/kill.html">kill</a></code></b>
<p>This is identical to Perl's builtin <code class="inline"><a class="l_k" href="functions/kill.html">kill()</a></code> function for sending
signals to processes (often to terminate them), see <a href="functions/kill.html">kill</a>.</p>
</li>
<li><a name="labs"></a><b><code class="inline"><span class="w">labs</span></code>
</b>
<p>Not implemented.  (For returning absolute values of long integers.)
<code class="inline"><span class="i">labs</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific, see <a href="functions/abs.html">abs</a> instead.</p>
</li>
<li><a name="lchown"></a><b><code class="inline"><span class="w">lchown</span></code>
</b>
<p>This is identical to the C function, except the order of arguments is
consistent with Perl's builtin <code class="inline"><a class="l_k" href="functions/chown.html">chown()</a></code> with the added restriction
of only one path, not a list of paths.  Does the same thing as the
<code class="inline"><a class="l_k" href="functions/chown.html">chown()</a></code> function but changes the owner of a symbolic link instead
of the file the symbolic link points to.</p>
<pre class="verbatim"><ol><li> <span class="i">POSIX::lchown</span><span class="s">(</span><span class="i">$uid</span><span class="cm">,</span> <span class="i">$gid</span><span class="cm">,</span> <span class="i">$file_path</span><span class="s">)</span><span class="sc">;</span></li></ol></pre></li>
<li><a name="ldexp"></a><b><code class="inline"><span class="w">ldexp</span></code>
</b>
<p>This is identical to the C function <code class="inline"><span class="i">ldexp</span><span class="s">(</span><span class="s">)</span></code>

for multiplying floating point numbers with powers of two.</p>
<pre class="verbatim"><ol><li>	<span class="i">$x_quadrupled</span> = <span class="i">POSIX::ldexp</span><span class="s">(</span><span class="i">$x</span><span class="cm">,</span> <span class="n">2</span><span class="s">)</span><span class="sc">;</span></li></ol></pre></li>
<li><a name="ldiv"></a><b><code class="inline"><span class="w">ldiv</span></code>
</b>
<p>Not implemented.  (For computing dividends of long integers.)
<code class="inline"><span class="i">ldiv</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific, use <code class="inline">/</code> and <code class="inline"><a class="l_k" href="functions/int.html">int()</a></code> instead.</p>
</li>
<li><a name="lgamma"></a><b><code class="inline"><span class="w">lgamma</span></code>
</b>
<p>The logarithm of the Gamma function [C99].</p>
<p>See also <a href="#tgamma">tgamma</a>.</p>
</li>
<li><a name="log1p"></a><b><code class="inline"><span class="w">log1p</span></code>
</b>
<p>Equivalent to <code class="inline"><a class="l_k" href="functions/log.html">log</a><span class="s">(</span><span class="n">1</span> + <span class="w">x</span><span class="s">)</span></code>
, but more stable results for small argument
values [C99].</p>
</li>
<li><a name="log2"></a><b><code class="inline"><span class="w">log2</span></code>
</b>
<p>Logarithm base two [C99].</p>
<p>See also <a href="#expm1">expm1</a>.</p>
</li>
<li><a name="logb"></a><b><code class="inline"><span class="w">logb</span></code>
</b>
<p>Integer binary logarithm [C99].</p>
<p>For example <code class="inline"><span class="i">logb</span><span class="s">(</span><span class="n">20</span><span class="s">)</span></code>
 is 4, as a floating point number.</p>
<p>See also <a href="#ilogb">ilogb</a>.</p>
</li>
<li><a name="link"></a><b><code class="inline"><a class="l_k" href="functions/link.html">link</a></code></b>
<p>This is identical to Perl's builtin <code class="inline"><a class="l_k" href="functions/link.html">link()</a></code> function
for creating hard links into files, see <a href="functions/link.html">link</a>.</p>
</li>
<li><a name="localeconv"></a><b><code class="inline"><span class="w">localeconv</span></code>
</b>
<p>Get numeric formatting information.  Returns a reference to a hash
containing the current underlying locale's formatting values.  Users of this function
should also read <a href="perllocale.html">perllocale</a>, which provides a comprehensive
discussion of Perl locale handling, including
<a href="perllocale.html#The-localeconv-function">a section devoted to this function</a>.</p>
<p>Here is how to query the database for the <b>de</b> (Deutsch or German) locale.</p>
<pre class="verbatim"><ol><li>	<a class="l_k" href="functions/my.html">my</a> <span class="i">$loc</span> = <span class="i">POSIX::setlocale</span><span class="s">(</span> <span class="i">&amp;POSIX::LC_ALL</span><span class="cm">,</span> <span class="q">&quot;de&quot;</span> <span class="s">)</span><span class="sc">;</span></li><li>	<a class="l_k" href="functions/print.html">print</a> <span class="q">&quot;Locale: \&quot;$loc\&quot;\n&quot;</span><span class="sc">;</span></li><li>	<a class="l_k" href="functions/my.html">my</a> <span class="i">$lconv</span> = <span class="i">POSIX::localeconv</span><span class="s">(</span><span class="s">)</span><span class="sc">;</span></li><li>	<a class="l_k" href="functions/foreach.html">foreach</a> <a class="l_k" href="functions/my.html">my</a> <span class="i">$property</span> <span class="s">(</span><span class="q">qw(</span></li><li>		<span class="q">decimal_point</span></li><li>		<span class="q">thousands_sep</span></li><li>		<span class="q">grouping</span></li><li>		<span class="q">int_curr_symbol</span></li><li>		<span class="q">currency_symbol</span></li><li>		<span class="q">mon_decimal_point</span></li><li>		<span class="q">mon_thousands_sep</span></li><li>		<span class="q">mon_grouping</span></li><li>		<span class="q">positive_sign</span></li><li>		<span class="q">negative_sign</span></li><li>		<span class="q">int_frac_digits</span></li><li>		<span class="q">frac_digits</span></li><li>		<span class="q">p_cs_precedes</span></li><li>		<span class="q">p_sep_by_space</span></li><li>		<span class="q">n_cs_precedes</span></li><li>		<span class="q">n_sep_by_space</span></li><li>		<span class="q">p_sign_posn</span></li><li>		<span class="q">n_sign_posn</span></li><li>		<span class="q">int_p_cs_precedes</span></li><li>		<span class="q">int_p_sep_by_space</span></li><li>		<span class="q">int_n_cs_precedes</span></li><li>		<span class="q">int_n_sep_by_space</span></li><li>		<span class="q">int_p_sign_posn</span></li><li>		<span class="q">int_n_sign_posn</span></li><li>	<span class="q">)</span><span class="s">)</span></li><li>	<span class="s">{</span></li><li>		<a class="l_k" href="functions/printf.html">printf</a> <span class="q">qq(%s: &quot;%s&quot;,\n)</span><span class="cm">,</span></li><li>			<span class="i">$property</span><span class="cm">,</span> <span class="i">$lconv</span>-&gt;{<span class="i">$property</span>}<span class="sc">;</span></li><li>	<span class="s">}</span></li></ol></pre><p>The members whose names begin with <code class="inline"><span class="w">int_p_</span></code>
 and <code class="inline"><span class="w">int_n_</span></code>
 were added by
POSIX.1-2008 and are only available on systems that support them.</p>
</li>
<li><a name="localtime"></a><b><code class="inline"><a class="l_k" href="functions/localtime.html">localtime</a></code></b>
<p>This is identical to Perl's builtin <code class="inline"><a class="l_k" href="functions/localtime.html">localtime()</a></code> function for
converting seconds since the epoch to a date see <a href="functions/localtime.html">localtime</a>.</p>
</li>
<li><a name="log"></a><b><code class="inline"><a class="l_k" href="functions/log.html">log</a></code></b>
<p>This is identical to Perl's builtin <code class="inline"><a class="l_k" href="functions/log.html">log()</a></code> function,
returning the natural (<i>e</i>-based) logarithm of the numerical argument,
see <a href="functions/log.html">log</a>.</p>
</li>
<li><a name="log10"></a><b><code class="inline"><span class="w">log10</span></code>
</b>
<p>This is identical to the C function <code class="inline"><span class="i">log10</span><span class="s">(</span><span class="s">)</span></code>
,
returning the 10-base logarithm of the numerical argument.
You can also use</p>
<pre class="verbatim"><ol><li><a name="log10"></a>    sub <span class="m">log10</span> <span class="s">{</span> <a class="l_k" href="functions/log.html">log</a><span class="s">(</span><span class="i">$_</span>[<span class="n">0</span>]<span class="s">)</span> / <a class="l_k" href="functions/log.html">log</a><span class="s">(</span><span class="n">10</span><span class="s">)</span> <span class="s">}</span></li></ol></pre><p>or</p>
<pre class="verbatim"><ol><li><a name="log10"></a>    sub <span class="m">log10</span> <span class="s">{</span> <a class="l_k" href="functions/log.html">log</a><span class="s">(</span><span class="i">$_</span>[<span class="n">0</span>]<span class="s">)</span> / <span class="n">2.30258509299405</span> <span class="s">}</span></li></ol></pre><p>or</p>
<pre class="verbatim"><ol><li><a name="log10"></a>    sub <span class="m">log10</span> <span class="s">{</span> <a class="l_k" href="functions/log.html">log</a><span class="s">(</span><span class="i">$_</span>[<span class="n">0</span>]<span class="s">)</span> * <span class="n">0.434294481903252</span> <span class="s">}</span></li></ol></pre></li>
<li><a name="longjmp"></a><b><code class="inline"><span class="w">longjmp</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">longjmp</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific: use <a href="functions/die.html">die</a> instead.</p>
</li>
<li><a name="lseek"></a><b><code class="inline"><span class="w">lseek</span></code>
</b>
<p>Move the file's read/write position.  This uses file descriptors such as
those obtained by calling <code class="inline"><span class="w">POSIX::open</span></code>
.</p>
<pre class="verbatim"><ol><li>	<span class="i">$fd</span> = <span class="i">POSIX::open</span><span class="s">(</span> <span class="q">&quot;foo&quot;</span><span class="cm">,</span> <span class="i">&amp;POSIX::O_RDONLY</span> <span class="s">)</span><span class="sc">;</span></li><li>	<span class="i">$off_t</span> = <span class="i">POSIX::lseek</span><span class="s">(</span> <span class="i">$fd</span><span class="cm">,</span> <span class="n">0</span><span class="cm">,</span> <span class="i">&amp;POSIX::SEEK_SET</span> <span class="s">)</span><span class="sc">;</span></li></ol></pre><p>Returns <code class="inline"><a class="l_k" href="functions/undef.html">undef</a></code> on failure.</p>
</li>
<li><a name="lrint"></a><b><code class="inline"><span class="w">lrint</span></code>
</b>
<p>Depending on the current floating point rounding mode, rounds the
argument either toward nearest (like <a href="#round">round</a>), toward zero (like
<a href="#trunc">trunc</a>), downward (toward negative infinity), or upward (toward
positive infinity) [C99].</p>
<p>For the rounding mode, see <a href="#fegetround">fegetround</a>.</p>
</li>
<li><a name="lround"></a><b><code class="inline"><span class="w">lround</span></code>
</b>
<p>Like <a href="#round">round</a>, but as integer, as opposed to floating point [C99].</p>
<p>See also <a href="#ceil">ceil</a>, <a href="#floor">floor</a>, <a href="#trunc">trunc</a>.</p>
<p>Owing to an oversight, this is not currently exported by default, or as part of
the <code class="inline"><span class="j">:</span><span class="w">math_h_c99</span></code>
 export tag; importing it must therefore be done by explicit
name.</p>
</li>
<li><a name="malloc"></a><b><code class="inline"><span class="w">malloc</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">malloc</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific.  Perl does memory management transparently.</p>
</li>
<li><a name="mblen"></a><b><code class="inline"><span class="w">mblen</span></code>
</b>
<p>This is identical to the C function <code class="inline"><span class="i">mblen</span><span class="s">(</span><span class="s">)</span></code>
.</p>
<p>Core Perl does not have any support for the wide and multibyte
characters of the C standards, except under UTF-8 locales, so this might
be a rather useless function.</p>
<p>However, Perl supports Unicode, see <a href="perluniintro.html">perluniintro</a>.</p>
</li>
<li><a name="mbstowcs"></a><b><code class="inline"><span class="w">mbstowcs</span></code>
</b>
<p>This is identical to the C function <code class="inline"><span class="i">mbstowcs</span><span class="s">(</span><span class="s">)</span></code>
.</p>
<p>See <a href="#mblen">mblen</a>.</p>
</li>
<li><a name="mbtowc"></a><b><code class="inline"><span class="w">mbtowc</span></code>
</b>
<p>This is identical to the C function <code class="inline"><span class="i">mbtowc</span><span class="s">(</span><span class="s">)</span></code>
.</p>
<p>See <a href="#mblen">mblen</a>.</p>
</li>
<li><a name="memchr"></a><b><code class="inline"><span class="w">memchr</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">memchr</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific, see <a href="functions/index.html">index</a> instead.</p>
</li>
<li><a name="memcmp"></a><b><code class="inline"><span class="w">memcmp</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">memcmp</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific, use <code class="inline">eq</code>
 instead, see <a href="perlop.html">perlop</a>.</p>
</li>
<li><a name="memcpy"></a><b><code class="inline"><span class="w">memcpy</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">memcpy</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific, use <code class="inline">=</code>
, see <a href="perlop.html">perlop</a>, or see <a href="functions/substr.html">substr</a>.</p>
</li>
<li><a name="memmove"></a><b><code class="inline"><span class="w">memmove</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">memmove</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific, use <code class="inline">=</code>
, see <a href="perlop.html">perlop</a>, or see <a href="functions/substr.html">substr</a>.</p>
</li>
<li><a name="memset"></a><b><code class="inline"><span class="w">memset</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">memset</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific, use <code class="inline"><span class="w">x</span></code>
 instead, see <a href="perlop.html">perlop</a>.</p>
</li>
<li><a name="mkdir"></a><b><code class="inline"><a class="l_k" href="functions/mkdir.html">mkdir</a></code></b>
<p>This is identical to Perl's builtin <code class="inline"><a class="l_k" href="functions/mkdir.html">mkdir()</a></code> function
for creating directories, see <a href="functions/mkdir.html">mkdir</a>.</p>
</li>
<li><a name="mkfifo"></a><b><code class="inline"><span class="w">mkfifo</span></code>
</b>
<p>This is similar to the C function <code class="inline"><span class="i">mkfifo</span><span class="s">(</span><span class="s">)</span></code>
 for creating
FIFO special files.</p>
<pre class="verbatim"><ol><li>	if (mkfifo($path, $mode)) { ....</li></ol></pre><p>Returns <code class="inline"><a class="l_k" href="functions/undef.html">undef</a></code> on failure.  The <code class="inline"><span class="i">$mode</span></code>
 is similar to the
mode of <code class="inline"><a class="l_k" href="functions/mkdir.html">mkdir()</a></code>, see <a href="functions/mkdir.html">mkdir</a>, though for <code class="inline"><span class="w">mkfifo</span></code>

you <b>must</b> specify the <code class="inline"><span class="i">$mode</span></code>
.</p>
</li>
<li><a name="mktime"></a><b><code class="inline"><span class="w">mktime</span></code>
</b>
<p>Convert date/time info to a calendar time.</p>
<p>Synopsis:</p>
<pre class="verbatim"><ol><li>	<span class="i">mktime</span><span class="s">(</span><span class="w">sec</span><span class="cm">,</span> <span class="w">min</span><span class="cm">,</span> <span class="w">hour</span><span class="cm">,</span> <span class="w">mday</span><span class="cm">,</span> <span class="w">mon</span><span class="cm">,</span> <span class="w">year</span><span class="cm">,</span> <span class="w">wday</span> = <span class="n">0</span><span class="cm">,</span></li><li>	       <span class="w">yday</span> = <span class="n">0</span><span class="cm">,</span> <span class="w">isdst</span> = <span class="n">-1</span><span class="s">)</span></li></ol></pre><p>The month (<code class="inline"><span class="w">mon</span></code>
), weekday (<code class="inline"><span class="w">wday</span></code>
), and yearday (<code class="inline"><span class="w">yday</span></code>
) begin at zero,
<i>i.e.</i>, January is 0, not 1; Sunday is 0, not 1; January 1st is 0, not 1.  The
year (<code class="inline"><span class="w">year</span></code>
) is given in years since 1900; <i>i.e.</i>, the year 1995 is 95; the
year 2001 is 101.  Consult your system's <code class="inline"><span class="i">mktime</span><span class="s">(</span><span class="s">)</span></code>
 manpage for details
about these and the other arguments.</p>
<p>Calendar time for December 12, 1995, at 10:30 am.</p>
<pre class="verbatim"><ol><li>	<span class="i">$time_t</span> = <span class="i">POSIX::mktime</span><span class="s">(</span> <span class="n">0</span><span class="cm">,</span> <span class="n">30</span><span class="cm">,</span> <span class="n">10</span><span class="cm">,</span> <span class="n">12</span><span class="cm">,</span> <span class="n">11</span><span class="cm">,</span> <span class="n">95</span> <span class="s">)</span><span class="sc">;</span></li><li>	<a class="l_k" href="functions/print.html">print</a> <span class="q">&quot;Date = &quot;</span><span class="cm">,</span> <span class="i">POSIX::ctime</span><span class="s">(</span><span class="i">$time_t</span><span class="s">)</span><span class="sc">;</span></li></ol></pre><p>Returns <code class="inline"><a class="l_k" href="functions/undef.html">undef</a></code> on failure.</p>
</li>
<li><a name="modf"></a><b><code class="inline"><span class="w">modf</span></code>
</b>
<p>Return the integral and fractional parts of a floating-point number.</p>
<pre class="verbatim"><ol><li>	<span class="s">(</span><span class="i">$fractional</span><span class="cm">,</span> <span class="i">$integral</span><span class="s">)</span> = <span class="i">POSIX::modf</span><span class="s">(</span> <span class="n">3.14</span> <span class="s">)</span><span class="sc">;</span></li></ol></pre><p>See also <a href="#round">round</a>.</p>
</li>
<li><a name="NaN"></a><b><code class="inline"><span class="w">NaN</span></code>
</b>
<p>The not-a-number as a constant:</p>
<pre class="verbatim"><ol><li>   <a class="l_k" href="functions/use.html">use</a> <span class="w">POSIX</span> <span class="q">qw(NaN)</span><span class="sc">;</span></li><li>   <a class="l_k" href="functions/my.html">my</a> <span class="i">$nan</span> = <span class="w">NaN</span><span class="sc">;</span></li></ol></pre><p>See also <a href="#nan">nan</a>, <code class="inline"><span class="q">/isnan</span></code>
, and <a href="#fpclassify">fpclassify</a>.</p>
</li>
<li><a name="nan"></a><b><code class="inline"><span class="w">nan</span></code>
</b>
<pre class="verbatim"><ol><li>   <a class="l_k" href="functions/my.html">my</a> <span class="i">$nan</span> = <span class="i">nan</span><span class="s">(</span><span class="s">)</span><span class="sc">;</span></li></ol></pre><p>Returns <code class="inline"><span class="w">NaN</span></code>
, not-a-number [C99].</p>
<p>The returned NaN is always a <i>quiet</i> NaN, as opposed to <i>signaling</i>.</p>
<p>With an argument, can be used to generate a NaN with <i>payload</i>.
The argument is first interpreted as a floating point number,
but then any fractional parts are truncated (towards zero),
and the value is interpreted as an unsigned integer.
The bits of this integer are stored in the unused bits of the NaN.</p>
<p>The result has a dual nature: it is a NaN, but it also carries
the integer inside it.  The integer can be retrieved with <a href="#getpayload">getpayload</a>.
Note, though, that the payload is not propagated, not even on copies,
and definitely not in arithmetic operations.</p>
<p>How many bits fit in the NaN depends on what kind of floating points
are being used, but on the most common platforms (64-bit IEEE 754,
or the x86 80-bit long doubles) there are 51 and 61 bits available,
respectively.  (There would be 52 and 62, but the quiet/signaling
bit of NaNs takes away one.)  However, because of the floating-point-to-
integer-and-back conversions, please test carefully whether you get back
what you put in.  If your integers are only 32 bits wide, you probably
should not rely on more than 32 bits of payload.</p>
<p>Whether a "signaling" NaN is in any way different from a "quiet" NaN,
depends on the platform.  Also note that the payload of the default
NaN (no argument to nan()) is not necessarily zero, use <code class="inline"><span class="w">setpayload</span></code>

to explicitly set the payload.  On some platforms like the 32-bit x86,
(unless using the 80-bit long doubles) the signaling bit is not supported
at all.</p>
<p>See also <a href="#isnan">isnan</a>, <a href="#NaN">NaN</a>, <a href="#setpayload">setpayload</a> and <a href="#issignaling">issignaling</a>.</p>
</li>
<li><a name="nearbyint"></a><b><code class="inline"><span class="w">nearbyint</span></code>
</b>
<p>Returns the nearest integer to the argument, according to the current
rounding mode (see <a href="#fegetround">fegetround</a>) [C99].</p>
</li>
<li><a name="nextafter"></a><b><code class="inline"><span class="w">nextafter</span></code>
</b>
<p>Returns the next representable floating point number after <code class="inline"><span class="w">x</span></code>
 in the
direction of <code class="inline"><a class="l_k" href="functions/y.html">y</a></code> [C99].</p>
<pre class="verbatim"><ol><li> <a class="l_k" href="functions/my.html">my</a> <span class="i">$nextafter</span> = <span class="i">POSIX::nextafter</span><span class="s">(</span><span class="i">$x</span><span class="cm">,</span> <span class="i">$y</span><span class="s">)</span><span class="sc">;</span></li></ol></pre><p>Like <a href="#nexttoward">nexttoward</a>, but potentially less accurate.</p>
</li>
<li><a name="nexttoward"></a><b><code class="inline"><span class="w">nexttoward</span></code>
</b>
<p>Returns the next representable floating point number after <code class="inline"><span class="w">x</span></code>
 in the
direction of <code class="inline"><a class="l_k" href="functions/y.html">y</a></code> [C99].</p>
<pre class="verbatim"><ol><li> <a class="l_k" href="functions/my.html">my</a> <span class="i">$nexttoward</span> = <span class="i">POSIX::nexttoward</span><span class="s">(</span><span class="i">$x</span><span class="cm">,</span> <span class="i">$y</span><span class="s">)</span><span class="sc">;</span></li></ol></pre><p>Like <a href="#nextafter">nextafter</a>, but potentially more accurate.</p>
</li>
<li><a name="nice"></a><b><code class="inline"><span class="w">nice</span></code>
</b>
<p>This is similar to the C function <code class="inline"><span class="i">nice</span><span class="s">(</span><span class="s">)</span></code>
, for changing
the scheduling preference of the current process.  Positive
arguments mean a more polite process, negative values a more
needy process.  Normal (non-root) user processes can only change towards
being more polite.</p>
<p>Returns <code class="inline"><a class="l_k" href="functions/undef.html">undef</a></code> on failure.</p>
</li>
<li><a name="offsetof"></a><b><code class="inline"><span class="w">offsetof</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">offsetof</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific, you probably want to see <a href="functions/pack.html">pack</a> instead.</p>
</li>
<li><a name="open"></a><b><code class="inline"><a class="l_k" href="functions/open.html">open</a></code></b>
<p>Open a file for reading for writing.  This returns file descriptors, not
Perl filehandles.  Use <code class="inline"><span class="w">POSIX::close</span></code>
 to close the file.</p>
<p>Open a file read-only with mode 0666.</p>
<pre class="verbatim"><ol><li>	<span class="i">$fd</span> = <span class="i">POSIX::open</span><span class="s">(</span> <span class="q">&quot;foo&quot;</span> <span class="s">)</span><span class="sc">;</span></li></ol></pre><p>Open a file for read and write.</p>
<pre class="verbatim"><ol><li>	<span class="i">$fd</span> = <span class="i">POSIX::open</span><span class="s">(</span> <span class="q">&quot;foo&quot;</span><span class="cm">,</span> <span class="i">&amp;POSIX::O_RDWR</span> <span class="s">)</span><span class="sc">;</span></li></ol></pre><p>Open a file for write, with truncation.</p>
<pre class="verbatim"><ol><li>	<span class="i">$fd</span> = <span class="i">POSIX::open</span><span class="s">(</span></li><li>		<span class="q">&quot;foo&quot;</span><span class="cm">,</span> <span class="i">&amp;POSIX::O_WRONLY</span> | <span class="i">&amp;POSIX::O_TRUNC</span></li><li>	<span class="s">)</span><span class="sc">;</span></li></ol></pre><p>Create a new file with mode 0640.  Set up the file for writing.</p>
<pre class="verbatim"><ol><li>	<span class="i">$fd</span> = <span class="i">POSIX::open</span><span class="s">(</span></li><li>		<span class="q">&quot;foo&quot;</span><span class="cm">,</span> <span class="i">&amp;POSIX::O_CREAT</span> | <span class="i">&amp;POSIX::O_WRONLY</span><span class="cm">,</span> <span class="n">0640</span></li><li>	<span class="s">)</span><span class="sc">;</span></li></ol></pre><p>Returns <code class="inline"><a class="l_k" href="functions/undef.html">undef</a></code> on failure.</p>
<p>See also <a href="functions/sysopen.html">sysopen</a>.</p>
</li>
<li><a name="opendir"></a><b><code class="inline"><a class="l_k" href="functions/opendir.html">opendir</a></code></b>
<p>Open a directory for reading.</p>
<pre class="verbatim"><ol><li>	<span class="i">$dir</span> = <span class="i">POSIX::opendir</span><span class="s">(</span> <span class="q">&quot;/var&quot;</span> <span class="s">)</span><span class="sc">;</span></li><li>	<span class="i">@files</span> = <span class="i">POSIX::readdir</span><span class="s">(</span> <span class="i">$dir</span> <span class="s">)</span><span class="sc">;</span></li><li>	<span class="i">POSIX::closedir</span><span class="s">(</span> <span class="i">$dir</span> <span class="s">)</span><span class="sc">;</span></li></ol></pre><p>Returns <code class="inline"><a class="l_k" href="functions/undef.html">undef</a></code> on failure.</p>
</li>
<li><a name="pathconf"></a><b><code class="inline"><span class="w">pathconf</span></code>
</b>
<p>Retrieves the value of a configurable limit on a file or directory.</p>
<p>The following will determine the maximum length of the longest allowable
pathname on the filesystem which holds <code class="inline">/var</code>.</p>
<pre class="verbatim"><ol><li>	<span class="i">$path_max</span> = <span class="i">POSIX::pathconf</span><span class="s">(</span> <span class="q">&quot;/var&quot;</span><span class="cm">,</span></li><li>				      <span class="i">&amp;POSIX::_PC_PATH_MAX</span> <span class="s">)</span><span class="sc">;</span></li></ol></pre><p>Returns <code class="inline"><a class="l_k" href="functions/undef.html">undef</a></code> on failure.</p>
</li>
<li><a name="pause"></a><b><code class="inline"><span class="w">pause</span></code>
</b>
<p>This is similar to the C function <code class="inline"><span class="i">pause</span><span class="s">(</span><span class="s">)</span></code>
, which suspends
the execution of the current process until a signal is received.</p>
<p>Returns <code class="inline"><a class="l_k" href="functions/undef.html">undef</a></code> on failure.</p>
</li>
<li><a name="perror"></a><b><code class="inline"><span class="w">perror</span></code>
</b>
<p>This is identical to the C function <code class="inline"><span class="i">perror</span><span class="s">(</span><span class="s">)</span></code>
, which outputs to the
standard error stream the specified message followed by <code class="inline"><span class="q">&quot;: &quot;</span></code>
 and the
current error string.  Use the <code class="inline"><a class="l_k" href="functions/warn.html">warn()</a></code> function and the <code class="inline"><span class="i">$!</span></code>

variable instead, see <a href="functions/warn.html">warn</a> and <a href="perlvar.html#%24ERRNO">$ERRNO in perlvar</a>.</p>
</li>
<li><a name="pipe"></a><b><code class="inline"><a class="l_k" href="functions/pipe.html">pipe</a></code></b>
<p>Create an interprocess channel.  This returns file descriptors like those
returned by <code class="inline"><span class="w">POSIX::open</span></code>
.</p>
<pre class="verbatim"><ol><li>	<a class="l_k" href="functions/my.html">my</a> <span class="s">(</span><span class="i">$read</span><span class="cm">,</span> <span class="i">$write</span><span class="s">)</span> = <span class="i">POSIX::pipe</span><span class="s">(</span><span class="s">)</span><span class="sc">;</span></li><li>	<span class="i">POSIX::write</span><span class="s">(</span> <span class="i">$write</span><span class="cm">,</span> <span class="q">&quot;hello&quot;</span><span class="cm">,</span> <span class="n">5</span> <span class="s">)</span><span class="sc">;</span></li><li>	<span class="i">POSIX::read</span><span class="s">(</span> <span class="i">$read</span><span class="cm">,</span> <span class="i">$buf</span><span class="cm">,</span> <span class="n">5</span> <span class="s">)</span><span class="sc">;</span></li></ol></pre><p>See also <a href="functions/pipe.html">pipe</a>.</p>
</li>
<li><a name="pow"></a><b><code class="inline"><span class="w">pow</span></code>
</b>
<p>Computes <code class="inline"><span class="i">$x</span></code>
 raised to the power <code class="inline"><span class="i">$exponent</span></code>
.</p>
<pre class="verbatim"><ol><li>	<span class="i">$ret</span> = <span class="i">POSIX::pow</span><span class="s">(</span> <span class="i">$x</span><span class="cm">,</span> <span class="i">$exponent</span> <span class="s">)</span><span class="sc">;</span></li></ol></pre><p>You can also use the <code class="inline"><span class="i">**</span></code>
 operator, see <a href="perlop.html">perlop</a>.</p>
</li>
<li><a name="printf"></a><b><code class="inline"><a class="l_k" href="functions/printf.html">printf</a></code></b>
<p>Formats and prints the specified arguments to <code class="inline"><span class="w">STDOUT</span></code>
.
See also <a href="functions/printf.html">printf</a>.</p>
</li>
<li><a name="putc"></a><b><code class="inline"><span class="w">putc</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">putc</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific, see <a href="functions/print.html">print</a> instead.</p>
</li>
<li><a name="putchar"></a><b><code class="inline"><span class="w">putchar</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">putchar</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific, see <a href="functions/print.html">print</a> instead.</p>
</li>
<li><a name="puts"></a><b><code class="inline"><span class="w">puts</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">puts</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific, see <a href="functions/print.html">print</a> instead.</p>
</li>
<li><a name="qsort"></a><b><code class="inline"><span class="w">qsort</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">qsort</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific, see <a href="functions/sort.html">sort</a> instead.</p>
</li>
<li><a name="raise"></a><b><code class="inline"><span class="w">raise</span></code>
</b>
<p>Sends the specified signal to the current process.
See also <a href="functions/kill.html">kill</a> and the <code class="inline"><span class="i">$$</span></code>
 in <a href="perlvar.html#%24PID">$PID in perlvar</a>.</p>
</li>
<li><a name="rand"></a><b><code class="inline"><a class="l_k" href="functions/rand.html">rand</a></code></b>
<p>Not implemented.  <code class="inline"><a class="l_k" href="functions/rand.html">rand()</a></code> is non-portable, see <a href="functions/rand.html">rand</a> instead.</p>
</li>
<li><a name="read"></a><b><code class="inline"><a class="l_k" href="functions/read.html">read</a></code></b>
<p>Read from a file.  This uses file descriptors such as those obtained by
calling <code class="inline"><span class="w">POSIX::open</span></code>
.  If the buffer <code class="inline"><span class="i">$buf</span></code>
 is not large enough for the
read then Perl will extend it to make room for the request.</p>
<pre class="verbatim"><ol><li>	<span class="i">$fd</span> = <span class="i">POSIX::open</span><span class="s">(</span> <span class="q">&quot;foo&quot;</span><span class="cm">,</span> <span class="i">&amp;POSIX::O_RDONLY</span> <span class="s">)</span><span class="sc">;</span></li><li>	<span class="i">$bytes</span> = <span class="i">POSIX::read</span><span class="s">(</span> <span class="i">$fd</span><span class="cm">,</span> <span class="i">$buf</span><span class="cm">,</span> <span class="n">3</span> <span class="s">)</span><span class="sc">;</span></li></ol></pre><p>Returns <code class="inline"><a class="l_k" href="functions/undef.html">undef</a></code> on failure.</p>
<p>See also <a href="functions/sysread.html">sysread</a>.</p>
</li>
<li><a name="readdir"></a><b><code class="inline"><a class="l_k" href="functions/readdir.html">readdir</a></code></b>
<p>This is identical to Perl's builtin <code class="inline"><a class="l_k" href="functions/readdir.html">readdir()</a></code> function
for reading directory entries, see <a href="functions/readdir.html">readdir</a>.</p>
</li>
<li><a name="realloc"></a><b><code class="inline"><span class="w">realloc</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">realloc</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific.  Perl does memory management transparently.</p>
</li>
<li><a name="remainder"></a><b><code class="inline"><span class="w">remainder</span></code>
</b>
<p>Given <code class="inline"><span class="w">x</span></code>
 and <code class="inline"><a class="l_k" href="functions/y.html">y</a></code>, returns the value <code class="inline"><span class="w">x</span> - <span class="w">n</span>*<span class="q">y</span></code>
, where <code class="inline"><span class="w">n</span></code>
 is the integer
closest to <code class="inline"><span class="w">x</span></code>
/<code class="inline"><a class="l_k" href="functions/y.html">y</a></code>. [C99]</p>
<pre class="verbatim"><ol><li> <a class="l_k" href="functions/my.html">my</a> <span class="i">$remainder</span> = <span class="i">POSIX::remainder</span><span class="s">(</span><span class="i">$x</span><span class="cm">,</span> <span class="i">$y</span><span class="s">)</span></li></ol></pre><p>See also <a href="#remquo">remquo</a>.</p>
</li>
<li><a name="remove"></a><b><code class="inline"><span class="w">remove</span></code>
</b>
<p>This is identical to Perl's builtin <code class="inline"><a class="l_k" href="functions/unlink.html">unlink()</a></code> function
for removing files, see <a href="functions/unlink.html">unlink</a>.</p>
</li>
<li><a name="remquo"></a><b><code class="inline"><span class="w">remquo</span></code>
</b>
<p>Like <a href="#remainder">remainder</a> but also returns the low-order bits of the quotient (n)
[C99]</p>
<p>(This is quite esoteric interface, mainly used to implement numerical
algorithms.)</p>
</li>
<li><a name="rename"></a><b><code class="inline"><a class="l_k" href="functions/rename.html">rename</a></code></b>
<p>This is identical to Perl's builtin <code class="inline"><a class="l_k" href="functions/rename.html">rename()</a></code> function
for renaming files, see <a href="functions/rename.html">rename</a>.</p>
</li>
<li><a name="rewind"></a><b><code class="inline"><span class="w">rewind</span></code>
</b>
<p>Seeks to the beginning of the file.</p>
</li>
<li><a name="rewinddir"></a><b><code class="inline"><a class="l_k" href="functions/rewinddir.html">rewinddir</a></code></b>
<p>This is identical to Perl's builtin <code class="inline"><a class="l_k" href="functions/rewinddir.html">rewinddir()</a></code> function for
rewinding directory entry streams, see <a href="functions/rewinddir.html">rewinddir</a>.</p>
</li>
<li><a name="rint"></a><b><code class="inline"><span class="w">rint</span></code>
</b>
<p>Identical to <a href="#lrint">lrint</a>.</p>
</li>
<li><a name="rmdir"></a><b><code class="inline"><a class="l_k" href="functions/rmdir.html">rmdir</a></code></b>
<p>This is identical to Perl's builtin <code class="inline"><a class="l_k" href="functions/rmdir.html">rmdir()</a></code> function
for removing (empty) directories, see <a href="functions/rmdir.html">rmdir</a>.</p>
</li>
<li><a name="round"></a><b><code class="inline"><span class="w">round</span></code>
</b>
<p>Returns the integer (but still as floating point) nearest to the
argument [C99].</p>
<p>See also <a href="#ceil">ceil</a>, <a href="#floor">floor</a>, <a href="#lround">lround</a>, <a href="#modf">modf</a>, and <a href="#trunc">trunc</a>.</p>
</li>
<li><a name="scalbn"></a><b><code class="inline"><span class="w">scalbn</span></code>
</b>
<p>Returns <code class="inline"><span class="w">x</span> * <span class="n">2</span>**<span class="q">y</span></code>
 [C99].</p>
<p>See also <a href="#frexp">frexp</a> and <a href="#ldexp">ldexp</a>.</p>
</li>
<li><a name="scanf"></a><b><code class="inline"><span class="w">scanf</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">scanf</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific, use &lt;&gt; and regular expressions instead,
see <a href="perlre.html">perlre</a>.</p>
</li>
<li><a name="setgid"></a><b><code class="inline"><span class="w">setgid</span></code>
</b>
<p>Sets the real group identifier and the effective group identifier for
this process.  Similar to assigning a value to the Perl's builtin
<code class="inline"><span class="i">$)</span></code>
 variable, see <a href="perlvar.html#%24EGID">$EGID in perlvar</a>, except that the latter
will change only the real user identifier, and that the setgid()
uses only a single numeric argument, as opposed to a space-separated
list of numbers.</p>
</li>
<li><a name="setjmp"></a><b><code class="inline"><span class="w">setjmp</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">setjmp</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific: use <code class="inline"><a class="l_k" href="functions/eval.html">eval</a> <span class="s">{</span><span class="s">}</span></code>
 instead,
see <a href="functions/eval.html">eval</a>.</p>
</li>
<li><a name="setlocale"></a><b><code class="inline"><span class="w">setlocale</span></code>
</b>
<p>WARNING!  Do NOT use this function in a <a href="threads.html">thread</a>.  The locale
will change in all other threads at the same time, and should your
thread get paused by the operating system, and another started, that
thread will not have the locale it is expecting.  On some platforms,
there can be a race leading to segfaults if two threads call this
function nearly simultaneously.</p>
<p>Modifies and queries the program's underlying locale.  Users of this
function should read <a href="perllocale.html">perllocale</a>, whch provides a comprehensive
discussion of Perl locale handling, knowledge of which is necessary to
properly use this function.  It contains
<a href="perllocale.html#The-setlocale-function">a section devoted to this function</a>.
The discussion here is merely a summary reference for <code class="inline"><span class="i">setlocale</span><span class="s">(</span><span class="s">)</span></code>
.
Note that Perl itself is almost entirely unaffected by the locale
except within the scope of <code class="inline"><span class="q">&quot;use locale&quot;</span></code>
.  (Exceptions are listed
in <a href="perllocale.html#Not-within-the-scope-of-%22use-locale%22">Not within the scope of use locale in perllocale</a>.)</p>
<p>The following examples assume</p>
<pre class="verbatim"><ol><li>	<a class="l_k" href="functions/use.html">use</a> <span class="w">POSIX</span> <span class="q">qw(setlocale LC_ALL LC_CTYPE)</span><span class="sc">;</span></li></ol></pre><p>has been issued.</p>
<p>The following will set the traditional UNIX system locale behavior
(the second argument <code class="inline"><span class="q">&quot;C&quot;</span></code>
).</p>
<pre class="verbatim"><ol><li>	<span class="i">$loc</span> = <span class="i">setlocale</span><span class="s">(</span> <span class="w">LC_ALL</span><span class="cm">,</span> <span class="q">&quot;C&quot;</span> <span class="s">)</span><span class="sc">;</span></li></ol></pre><p>The following will query the current <code class="inline"><span class="w">LC_CTYPE</span></code>
 category.  (No second
argument means 'query'.)</p>
<pre class="verbatim"><ol><li>	<span class="i">$loc</span> = <span class="i">setlocale</span><span class="s">(</span> <span class="w">LC_CTYPE</span> <span class="s">)</span><span class="sc">;</span></li></ol></pre><p>The following will set the <code class="inline"><span class="w">LC_CTYPE</span></code>
 behaviour according to the locale
environment variables (the second argument <code class="inline"><span class="q">&quot;&quot;</span></code>
).
Please see your system's <code class="inline"><span class="i">setlocale</span><span class="s">(</span><span class="n">3</span><span class="s">)</span></code>
 documentation for the locale
environment variables' meaning or consult <a href="perllocale.html">perllocale</a>.</p>
<pre class="verbatim"><ol><li>	<span class="i">$loc</span> = <span class="i">setlocale</span><span class="s">(</span> <span class="w">LC_CTYPE</span><span class="cm">,</span> <span class="q">&quot;&quot;</span> <span class="s">)</span><span class="sc">;</span></li></ol></pre><p>The following will set the <code class="inline"><span class="w">LC_COLLATE</span></code>
 behaviour to Argentinian
Spanish. <b>NOTE</b>: The naming and availability of locales depends on
your operating system. Please consult <a href="perllocale.html">perllocale</a> for how to find
out which locales are available in your system.</p>
<pre class="verbatim"><ol><li>	<span class="i">$loc</span> = <span class="i">setlocale</span><span class="s">(</span> <span class="w">LC_COLLATE</span><span class="cm">,</span> <span class="q">&quot;es_AR.ISO8859-1&quot;</span> <span class="s">)</span><span class="sc">;</span></li></ol></pre></li>
<li><a name="setpayload"></a><b><code class="inline"><span class="w">setpayload</span></code>
</b>
<pre class="verbatim"><ol><li>	<a class="l_k" href="functions/use.html">use</a> <span class="w">POSIX</span> <span class="q">&#39;:nan_payload&#39;</span><span class="sc">;</span></li><li>	<span class="i">setpayload</span><span class="s">(</span><span class="i">$var</span><span class="cm">,</span> <span class="i">$payload</span><span class="s">)</span><span class="sc">;</span></li></ol></pre><p>Sets the <code class="inline"><span class="w">NaN</span></code>
 payload of var.</p>
<p>NOTE: the NaN payload APIs are based on the latest (as of June 2015)
proposed ISO C interfaces, but they are not yet a standard.  Things
may change.</p>
<p>See <a href="#nan">nan</a> for more discussion about <code class="inline"><span class="w">NaN</span></code>
.</p>
<p>See also <a href="#setpayloadsig">setpayloadsig</a>, <a href="#isnan">isnan</a>, <a href="#getpayload">getpayload</a>, and <a href="#issignaling">issignaling</a>.</p>
</li>
<li><a name="setpayloadsig"></a><b><code class="inline"><span class="w">setpayloadsig</span></code>
</b>
<pre class="verbatim"><ol><li>	<a class="l_k" href="functions/use.html">use</a> <span class="w">POSIX</span> <span class="q">&#39;:nan_payload&#39;</span><span class="sc">;</span></li><li>	<span class="i">setpayloadsig</span><span class="s">(</span><span class="i">$var</span><span class="cm">,</span> <span class="i">$payload</span><span class="s">)</span><span class="sc">;</span></li></ol></pre><p>Like <a href="#setpayload">setpayload</a> but also makes the NaN <i>signaling</i>.</p>
<p>Depending on the platform the NaN may or may not behave differently.</p>
<p>Note the API instability warning in <a href="#setpayload">setpayload</a>.</p>
<p>Note that because how the floating point formats work out, on the most
common platforms signaling payload of zero is best avoided,
since it might end up being identical to <code class="inline">+<span class="w">Inf</span></code>
.</p>
<p>See also <a href="#nan">nan</a>, <a href="#isnan">isnan</a>, <a href="#getpayload">getpayload</a>, and <a href="#issignaling">issignaling</a>.</p>
</li>
<li><a name="setpgid"></a><b><code class="inline"><span class="w">setpgid</span></code>
</b>
<p>This is similar to the C function <code class="inline"><span class="i">setpgid</span><span class="s">(</span><span class="s">)</span></code>
 for
setting the process group identifier of the current process.</p>
<p>Returns <code class="inline"><a class="l_k" href="functions/undef.html">undef</a></code> on failure.</p>
</li>
<li><a name="setsid"></a><b><code class="inline"><span class="w">setsid</span></code>
</b>
<p>This is identical to the C function <code class="inline"><span class="i">setsid</span><span class="s">(</span><span class="s">)</span></code>
 for
setting the session identifier of the current process.</p>
</li>
<li><a name="setuid"></a><b><code class="inline"><span class="w">setuid</span></code>
</b>
<p>Sets the real user identifier and the effective user identifier for
this process.  Similar to assigning a value to the Perl's builtin
<code class="inline"><span class="i">$&lt;</span></code>
 variable, see <a href="perlvar.html#%24UID">$UID in perlvar</a>, except that the latter
will change only the real user identifier.</p>
</li>
<li><a name="sigaction"></a><b><code class="inline"><span class="w">sigaction</span></code>
</b>
<p>Detailed signal management.  This uses <code class="inline"><span class="w">POSIX::SigAction</span></code>
 objects for
the <code class="inline"><span class="w">action</span></code>
 and <code class="inline"><span class="w">oldaction</span></code>
 arguments (the oldaction can also be
just a hash reference).  Consult your system's <code class="inline"><span class="w">sigaction</span></code>
 manpage
for details, see also <code class="inline"><span class="w">POSIX::SigRt</span></code>
.</p>
<p>Synopsis:</p>
<pre class="verbatim"><ol><li>	<span class="i">sigaction</span><span class="s">(</span><span class="w">signal</span><span class="cm">,</span> <span class="w">action</span><span class="cm">,</span> <span class="w">oldaction</span> = <span class="n">0</span><span class="s">)</span></li></ol></pre><p>Returns <code class="inline"><a class="l_k" href="functions/undef.html">undef</a></code> on failure.  The <code class="inline"><span class="w">signal</span></code>
 must be a number (like
<code class="inline"><span class="w">SIGHUP</span></code>
), not a string (like <code class="inline"><span class="q">&quot;SIGHUP&quot;</span></code>
), though Perl does try hard
to understand you.</p>
<p>If you use the <code class="inline"><span class="w">SA_SIGINFO</span></code>
 flag, the signal handler will in addition to
the first argument, the signal name, also receive a second argument, a
hash reference, inside which are the following keys with the following
semantics, as defined by POSIX/SUSv3:</p>
<pre class="verbatim"><ol><li>    <span class="w">signo</span>       <span class="w">the</span> <span class="w">signal</span> <span class="w">number</span></li><li>    <span class="w">errno</span>       <span class="w">the</span> <span class="w">error</span> <span class="w">number</span></li><li>    <span class="w">code</span>        if <span class="w">this</span> <span class="w">is</span> <span class="w">zero</span> or <span class="w">less</span><span class="cm">,</span> <span class="w">the</span> <span class="w">signal</span> <span class="w">was</span> <span class="w">sent</span> <span class="w">by</span></li><li>                <span class="w">a</span> <span class="w">user</span> <span class="w">process</span> and <span class="w">the</span> <span class="w">uid</span> and <span class="w">pid</span> <span class="w">make</span> <span class="w">sense</span><span class="cm">,</span></li><li>                <span class="w">otherwise</span> <span class="w">the</span> <span class="w">signal</span> <span class="w">was</span> <span class="w">sent</span> <span class="w">by</span> <span class="w">the</span> <span class="w">kernel</span></li></ol></pre><p>The constants for specific <code class="inline"><span class="w">code</span></code>
 values can be imported individually
or using the <code class="inline"><span class="j">:</span><span class="w">signal_h_si_code</span></code>
 tag.</p>
<p>The following are also defined by POSIX/SUSv3, but unfortunately
not very widely implemented:</p>
<pre class="verbatim"><ol><li>    <span class="w">pid</span>         <span class="w">the</span> <span class="w">process</span> <span class="w">id</span> <span class="w">generating</span> <span class="w">the</span> <span class="w">signal</span></li><li>    <span class="w">uid</span>         <span class="w">the</span> <span class="w">uid</span> <span class="w">of</span> <span class="w">the</span> <span class="w">process</span> <span class="w">id</span> <span class="w">generating</span> <span class="w">the</span> <span class="w">signal</span></li><li>    <span class="w">status</span>      <a class="l_k" href="functions/exit.html">exit</a> <span class="w">value</span> <a class="l_k" href="functions/or.html">or</a> <span class="w">signal</span> <a class="l_k" href="functions/for.html">for</a> <span class="w">SIGCHLD</span></li><li>    <span class="w">band</span>        <span class="w">band</span> <span class="w">event</span> <a class="l_k" href="functions/for.html">for</a> <span class="w">SIGPOLL</span></li><li>    <span class="w">addr</span>        <span class="w">address</span> <span class="w">of</span> <span class="w">faulting</span> <span class="w">instruction</span> <a class="l_k" href="functions/or.html">or</a> <span class="w">memory</span></li><li>                <span class="w">reference</span> <a class="l_k" href="functions/for.html">for</a> <span class="w">SIGILL</span><span class="cm">,</span> <span class="w">SIGFPE</span><span class="cm">,</span> <span class="w">SIGSEGV</span> <a class="l_k" href="functions/or.html">or</a> <span class="w">SIGBUS</span></li></ol></pre><p>A third argument is also passed to the handler, which contains a copy
of the raw binary contents of the <code class="inline"><span class="w">siginfo</span></code>
 structure: if a system has
some non-POSIX fields, this third argument is where to <code class="inline"><a class="l_k" href="functions/unpack.html">unpack()</a></code> them
from.</p>
<p>Note that not all <code class="inline"><span class="w">siginfo</span></code>
 values make sense simultaneously (some are
valid only for certain signals, for example), and not all values make
sense from Perl perspective, you should to consult your system's
<code class="inline"><span class="w">sigaction</span></code>
 and possibly also <code class="inline"><span class="w">siginfo</span></code>
 documentation.</p>
</li>
<li><a name="siglongjmp"></a><b><code class="inline"><span class="w">siglongjmp</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">siglongjmp</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific: use <a href="functions/die.html">die</a> instead.</p>
</li>
<li><a name="signbit"></a><b><code class="inline"><span class="w">signbit</span></code>
</b>
<p>Returns zero for positive arguments, non-zero for negative arguments [C99].</p>
</li>
<li><a name="sigpending"></a><b><code class="inline"><span class="w">sigpending</span></code>
</b>
<p>Examine signals that are blocked and pending.  This uses <code class="inline"><span class="w">POSIX::SigSet</span></code>

objects for the <code class="inline"><span class="w">sigset</span></code>
 argument.  Consult your system's <code class="inline"><span class="w">sigpending</span></code>

manpage for details.</p>
<p>Synopsis:</p>
<pre class="verbatim"><ol><li>	<span class="i">sigpending</span><span class="s">(</span><span class="w">sigset</span><span class="s">)</span></li></ol></pre><p>Returns <code class="inline"><a class="l_k" href="functions/undef.html">undef</a></code> on failure.</p>
</li>
<li><a name="sigprocmask"></a><b><code class="inline"><span class="w">sigprocmask</span></code>
</b>
<p>Change and/or examine calling process's signal mask.  This uses
<code class="inline"><span class="w">POSIX::SigSet</span></code>
 objects for the <code class="inline"><span class="w">sigset</span></code>
 and <code class="inline"><span class="w">oldsigset</span></code>
 arguments.
Consult your system's <code class="inline"><span class="w">sigprocmask</span></code>
 manpage for details.</p>
<p>Synopsis:</p>
<pre class="verbatim"><ol><li>	<span class="i">sigprocmask</span><span class="s">(</span><span class="w">how</span><span class="cm">,</span> <span class="w">sigset</span><span class="cm">,</span> <span class="w">oldsigset</span> = <span class="n">0</span><span class="s">)</span></li></ol></pre><p>Returns <code class="inline"><a class="l_k" href="functions/undef.html">undef</a></code> on failure.</p>
<p>Note that you can't reliably block or unblock a signal from its own signal
handler if you're using safe signals. Other signals can be blocked or unblocked
reliably.</p>
</li>
<li><a name="sigsetjmp"></a><b><code class="inline"><span class="w">sigsetjmp</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">sigsetjmp</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific: use <code class="inline"><a class="l_k" href="functions/eval.html">eval</a> <span class="s">{</span><span class="s">}</span></code>
 instead,
see <a href="functions/eval.html">eval</a>.</p>
</li>
<li><a name="sigsuspend"></a><b><code class="inline"><span class="w">sigsuspend</span></code>
</b>
<p>Install a signal mask and suspend process until signal arrives.  This uses
<code class="inline"><span class="w">POSIX::SigSet</span></code>
 objects for the <code class="inline"><span class="w">signal_mask</span></code>
 argument.  Consult your
system's <code class="inline"><span class="w">sigsuspend</span></code>
 manpage for details.</p>
<p>Synopsis:</p>
<pre class="verbatim"><ol><li>	<span class="i">sigsuspend</span><span class="s">(</span><span class="w">signal_mask</span><span class="s">)</span></li></ol></pre><p>Returns <code class="inline"><a class="l_k" href="functions/undef.html">undef</a></code> on failure.</p>
</li>
<li><a name="sin"></a><b><code class="inline"><a class="l_k" href="functions/sin.html">sin</a></code></b>
<p>This is identical to Perl's builtin <code class="inline"><a class="l_k" href="functions/sin.html">sin()</a></code> function
for returning the sine of the numerical argument,
see <a href="functions/sin.html">sin</a>.  See also <a href="Math/Trig.html">Math::Trig</a>.</p>
</li>
<li><a name="sinh"></a><b><code class="inline"><span class="w">sinh</span></code>
</b>
<p>This is identical to the C function <code class="inline"><span class="i">sinh</span><span class="s">(</span><span class="s">)</span></code>

for returning the hyperbolic sine of the numerical argument.
See also <a href="Math/Trig.html">Math::Trig</a>.</p>
</li>
<li><a name="sleep"></a><b><code class="inline"><a class="l_k" href="functions/sleep.html">sleep</a></code></b>
<p>This is functionally identical to Perl's builtin <code class="inline"><a class="l_k" href="functions/sleep.html">sleep()</a></code> function
for suspending the execution of the current for process for certain
number of seconds, see <a href="functions/sleep.html">sleep</a>.  There is one significant
difference, however: <code class="inline"><span class="i">POSIX::sleep</span><span class="s">(</span><span class="s">)</span></code>
 returns the number of
<b>unslept</b> seconds, while the <code class="inline"><span class="i">CORE::sleep</span><span class="s">(</span><span class="s">)</span></code>
 returns the
number of slept seconds.</p>
</li>
<li><a name="sprintf"></a><b><code class="inline"><a class="l_k" href="functions/sprintf.html">sprintf</a></code></b>
<p>This is similar to Perl's builtin <code class="inline"><a class="l_k" href="functions/sprintf.html">sprintf()</a></code> function
for returning a string that has the arguments formatted as requested,
see <a href="functions/sprintf.html">sprintf</a>.</p>
</li>
<li><a name="sqrt"></a><b><code class="inline"><a class="l_k" href="functions/sqrt.html">sqrt</a></code></b>
<p>This is identical to Perl's builtin <code class="inline"><a class="l_k" href="functions/sqrt.html">sqrt()</a></code> function.
for returning the square root of the numerical argument,
see <a href="functions/sqrt.html">sqrt</a>.</p>
</li>
<li><a name="srand"></a><b><code class="inline"><a class="l_k" href="functions/srand.html">srand</a></code></b>
<p>Give a seed the pseudorandom number generator, see <a href="functions/srand.html">srand</a>.</p>
</li>
<li><a name="sscanf"></a><b><code class="inline"><span class="w">sscanf</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">sscanf</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific, use regular expressions instead,
see <a href="perlre.html">perlre</a>.</p>
</li>
<li><a name="stat"></a><b><code class="inline"><a class="l_k" href="functions/stat.html">stat</a></code></b>
<p>This is identical to Perl's builtin <code class="inline"><a class="l_k" href="functions/stat.html">stat()</a></code> function
for returning information about files and directories.</p>
</li>
<li><a name="strcat"></a><b><code class="inline"><span class="w">strcat</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">strcat</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific, use <code class="inline">.=</code>
 instead, see <a href="perlop.html">perlop</a>.</p>
</li>
<li><a name="strchr"></a><b><code class="inline"><span class="w">strchr</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">strchr</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific, see <a href="functions/index.html">index</a> instead.</p>
</li>
<li><a name="strcmp"></a><b><code class="inline"><span class="w">strcmp</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">strcmp</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific, use <code class="inline">eq</code>
 or <code class="inline">cmp</code>
 instead, see <a href="perlop.html">perlop</a>.</p>
</li>
<li><a name="strcoll"></a><b><code class="inline"><span class="w">strcoll</span></code>
</b>
<p>This is identical to the C function <code class="inline"><span class="i">strcoll</span><span class="s">(</span><span class="s">)</span></code>

for collating (comparing) strings transformed using
the <code class="inline"><span class="i">strxfrm</span><span class="s">(</span><span class="s">)</span></code>
 function.  Not really needed since
Perl can do this transparently, see <a href="perllocale.html">perllocale</a>.</p>
<p>Beware that in a UTF-8 locale, anything you pass to this function must
be in UTF-8; and when not in a UTF-8 locale, anything passed must not be
UTF-8 encoded.</p>
</li>
<li><a name="strcpy"></a><b><code class="inline"><span class="w">strcpy</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">strcpy</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific, use <code class="inline">=</code>
 instead, see <a href="perlop.html">perlop</a>.</p>
</li>
<li><a name="strcspn"></a><b><code class="inline"><span class="w">strcspn</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">strcspn</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific, use regular expressions instead,
see <a href="perlre.html">perlre</a>.</p>
</li>
<li><a name="strerror"></a><b><code class="inline"><span class="w">strerror</span></code>
</b>
<p>Returns the error string for the specified errno.
Identical to the string form of <code class="inline"><span class="i">$!</span></code>
, see <a href="perlvar.html#%24ERRNO">$ERRNO in perlvar</a>.</p>
</li>
<li><a name="strftime"></a><b><code class="inline"><span class="w">strftime</span></code>
</b>
<p>Convert date and time information to string.  Returns the string.</p>
<p>Synopsis:</p>
<pre class="verbatim"><ol><li>	<span class="i">strftime</span><span class="s">(</span><span class="w">fmt</span><span class="cm">,</span> <span class="w">sec</span><span class="cm">,</span> <span class="w">min</span><span class="cm">,</span> <span class="w">hour</span><span class="cm">,</span> <span class="w">mday</span><span class="cm">,</span> <span class="w">mon</span><span class="cm">,</span> <span class="w">year</span><span class="cm">,</span></li><li>		 <span class="w">wday</span> = <span class="n">-1</span><span class="cm">,</span> <span class="w">yday</span> = <span class="n">-1</span><span class="cm">,</span> <span class="w">isdst</span> = <span class="n">-1</span><span class="s">)</span></li></ol></pre><p>The month (<code class="inline"><span class="w">mon</span></code>
), weekday (<code class="inline"><span class="w">wday</span></code>
), and yearday (<code class="inline"><span class="w">yday</span></code>
) begin at zero,
<i>i.e.</i>, January is 0, not 1; Sunday is 0, not 1; January 1st is 0, not 1.  The
year (<code class="inline"><span class="w">year</span></code>
) is given in years since 1900, <i>i.e.</i>, the year 1995 is 95; the
year 2001 is 101.  Consult your system's <code class="inline"><span class="i">strftime</span><span class="s">(</span><span class="s">)</span></code>
 manpage for details
about these and the other arguments.</p>
<p>If you want your code to be portable, your format (<code class="inline"><span class="w">fmt</span></code>
) argument
should use only the conversion specifiers defined by the ANSI C
standard (C89, to play safe).  These are <code class="inline"><span class="w">aAbBcdHIjmMpSUwWxXyYZ</span>%</code>
.
But even then, the <b>results</b> of some of the conversion specifiers are
non-portable.  For example, the specifiers <code class="inline"><span class="w">aAbBcpZ</span></code>
 change according
to the locale settings of the user, and both how to set locales (the
locale names) and what output to expect are non-standard.
The specifier <code class="inline"><span class="w">c</span></code>
 changes according to the timezone settings of the
user and the timezone computation rules of the operating system.
The <code class="inline"><span class="w">Z</span></code>
 specifier is notoriously unportable since the names of
timezones are non-standard. Sticking to the numeric specifiers is the
safest route.</p>
<p>The given arguments are made consistent as though by calling
<code class="inline"><span class="i">mktime</span><span class="s">(</span><span class="s">)</span></code>
 before calling your system's <code class="inline"><span class="i">strftime</span><span class="s">(</span><span class="s">)</span></code>
 function,
except that the <code class="inline"><span class="w">isdst</span></code>
 value is not affected.</p>
<p>The string for Tuesday, December 12, 1995.</p>
<pre class="verbatim"><ol><li>	<span class="i">$str</span> = <span class="i">POSIX::strftime</span><span class="s">(</span> <span class="q">&quot;%A, %B %d, %Y&quot;</span><span class="cm">,</span></li><li>				 <span class="n">0</span><span class="cm">,</span> <span class="n">0</span><span class="cm">,</span> <span class="n">0</span><span class="cm">,</span> <span class="n">12</span><span class="cm">,</span> <span class="n">11</span><span class="cm">,</span> <span class="n">95</span><span class="cm">,</span> <span class="n">2</span> <span class="s">)</span><span class="sc">;</span></li><li>	<a class="l_k" href="functions/print.html">print</a> <span class="q">&quot;$str\n&quot;</span><span class="sc">;</span></li></ol></pre></li>
<li><a name="strlen"></a><b><code class="inline"><span class="w">strlen</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">strlen</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific, use <code class="inline"><a class="l_k" href="functions/length.html">length()</a></code> instead, see <a href="functions/length.html">length</a>.</p>
</li>
<li><a name="strncat"></a><b><code class="inline"><span class="w">strncat</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">strncat</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific, use <code class="inline">.=</code>
 instead, see <a href="perlop.html">perlop</a>.</p>
</li>
<li><a name="strncmp"></a><b><code class="inline"><span class="w">strncmp</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">strncmp</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific, use <code class="inline">eq</code>
 instead, see <a href="perlop.html">perlop</a>.</p>
</li>
<li><a name="strncpy"></a><b><code class="inline"><span class="w">strncpy</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">strncpy</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific, use <code class="inline">=</code>
 instead, see <a href="perlop.html">perlop</a>.</p>
</li>
<li><a name="strpbrk"></a><b><code class="inline"><span class="w">strpbrk</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">strpbrk</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific, use regular expressions instead,
see <a href="perlre.html">perlre</a>.</p>
</li>
<li><a name="strrchr"></a><b><code class="inline"><span class="w">strrchr</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">strrchr</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific, see <a href="functions/rindex.html">rindex</a> instead.</p>
</li>
<li><a name="strspn"></a><b><code class="inline"><span class="w">strspn</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">strspn</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific, use regular expressions instead,
see <a href="perlre.html">perlre</a>.</p>
</li>
<li><a name="strstr"></a><b><code class="inline"><span class="w">strstr</span></code>
</b>
<p>This is identical to Perl's builtin <code class="inline"><a class="l_k" href="functions/index.html">index()</a></code> function,
see <a href="functions/index.html">index</a>.</p>
</li>
<li><a name="strtod"></a><b><code class="inline"><span class="w">strtod</span></code>
</b>
<p>String to double translation. Returns the parsed number and the number
of characters in the unparsed portion of the string.  Truly
POSIX-compliant systems set <code class="inline"><span class="i">$!</span></code>
 (<code class="inline"><span class="i">$ERRNO</span></code>
) to indicate a translation
error, so clear <code class="inline"><span class="i">$!</span></code>
 before calling <code class="inline"><span class="w">strtod</span></code>
.  However, non-POSIX systems
may not check for overflow, and therefore will never set <code class="inline"><span class="i">$!</span></code>
.</p>
<p><code class="inline"><span class="w">strtod</span></code>
 respects any POSIX <code class="inline"><span class="i">setlocale</span><span class="s">(</span><span class="s">)</span></code>
 <code class="inline"><span class="w">LC_TIME</span></code>
 settings,
regardless of whether or not it is called from Perl code that is within
the scope of <code class="inline"><a class="l_k" href="functions/use.html">use</a> <span class="w">locale</span></code>
.</p>
<p>To parse a string <code class="inline"><span class="i">$str</span></code>
 as a floating point number use</p>
<pre class="verbatim"><ol><li>    <span class="i">$!</span> = <span class="n">0</span><span class="sc">;</span></li><li>    <span class="s">(</span><span class="i">$num</span><span class="cm">,</span> <span class="i">$n_unparsed</span><span class="s">)</span> = <span class="i">POSIX::strtod</span><span class="s">(</span><span class="i">$str</span><span class="s">)</span><span class="sc">;</span></li></ol></pre><p>The second returned item and <code class="inline"><span class="i">$!</span></code>
 can be used to check for valid input:</p>
<pre class="verbatim"><ol><li>    if <span class="s">(</span><span class="s">(</span><span class="i">$str</span> eq <span class="q">&#39;&#39;</span><span class="s">)</span> || <span class="s">(</span><span class="i">$n_unparsed</span> != <span class="n">0</span><span class="s">)</span> || <span class="i">$!</span><span class="s">)</span> <span class="s">{</span></li><li>        <a class="l_k" href="functions/die.html">die</a> <span class="q">&quot;Non-numeric input $str&quot;</span> . <span class="s">(</span><span class="i">$!</span> ? <span class="q">&quot;: $!\n&quot;</span> <span class="co">:</span> <span class="q">&quot;\n&quot;</span><span class="s">)</span><span class="sc">;</span></li><li>    <span class="s">}</span></li></ol></pre><p>When called in a scalar context <code class="inline"><span class="w">strtod</span></code>
 returns the parsed number.</p>
</li>
<li><a name="strtok"></a><b><code class="inline"><span class="w">strtok</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">strtok</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific, use regular expressions instead, see
<a href="perlre.html">perlre</a>, or <a href="functions/split.html">split</a>.</p>
</li>
<li><a name="strtol"></a><b><code class="inline"><span class="w">strtol</span></code>
</b>
<p>String to (long) integer translation.  Returns the parsed number and
the number of characters in the unparsed portion of the string.  Truly
POSIX-compliant systems set <code class="inline"><span class="i">$!</span></code>
 (<code class="inline"><span class="i">$ERRNO</span></code>
) to indicate a translation
error, so clear <code class="inline"><span class="i">$!</span></code>
 before calling <code class="inline"><span class="w">strtol</span></code>
.  However, non-POSIX systems
may not check for overflow, and therefore will never set <code class="inline"><span class="i">$!</span></code>
.</p>
<p><code class="inline"><span class="w">strtol</span></code>
 should respect any POSIX <i>setlocale()</i> settings.</p>
<p>To parse a string <code class="inline"><span class="i">$str</span></code>
 as a number in some base <code class="inline"><span class="i">$base</span></code>
 use</p>
<pre class="verbatim"><ol><li>    <span class="i">$!</span> = <span class="n">0</span><span class="sc">;</span></li><li>    <span class="s">(</span><span class="i">$num</span><span class="cm">,</span> <span class="i">$n_unparsed</span><span class="s">)</span> = <span class="i">POSIX::strtol</span><span class="s">(</span><span class="i">$str</span><span class="cm">,</span> <span class="i">$base</span><span class="s">)</span><span class="sc">;</span></li></ol></pre><p>The base should be zero or between 2 and 36, inclusive.  When the base
is zero or omitted <code class="inline"><span class="w">strtol</span></code>
 will use the string itself to determine the
base: a leading "0x" or "0X" means hexadecimal; a leading "0" means
octal; any other leading characters mean decimal.  Thus, "1234" is
parsed as a decimal number, "01234" as an octal number, and "0x1234"
as a hexadecimal number.</p>
<p>The second returned item and <code class="inline"><span class="i">$!</span></code>
 can be used to check for valid input:</p>
<pre class="verbatim"><ol><li>    if <span class="s">(</span><span class="s">(</span><span class="i">$str</span> eq <span class="q">&#39;&#39;</span><span class="s">)</span> || <span class="s">(</span><span class="i">$n_unparsed</span> != <span class="n">0</span><span class="s">)</span> || !<span class="i">$!</span><span class="s">)</span> <span class="s">{</span></li><li>        <a class="l_k" href="functions/die.html">die</a> <span class="q">&quot;Non-numeric input $str&quot;</span> . <span class="i">$!</span> ? <span class="q">&quot;: $!\n&quot;</span> <span class="co">:</span> <span class="q">&quot;\n&quot;</span><span class="sc">;</span></li><li>    <span class="s">}</span></li></ol></pre><p>When called in a scalar context <code class="inline"><span class="w">strtol</span></code>
 returns the parsed number.</p>
</li>
<li><a name="strtold"></a><b><code class="inline"><span class="w">strtold</span></code>
</b>
<p>Like <a href="#strtod">strtod</a> but for long doubles.  Defined only if the
system supports long doubles.</p>
</li>
<li><a name="strtoul"></a><b><code class="inline"><span class="w">strtoul</span></code>
</b>
<p>String to unsigned (long) integer translation.  <code class="inline"><span class="i">strtoul</span><span class="s">(</span><span class="s">)</span></code>
 is identical
to <code class="inline"><span class="i">strtol</span><span class="s">(</span><span class="s">)</span></code>
 except that <code class="inline"><span class="i">strtoul</span><span class="s">(</span><span class="s">)</span></code>
 only parses unsigned integers.  See
<a href="#strtol">strtol</a> for details.</p>
<p>Note: Some vendors supply <code class="inline"><span class="i">strtod</span><span class="s">(</span><span class="s">)</span></code>
 and <code class="inline"><span class="i">strtol</span><span class="s">(</span><span class="s">)</span></code>
 but not <code class="inline"><span class="i">strtoul</span><span class="s">(</span><span class="s">)</span></code>
.
Other vendors that do supply <code class="inline"><span class="i">strtoul</span><span class="s">(</span><span class="s">)</span></code>
 parse "-1" as a valid value.</p>
</li>
<li><a name="strxfrm"></a><b><code class="inline"><span class="w">strxfrm</span></code>
</b>
<p>String transformation.  Returns the transformed string.</p>
<pre class="verbatim"><ol><li>	<span class="i">$dst</span> = <span class="i">POSIX::strxfrm</span><span class="s">(</span> <span class="i">$src</span> <span class="s">)</span><span class="sc">;</span></li></ol></pre><p>Used in conjunction with the <code class="inline"><span class="i">strcoll</span><span class="s">(</span><span class="s">)</span></code>
 function, see <a href="#strcoll">strcoll</a>.</p>
<p>Not really needed since Perl can do this transparently, see
<a href="perllocale.html">perllocale</a>.</p>
<p>Beware that in a UTF-8 locale, anything you pass to this function must
be in UTF-8; and when not in a UTF-8 locale, anything passed must not be
UTF-8 encoded.</p>
</li>
<li><a name="sysconf"></a><b><code class="inline"><span class="w">sysconf</span></code>
</b>
<p>Retrieves values of system configurable variables.</p>
<p>The following will get the machine's clock speed.</p>
<pre class="verbatim"><ol><li>	<span class="i">$clock_ticks</span> = <span class="i">POSIX::sysconf</span><span class="s">(</span> <span class="i">&amp;POSIX::_SC_CLK_TCK</span> <span class="s">)</span><span class="sc">;</span></li></ol></pre><p>Returns <code class="inline"><a class="l_k" href="functions/undef.html">undef</a></code> on failure.</p>
</li>
<li><a name="system"></a><b><code class="inline"><a class="l_k" href="functions/system.html">system</a></code></b>
<p>This is identical to Perl's builtin <code class="inline"><a class="l_k" href="functions/system.html">system()</a></code> function, see
<a href="functions/system.html">system</a>.</p>
</li>
<li><a name="tan"></a><b><code class="inline"><span class="w">tan</span></code>
</b>
<p>This is identical to the C function <code class="inline"><span class="i">tan</span><span class="s">(</span><span class="s">)</span></code>
, returning the
tangent of the numerical argument.  See also <a href="Math/Trig.html">Math::Trig</a>.</p>
</li>
<li><a name="tanh"></a><b><code class="inline"><span class="w">tanh</span></code>
</b>
<p>This is identical to the C function <code class="inline"><span class="i">tanh</span><span class="s">(</span><span class="s">)</span></code>
, returning the
hyperbolic tangent of the numerical argument.   See also <a href="Math/Trig.html">Math::Trig</a>.</p>
</li>
<li><a name="tcdrain"></a><b><code class="inline"><span class="w">tcdrain</span></code>
</b>
<p>This is similar to the C function <code class="inline"><span class="i">tcdrain</span><span class="s">(</span><span class="s">)</span></code>
 for draining
the output queue of its argument stream.</p>
<p>Returns <code class="inline"><a class="l_k" href="functions/undef.html">undef</a></code> on failure.</p>
</li>
<li><a name="tcflow"></a><b><code class="inline"><span class="w">tcflow</span></code>
</b>
<p>This is similar to the C function <code class="inline"><span class="i">tcflow</span><span class="s">(</span><span class="s">)</span></code>
 for controlling
the flow of its argument stream.</p>
<p>Returns <code class="inline"><a class="l_k" href="functions/undef.html">undef</a></code> on failure.</p>
</li>
<li><a name="tcflush"></a><b><code class="inline"><span class="w">tcflush</span></code>
</b>
<p>This is similar to the C function <code class="inline"><span class="i">tcflush</span><span class="s">(</span><span class="s">)</span></code>
 for flushing
the I/O buffers of its argument stream.</p>
<p>Returns <code class="inline"><a class="l_k" href="functions/undef.html">undef</a></code> on failure.</p>
</li>
<li><a name="tcgetpgrp"></a><b><code class="inline"><span class="w">tcgetpgrp</span></code>
</b>
<p>This is identical to the C function <code class="inline"><span class="i">tcgetpgrp</span><span class="s">(</span><span class="s">)</span></code>
 for returning the
process group identifier of the foreground process group of the controlling
terminal.</p>
</li>
<li><a name="tcsendbreak"></a><b><code class="inline"><span class="w">tcsendbreak</span></code>
</b>
<p>This is similar to the C function <code class="inline"><span class="i">tcsendbreak</span><span class="s">(</span><span class="s">)</span></code>
 for sending
a break on its argument stream.</p>
<p>Returns <code class="inline"><a class="l_k" href="functions/undef.html">undef</a></code> on failure.</p>
</li>
<li><a name="tcsetpgrp"></a><b><code class="inline"><span class="w">tcsetpgrp</span></code>
</b>
<p>This is similar to the C function <code class="inline"><span class="i">tcsetpgrp</span><span class="s">(</span><span class="s">)</span></code>
 for setting the
process group identifier of the foreground process group of the controlling
terminal.</p>
<p>Returns <code class="inline"><a class="l_k" href="functions/undef.html">undef</a></code> on failure.</p>
</li>
<li><a name="tgamma"></a><b><code class="inline"><span class="w">tgamma</span></code>
</b>
<p>The Gamma function [C99].</p>
<p>See also <a href="#lgamma">lgamma</a>.</p>
</li>
<li><a name="time"></a><b><code class="inline"><a class="l_k" href="functions/time.html">time</a></code></b>
<p>This is identical to Perl's builtin <code class="inline"><a class="l_k" href="functions/time.html">time()</a></code> function
for returning the number of seconds since the epoch
(whatever it is for the system), see <a href="functions/time.html">time</a>.</p>
</li>
<li><a name="times"></a><b><code class="inline"><a class="l_k" href="functions/times.html">times</a></code></b>
<p>The <code class="inline"><a class="l_k" href="functions/times.html">times()</a></code> function returns elapsed realtime since some point in the past
(such as system startup), user and system times for this process, and user
and system times used by child processes.  All times are returned in clock
ticks.</p>
<pre class="verbatim"><ol><li>    <span class="s">(</span><span class="i">$realtime</span><span class="cm">,</span> <span class="i">$user</span><span class="cm">,</span> <span class="i">$system</span><span class="cm">,</span> <span class="i">$cuser</span><span class="cm">,</span> <span class="i">$csystem</span><span class="s">)</span></li><li>	= <span class="i">POSIX::times</span><span class="s">(</span><span class="s">)</span><span class="sc">;</span></li></ol></pre><p>Note: Perl's builtin <code class="inline"><a class="l_k" href="functions/times.html">times()</a></code> function returns four values, measured in
seconds.</p>
</li>
<li><a name="tmpfile"></a><b><code class="inline"><span class="w">tmpfile</span></code>
</b>
<p>Not implemented.  Use method <code class="inline"><span class="i">IO::File::new_tmpfile</span><span class="s">(</span><span class="s">)</span></code>
 instead, or see <a href="File/Temp.html">File::Temp</a>.</p>
</li>
<li><a name="tmpnam"></a><b><code class="inline"><span class="w">tmpnam</span></code>
</b>
<p>For security reasons, which are probably detailed in your system's
documentation for the C library <code class="inline"><span class="i">tmpnam</span><span class="s">(</span><span class="s">)</span></code>
 function, this interface
is no longer available; instead use <a href="File/Temp.html">File::Temp</a>.</p>
</li>
<li><a name="tolower"></a><b><code class="inline"><span class="w">tolower</span></code>
</b>
<p>This is identical to the C function, except that it can apply to a single
character or to a whole string, and currently operates as if the locale
always is "C".  Consider using the <code class="inline"><a class="l_k" href="functions/lc.html">lc()</a></code> function, see <a href="functions/lc.html">lc</a>,
see <a href="functions/lc.html">lc</a>, or the equivalent <code class="inline">\<span class="w">L</span></code>
 operator inside doublequotish
strings.</p>
</li>
<li><a name="toupper"></a><b><code class="inline"><span class="w">toupper</span></code>
</b>
<p>This is similar to the C function, except that it can apply to a single
character or to a whole string, and currently operates as if the locale
always is "C".  Consider using the <code class="inline"><a class="l_k" href="functions/uc.html">uc()</a></code> function, see <a href="functions/uc.html">uc</a>,
or the equivalent <code class="inline">\<span class="w">U</span></code>
 operator inside doublequotish strings.</p>
</li>
<li><a name="trunc"></a><b><code class="inline"><span class="w">trunc</span></code>
</b>
<p>Returns the integer toward zero from the argument [C99].</p>
<p>See also <a href="#ceil">ceil</a>, <a href="#floor">floor</a>, and <a href="#round">round</a>.</p>
</li>
<li><a name="ttyname"></a><b><code class="inline"><span class="w">ttyname</span></code>
</b>
<p>This is identical to the C function <code class="inline"><span class="i">ttyname</span><span class="s">(</span><span class="s">)</span></code>
 for returning the
name of the current terminal.</p>
</li>
<li><a name="tzname"></a><b><code class="inline"><span class="w">tzname</span></code>
</b>
<p>Retrieves the time conversion information from the <code class="inline"><span class="w">tzname</span></code>
 variable.</p>
<pre class="verbatim"><ol><li>	<span class="i">POSIX::tzset</span><span class="s">(</span><span class="s">)</span><span class="sc">;</span></li><li>	<span class="s">(</span><span class="i">$std</span><span class="cm">,</span> <span class="i">$dst</span><span class="s">)</span> = <span class="i">POSIX::tzname</span><span class="s">(</span><span class="s">)</span><span class="sc">;</span></li></ol></pre></li>
<li><a name="tzset"></a><b><code class="inline"><span class="w">tzset</span></code>
</b>
<p>This is identical to the C function <code class="inline"><span class="i">tzset</span><span class="s">(</span><span class="s">)</span></code>
 for setting
the current timezone based on the environment variable <code class="inline"><span class="w">TZ</span></code>
,
to be used by <code class="inline"><span class="i">ctime</span><span class="s">(</span><span class="s">)</span></code>
, <code class="inline"><a class="l_k" href="functions/localtime.html">localtime()</a></code>, <code class="inline"><span class="i">mktime</span><span class="s">(</span><span class="s">)</span></code>
, and <code class="inline"><span class="i">strftime</span><span class="s">(</span><span class="s">)</span></code>

functions.</p>
</li>
<li><a name="umask"></a><b><code class="inline"><a class="l_k" href="functions/umask.html">umask</a></code></b>
<p>This is identical to Perl's builtin <code class="inline"><a class="l_k" href="functions/umask.html">umask()</a></code> function
for setting (and querying) the file creation permission mask,
see <a href="functions/umask.html">umask</a>.</p>
</li>
<li><a name="uname"></a><b><code class="inline"><span class="w">uname</span></code>
</b>
<p>Get name of current operating system.</p>
<pre class="verbatim"><ol><li>	<span class="s">(</span><span class="i">$sysname</span><span class="cm">,</span> <span class="i">$nodename</span><span class="cm">,</span> <span class="i">$release</span><span class="cm">,</span> <span class="i">$version</span><span class="cm">,</span> <span class="i">$machine</span><span class="s">)</span></li><li>		= <span class="i">POSIX::uname</span><span class="s">(</span><span class="s">)</span><span class="sc">;</span></li></ol></pre><p>Note that the actual meanings of the various fields are not
that well standardized, do not expect any great portability.
The <code class="inline"><span class="i">$sysname</span></code>
 might be the name of the operating system,
the <code class="inline"><span class="i">$nodename</span></code>
 might be the name of the host, the <code class="inline"><span class="i">$release</span></code>

might be the (major) release number of the operating system,
the <code class="inline"><span class="i">$version</span></code>
 might be the (minor) release number of the
operating system, and the <code class="inline"><span class="i">$machine</span></code>
 might be a hardware identifier.
Maybe.</p>
</li>
<li><a name="ungetc"></a><b><code class="inline"><span class="w">ungetc</span></code>
</b>
<p>Not implemented.  Use method <code class="inline"><span class="i">IO::Handle::ungetc</span><span class="s">(</span><span class="s">)</span></code>
 instead.</p>
</li>
<li><a name="unlink"></a><b><code class="inline"><a class="l_k" href="functions/unlink.html">unlink</a></code></b>
<p>This is identical to Perl's builtin <code class="inline"><a class="l_k" href="functions/unlink.html">unlink()</a></code> function
for removing files, see <a href="functions/unlink.html">unlink</a>.</p>
</li>
<li><a name="utime"></a><b><code class="inline"><a class="l_k" href="functions/utime.html">utime</a></code></b>
<p>This is identical to Perl's builtin <code class="inline"><a class="l_k" href="functions/utime.html">utime()</a></code> function
for changing the time stamps of files and directories,
see <a href="functions/utime.html">utime</a>.</p>
</li>
<li><a name="vfprintf"></a><b><code class="inline"><span class="w">vfprintf</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">vfprintf</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific, see <a href="functions/printf.html">printf</a> instead.</p>
</li>
<li><a name="vprintf"></a><b><code class="inline"><span class="w">vprintf</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">vprintf</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific, see <a href="functions/printf.html">printf</a> instead.</p>
</li>
<li><a name="vsprintf"></a><b><code class="inline"><span class="w">vsprintf</span></code>
</b>
<p>Not implemented.  <code class="inline"><span class="i">vsprintf</span><span class="s">(</span><span class="s">)</span></code>
 is C-specific, see <a href="functions/sprintf.html">sprintf</a> instead.</p>
</li>
<li><a name="wait"></a><b><code class="inline"><a class="l_k" href="functions/wait.html">wait</a></code></b>
<p>This is identical to Perl's builtin <code class="inline"><a class="l_k" href="functions/wait.html">wait()</a></code> function,
see <a href="functions/wait.html">wait</a>.</p>
</li>
<li><a name="waitpid"></a><b><code class="inline"><a class="l_k" href="functions/waitpid.html">waitpid</a></code></b>
<p>Wait for a child process to change state.  This is identical to Perl's
builtin <code class="inline"><a class="l_k" href="functions/waitpid.html">waitpid()</a></code> function, see <a href="functions/waitpid.html">waitpid</a>.</p>
<pre class="verbatim"><ol><li>	<span class="i">$pid</span> = <span class="i">POSIX::waitpid</span><span class="s">(</span> <span class="n">-1</span><span class="cm">,</span> <span class="w">POSIX::WNOHANG</span> <span class="s">)</span><span class="sc">;</span></li><li>	<a class="l_k" href="functions/print.html">print</a> <span class="q">&quot;status = &quot;</span><span class="cm">,</span> <span class="s">(</span><span class="i">$?</span> / <span class="n">256</span><span class="s">)</span><span class="cm">,</span> <span class="q">&quot;\n&quot;</span><span class="sc">;</span></li></ol></pre></li>
<li><a name="wcstombs"></a><b><code class="inline"><span class="w">wcstombs</span></code>
</b>
<p>This is identical to the C function <code class="inline"><span class="i">wcstombs</span><span class="s">(</span><span class="s">)</span></code>
.</p>
<p>See <a href="#mblen">mblen</a>.</p>
</li>
<li><a name="wctomb"></a><b><code class="inline"><span class="w">wctomb</span></code>
</b>
<p>This is identical to the C function <code class="inline"><span class="i">wctomb</span><span class="s">(</span><span class="s">)</span></code>
.</p>
<p>See <a href="#mblen">mblen</a>.</p>
</li>
<li><a name="write"></a><b><code class="inline"><a class="l_k" href="functions/write.html">write</a></code></b>
<p>Write to a file.  This uses file descriptors such as those obtained by
calling <code class="inline"><span class="w">POSIX::open</span></code>
.</p>
<pre class="verbatim"><ol><li>	<span class="i">$fd</span> = <span class="i">POSIX::open</span><span class="s">(</span> <span class="q">&quot;foo&quot;</span><span class="cm">,</span> <span class="i">&amp;POSIX::O_WRONLY</span> <span class="s">)</span><span class="sc">;</span></li><li>	<span class="i">$buf</span> = <span class="q">&quot;hello&quot;</span><span class="sc">;</span></li><li>	<span class="i">$bytes</span> = <span class="i">POSIX::write</span><span class="s">(</span> <span class="i">$fd</span><span class="cm">,</span> <span class="i">$buf</span><span class="cm">,</span> <span class="n">5</span> <span class="s">)</span><span class="sc">;</span></li></ol></pre><p>Returns <code class="inline"><a class="l_k" href="functions/undef.html">undef</a></code> on failure.</p>
<p>See also <a href="functions/syswrite.html">syswrite</a>.</p>
</li>
</ul>
<a name="CLASSES"></a><h1>CLASSES</h1>
<a name="POSIX%3a%3aSigAction"></a><h2><code class="inline"><span class="w">POSIX::SigAction</span></code>
</h2>
<ul>
<li><a name="new"></a><b><code class="inline"><span class="w">new</span></code>
</b>
<p>Creates a new <code class="inline"><span class="w">POSIX::SigAction</span></code>
 object which corresponds to the C
<code class="inline"><span class="w">struct</span> <span class="w">sigaction</span></code>
.  This object will be destroyed automatically when
it is no longer needed.  The first parameter is the handler, a sub
reference.  The second parameter is a <code class="inline"><span class="w">POSIX::SigSet</span></code>
 object, it
defaults to the empty set.  The third parameter contains the
<code class="inline"><span class="w">sa_flags</span></code>
, it defaults to 0.</p>
<pre class="verbatim"><ol><li>	<span class="i">$sigset</span> = <span class="w">POSIX::SigSet</span><span class="w">-&gt;new</span><span class="s">(</span><span class="w">SIGINT</span><span class="cm">,</span> <span class="w">SIGQUIT</span><span class="s">)</span><span class="sc">;</span></li><li>	<span class="i">$sigaction</span> = <span class="w">POSIX::SigAction</span><span class="w">-&gt;new</span><span class="s">(</span></li><li>			\<span class="i">&amp;handler</span><span class="cm">,</span> <span class="i">$sigset</span><span class="cm">,</span> <span class="i">&amp;POSIX::SA_NOCLDSTOP</span></li><li>		     <span class="s">)</span><span class="sc">;</span></li></ol></pre><p>This <code class="inline"><span class="w">POSIX::SigAction</span></code>
 object is intended for use with the <code class="inline"><span class="i">POSIX::sigaction</span><span class="s">(</span><span class="s">)</span></code>

function.</p>
</li>
</ul>
<ul>
<li><a name="handler"></a><b><code class="inline"><span class="w">handler</span></code>
</b>
</li>
<li><a name="mask"></a><b><code class="inline"><span class="w">mask</span></code>
</b>
</li>
<li><a name="flags"></a><b><code class="inline"><span class="w">flags</span></code>
</b>
<p>accessor functions to get/set the values of a SigAction object.</p>
<pre class="verbatim"><ol><li>	<span class="i">$sigset</span> = <span class="i">$sigaction</span><span class="i">-&gt;mask</span><span class="sc">;</span></li><li>	<span class="i">$sigaction</span><span class="i">-&gt;flags</span><span class="s">(</span><span class="i">&amp;POSIX::SA_RESTART</span><span class="s">)</span><span class="sc">;</span></li></ol></pre></li>
<li><a name="safe"></a><b><code class="inline"><span class="w">safe</span></code>
</b>
<p>accessor function for the "safe signals" flag of a SigAction object; see
<a href="perlipc.html">perlipc</a> for general information on safe (a.k.a. "deferred") signals.  If
you wish to handle a signal safely, use this accessor to set the "safe" flag
in the <code class="inline"><span class="w">POSIX::SigAction</span></code>
 object:</p>
<pre class="verbatim"><ol><li>	<span class="i">$sigaction</span><span class="i">-&gt;safe</span><span class="s">(</span><span class="n">1</span><span class="s">)</span><span class="sc">;</span></li></ol></pre><p>You may also examine the "safe" flag on the output action object which is
filled in when given as the third parameter to <code class="inline"><span class="i">POSIX::sigaction</span><span class="s">(</span><span class="s">)</span></code>
:</p>
<pre class="verbatim"><ol><li>	<span class="i">sigaction</span><span class="s">(</span><span class="w">SIGINT</span><span class="cm">,</span> <span class="i">$new_action</span><span class="cm">,</span> <span class="i">$old_action</span><span class="s">)</span><span class="sc">;</span></li><li>	if <span class="s">(</span><span class="i">$old_action</span><span class="i">-&gt;safe</span><span class="s">)</span> <span class="s">{</span></li><li>	    <span class="c"># previous SIGINT handler used safe signals</span></li><li>	<span class="s">}</span></li></ol></pre></li>
</ul>
<a name="POSIX%3a%3aSigRt"></a><h2><code class="inline"><span class="w">POSIX::SigRt</span></code>
</h2>
<ul>
<li><a name="%25SIGRT"></a><b><code class="inline"><span class="i">%SIGRT</span></code>
</b>
<p>A hash of the POSIX realtime signal handlers.  It is an extension of
the standard <code class="inline"><span class="i">%SIG</span></code>
, the <code class="inline"><span class="i">$POSIX::SIGRT</span>{<span class="w">SIGRTMIN</span>}</code>
 is roughly equivalent
to <code class="inline"><span class="i">$SIG</span>{<span class="w">SIGRTMIN</span>}</code>
, but the right POSIX moves (see below) are made with
the <code class="inline"><span class="w">POSIX::SigSet</span></code>
 and <code class="inline"><span class="w">POSIX::sigaction</span></code>
 instead of accessing the <code class="inline"><span class="i">%SIG</span></code>
.</p>
<p>You can set the <code class="inline"><span class="i">%POSIX::SIGRT</span></code>
 elements to set the POSIX realtime
signal handlers, use <code class="inline"><a class="l_k" href="functions/delete.html">delete</a></code> and <code class="inline"><a class="l_k" href="functions/exists.html">exists</a></code> on the elements, and use
<code class="inline"><a class="l_k" href="functions/scalar.html">scalar</a></code> on the <code class="inline"><span class="i">%POSIX::SIGRT</span></code>
 to find out how many POSIX realtime
signals there are available <code class="inline"><span class="s">(</span><span class="w">SIGRTMAX</span> - <span class="w">SIGRTMIN</span> + <span class="n">1</span></code>
, the <code class="inline"><span class="w">SIGRTMAX</span></code>
 is
a valid POSIX realtime signal).</p>
<p>Setting the <code class="inline"><span class="i">%SIGRT</span></code>
 elements is equivalent to calling this:</p>
<pre class="verbatim"><ol><li><a name="new"></a>  sub <span class="m">new</span> <span class="s">{</span></li><li>    <a class="l_k" href="functions/my.html">my</a> <span class="s">(</span><span class="i">$rtsig</span><span class="cm">,</span> <span class="i">$handler</span><span class="cm">,</span> <span class="i">$flags</span><span class="s">)</span> = <span class="i">@_</span><span class="sc">;</span></li><li>    <a class="l_k" href="functions/my.html">my</a> <span class="i">$sigset</span> = <span class="i">POSIX::SigSet</span><span class="s">(</span><span class="i">$rtsig</span><span class="s">)</span><span class="sc">;</span></li><li>    <a class="l_k" href="functions/my.html">my</a> <span class="i">$sigact</span> = <span class="w">POSIX::SigAction</span><span class="w">-&gt;new</span><span class="s">(</span><span class="i">$handler</span><span class="cm">,</span><span class="i">$sigset</span><span class="cm">,</span><span class="i">$flags</span><span class="s">)</span><span class="sc">;</span></li><li>    <span class="i">sigaction</span><span class="s">(</span><span class="i">$rtsig</span><span class="cm">,</span> <span class="i">$sigact</span><span class="s">)</span><span class="sc">;</span></li><li>  <span class="s">}</span></li></ol></pre><p>The flags default to zero, if you want something different you can
either use <code class="inline"><a class="l_k" href="functions/local.html">local</a></code> on <code class="inline"><span class="i">$POSIX::SigRt::SIGACTION_FLAGS</span></code>
, or you can
derive from POSIX::SigRt and define your own <code class="inline"><span class="i">new</span><span class="s">(</span><span class="s">)</span></code>
 (the tied hash
STORE method of the <code class="inline"><span class="i">%SIGRT</span></code>
 calls <code class="inline"><span class="i">new</span><span class="s">(</span><span class="i">$rtsig</span><span class="cm">,</span> <span class="i">$handler</span><span class="cm">,</span> <span class="i">$SIGACTION_FLAGS</span><span class="s">)</span></code>
,
where the <code class="inline"><span class="i">$rtsig</span></code>
 ranges from zero to <code class="inline"><span class="w">SIGRTMAX</span> - <span class="w">SIGRTMIN</span> + <span class="n">1</span><span class="p">)</span></code>
.</p>
<p>Just as with any signal, you can use <code class="inline"><span class="i">sigaction</span><span class="s">(</span><span class="i">$rtsig</span><span class="cm">,</span> <a class="l_k" href="functions/undef.html">undef</a><span class="cm">,</span> <span class="i">$oa</span><span class="s">)</span></code>
 to
retrieve the installed signal handler (or, rather, the signal action).</p>
<p><b>NOTE:</b> whether POSIX realtime signals really work in your system, or
whether Perl has been compiled so that it works with them, is outside
of this discussion.</p>
</li>
<li><a name="SIGRTMIN"></a><b><code class="inline"><span class="w">SIGRTMIN</span></code>
</b>
<p>Return the minimum POSIX realtime signal number available, or <code class="inline"><a class="l_k" href="functions/undef.html">undef</a></code>
if no POSIX realtime signals are available.</p>
</li>
<li><a name="SIGRTMAX"></a><b><code class="inline"><span class="w">SIGRTMAX</span></code>
</b>
<p>Return the maximum POSIX realtime signal number available, or <code class="inline"><a class="l_k" href="functions/undef.html">undef</a></code>
if no POSIX realtime signals are available.</p>
</li>
</ul>
<a name="POSIX%3a%3aSigSet"></a><h2><code class="inline"><span class="w">POSIX::SigSet</span></code>
</h2>
<ul>
<li><a name="new"></a><b><code class="inline"><span class="w">new</span></code>
</b>
<p>Create a new SigSet object.  This object will be destroyed automatically
when it is no longer needed.  Arguments may be supplied to initialize the
set.</p>
<p>Create an empty set.</p>
<pre class="verbatim"><ol><li>	<span class="i">$sigset</span> = <span class="w">POSIX::SigSet</span><span class="w">-&gt;new</span><span class="sc">;</span></li></ol></pre><p>Create a set with <code class="inline"><span class="w">SIGUSR1</span></code>
.</p>
<pre class="verbatim"><ol><li>	<span class="i">$sigset</span> = <span class="w">POSIX::SigSet</span><span class="w">-&gt;new</span><span class="s">(</span> <span class="i">&amp;POSIX::SIGUSR1</span> <span class="s">)</span><span class="sc">;</span></li></ol></pre></li>
<li><a name="addset"></a><b><code class="inline"><span class="w">addset</span></code>
</b>
<p>Add a signal to a SigSet object.</p>
<pre class="verbatim"><ol><li>	<span class="i">$sigset</span><span class="i">-&gt;addset</span><span class="s">(</span> <span class="i">&amp;POSIX::SIGUSR2</span> <span class="s">)</span><span class="sc">;</span></li></ol></pre><p>Returns <code class="inline"><a class="l_k" href="functions/undef.html">undef</a></code> on failure.</p>
</li>
<li><a name="delset"></a><b><code class="inline"><span class="w">delset</span></code>
</b>
<p>Remove a signal from the SigSet object.</p>
<pre class="verbatim"><ol><li>	<span class="i">$sigset</span><span class="i">-&gt;delset</span><span class="s">(</span> <span class="i">&amp;POSIX::SIGUSR2</span> <span class="s">)</span><span class="sc">;</span></li></ol></pre><p>Returns <code class="inline"><a class="l_k" href="functions/undef.html">undef</a></code> on failure.</p>
</li>
<li><a name="emptyset"></a><b><code class="inline"><span class="w">emptyset</span></code>
</b>
<p>Initialize the SigSet object to be empty.</p>
<pre class="verbatim"><ol><li>	<span class="i">$sigset</span><span class="i">-&gt;emptyset</span><span class="s">(</span><span class="s">)</span><span class="sc">;</span></li></ol></pre><p>Returns <code class="inline"><a class="l_k" href="functions/undef.html">undef</a></code> on failure.</p>
</li>
<li><a name="fillset"></a><b><code class="inline"><span class="w">fillset</span></code>
</b>
<p>Initialize the SigSet object to include all signals.</p>
<pre class="verbatim"><ol><li>	<span class="i">$sigset</span><span class="i">-&gt;fillset</span><span class="s">(</span><span class="s">)</span><span class="sc">;</span></li></ol></pre><p>Returns <code class="inline"><a class="l_k" href="functions/undef.html">undef</a></code> on failure.</p>
</li>
<li><a name="ismember"></a><b><code class="inline"><span class="w">ismember</span></code>
</b>
<p>Tests the SigSet object to see if it contains a specific signal.</p>
<pre class="verbatim"><ol><li>	if<span class="s">(</span> <span class="i">$sigset</span><span class="i">-&gt;ismember</span><span class="s">(</span> <span class="i">&amp;POSIX::SIGUSR1</span> <span class="s">)</span> <span class="s">)</span><span class="s">{</span></li><li>		<a class="l_k" href="functions/print.html">print</a> <span class="q">&quot;contains SIGUSR1\n&quot;</span><span class="sc">;</span></li><li>	<span class="s">}</span></li></ol></pre></li>
</ul>
<a name="POSIX%3a%3aTermios"></a><h2><code class="inline"><span class="w">POSIX::Termios</span></code>
</h2>
<ul>
<li><a name="new"></a><b><code class="inline"><span class="w">new</span></code>
</b>
<p>Create a new Termios object.  This object will be destroyed automatically
when it is no longer needed.  A Termios object corresponds to the <code class="inline"><span class="w">termios</span></code>

C struct.  <code class="inline"><span class="i">new</span><span class="s">(</span><span class="s">)</span></code>
 mallocs a new one, <code class="inline"><span class="i">getattr</span><span class="s">(</span><span class="s">)</span></code>
 fills it from a file descriptor,
and <code class="inline"><span class="i">setattr</span><span class="s">(</span><span class="s">)</span></code>
 sets a file descriptor's parameters to match Termios' contents.</p>
<pre class="verbatim"><ol><li>	<span class="i">$termios</span> = <span class="w">POSIX::Termios</span><span class="w">-&gt;new</span><span class="sc">;</span></li></ol></pre></li>
<li><a name="getattr"></a><b><code class="inline"><span class="w">getattr</span></code>
</b>
<p>Get terminal control attributes.</p>
<p>Obtain the attributes for <code class="inline"><span class="w">stdin</span></code>
.</p>
<pre class="verbatim"><ol><li>	$termios-&gt;getattr( 0 ) # Recommended for clarity.</li><li>	$termios-&gt;getattr()</li></ol></pre><p>Obtain the attributes for stdout.</p>
<pre class="verbatim"><ol><li>	<span class="i">$termios</span><span class="i">-&gt;getattr</span><span class="s">(</span> <span class="n">1</span> <span class="s">)</span></li></ol></pre><p>Returns <code class="inline"><a class="l_k" href="functions/undef.html">undef</a></code> on failure.</p>
</li>
<li><a name="getcc"></a><b><code class="inline"><span class="w">getcc</span></code>
</b>
<p>Retrieve a value from the <code class="inline"><span class="w">c_cc</span></code>
 field of a <code class="inline"><span class="w">termios</span></code>
 object.  The <code class="inline"><span class="w">c_cc</span></code>
 field is
an array so an index must be specified.</p>
<pre class="verbatim"><ol><li>	<span class="i">$c_cc</span>[<span class="n">1</span>] = <span class="i">$termios</span><span class="i">-&gt;getcc</span><span class="s">(</span><span class="n">1</span><span class="s">)</span><span class="sc">;</span></li></ol></pre></li>
<li><a name="getcflag"></a><b><code class="inline"><span class="w">getcflag</span></code>
</b>
<p>Retrieve the <code class="inline"><span class="w">c_cflag</span></code>
 field of a <code class="inline"><span class="w">termios</span></code>
 object.</p>
<pre class="verbatim"><ol><li>	<span class="i">$c_cflag</span> = <span class="i">$termios</span><span class="i">-&gt;getcflag</span><span class="sc">;</span></li></ol></pre></li>
<li><a name="getiflag"></a><b><code class="inline"><span class="w">getiflag</span></code>
</b>
<p>Retrieve the <code class="inline"><span class="w">c_iflag</span></code>
 field of a <code class="inline"><span class="w">termios</span></code>
 object.</p>
<pre class="verbatim"><ol><li>	<span class="i">$c_iflag</span> = <span class="i">$termios</span><span class="i">-&gt;getiflag</span><span class="sc">;</span></li></ol></pre></li>
<li><a name="getispeed"></a><b><code class="inline"><span class="w">getispeed</span></code>
</b>
<p>Retrieve the input baud rate.</p>
<pre class="verbatim"><ol><li>	<span class="i">$ispeed</span> = <span class="i">$termios</span><span class="i">-&gt;getispeed</span><span class="sc">;</span></li></ol></pre></li>
<li><a name="getlflag"></a><b><code class="inline"><span class="w">getlflag</span></code>
</b>
<p>Retrieve the <code class="inline"><span class="w">c_lflag</span></code>
 field of a <code class="inline"><span class="w">termios</span></code>
 object.</p>
<pre class="verbatim"><ol><li>	<span class="i">$c_lflag</span> = <span class="i">$termios</span><span class="i">-&gt;getlflag</span><span class="sc">;</span></li></ol></pre></li>
<li><a name="getoflag"></a><b><code class="inline"><span class="w">getoflag</span></code>
</b>
<p>Retrieve the <code class="inline"><span class="w">c_oflag</span></code>
 field of a <code class="inline"><span class="w">termios</span></code>
 object.</p>
<pre class="verbatim"><ol><li>	<span class="i">$c_oflag</span> = <span class="i">$termios</span><span class="i">-&gt;getoflag</span><span class="sc">;</span></li></ol></pre></li>
<li><a name="getospeed"></a><b><code class="inline"><span class="w">getospeed</span></code>
</b>
<p>Retrieve the output baud rate.</p>
<pre class="verbatim"><ol><li>	<span class="i">$ospeed</span> = <span class="i">$termios</span><span class="i">-&gt;getospeed</span><span class="sc">;</span></li></ol></pre></li>
<li><a name="setattr"></a><b><code class="inline"><span class="w">setattr</span></code>
</b>
<p>Set terminal control attributes.</p>
<p>Set attributes immediately for stdout.</p>
<pre class="verbatim"><ol><li>	<span class="i">$termios</span><span class="i">-&gt;setattr</span><span class="s">(</span> <span class="n">1</span><span class="cm">,</span> <span class="i">&amp;POSIX::TCSANOW</span> <span class="s">)</span><span class="sc">;</span></li></ol></pre><p>Returns <code class="inline"><a class="l_k" href="functions/undef.html">undef</a></code> on failure.</p>
</li>
<li><a name="setcc"></a><b><code class="inline"><span class="w">setcc</span></code>
</b>
<p>Set a value in the <code class="inline"><span class="w">c_cc</span></code>
 field of a <code class="inline"><span class="w">termios</span></code>
 object.  The <code class="inline"><span class="w">c_cc</span></code>
 field is an
array so an index must be specified.</p>
<pre class="verbatim"><ol><li>	<span class="i">$termios</span><span class="i">-&gt;setcc</span><span class="s">(</span> <span class="i">&amp;POSIX::VEOF</span><span class="cm">,</span> <span class="n">1</span> <span class="s">)</span><span class="sc">;</span></li></ol></pre></li>
<li><a name="setcflag"></a><b><code class="inline"><span class="w">setcflag</span></code>
</b>
<p>Set the <code class="inline"><span class="w">c_cflag</span></code>
 field of a <code class="inline"><span class="w">termios</span></code>
 object.</p>
<pre class="verbatim"><ol><li>	<span class="i">$termios</span><span class="i">-&gt;setcflag</span><span class="s">(</span> <span class="i">$c_cflag</span> | <span class="i">&amp;POSIX::CLOCAL</span> <span class="s">)</span><span class="sc">;</span></li></ol></pre></li>
<li><a name="setiflag"></a><b><code class="inline"><span class="w">setiflag</span></code>
</b>
<p>Set the <code class="inline"><span class="w">c_iflag</span></code>
 field of a <code class="inline"><span class="w">termios</span></code>
 object.</p>
<pre class="verbatim"><ol><li>	<span class="i">$termios</span><span class="i">-&gt;setiflag</span><span class="s">(</span> <span class="i">$c_iflag</span> | <span class="i">&amp;POSIX::BRKINT</span> <span class="s">)</span><span class="sc">;</span></li></ol></pre></li>
<li><a name="setispeed"></a><b><code class="inline"><span class="w">setispeed</span></code>
</b>
<p>Set the input baud rate.</p>
<pre class="verbatim"><ol><li>	<span class="i">$termios</span><span class="i">-&gt;setispeed</span><span class="s">(</span> <span class="i">&amp;POSIX::B9600</span> <span class="s">)</span><span class="sc">;</span></li></ol></pre><p>Returns <code class="inline"><a class="l_k" href="functions/undef.html">undef</a></code> on failure.</p>
</li>
<li><a name="setlflag"></a><b><code class="inline"><span class="w">setlflag</span></code>
</b>
<p>Set the <code class="inline"><span class="w">c_lflag</span></code>
 field of a <code class="inline"><span class="w">termios</span></code>
 object.</p>
<pre class="verbatim"><ol><li>	<span class="i">$termios</span><span class="i">-&gt;setlflag</span><span class="s">(</span> <span class="i">$c_lflag</span> | <span class="i">&amp;POSIX::ECHO</span> <span class="s">)</span><span class="sc">;</span></li></ol></pre></li>
<li><a name="setoflag"></a><b><code class="inline"><span class="w">setoflag</span></code>
</b>
<p>Set the <code class="inline"><span class="w">c_oflag</span></code>
 field of a <code class="inline"><span class="w">termios</span></code>
 object.</p>
<pre class="verbatim"><ol><li>	<span class="i">$termios</span><span class="i">-&gt;setoflag</span><span class="s">(</span> <span class="i">$c_oflag</span> | <span class="i">&amp;POSIX::OPOST</span> <span class="s">)</span><span class="sc">;</span></li></ol></pre></li>
<li><a name="setospeed"></a><b><code class="inline"><span class="w">setospeed</span></code>
</b>
<p>Set the output baud rate.</p>
<pre class="verbatim"><ol><li>	<span class="i">$termios</span><span class="i">-&gt;setospeed</span><span class="s">(</span> <span class="i">&amp;POSIX::B9600</span> <span class="s">)</span><span class="sc">;</span></li></ol></pre><p>Returns <code class="inline"><a class="l_k" href="functions/undef.html">undef</a></code> on failure.</p>
</li>
<li><a name="Baud-rate-values"></a><b>Baud rate values</b>
<p><code class="inline"><span class="w">B38400</span></code>
 <code class="inline"><span class="w">B75</span></code>
 <code class="inline"><span class="w">B200</span></code>
 <code class="inline"><span class="w">B134</span></code>
 <code class="inline"><span class="w">B300</span></code>
 <code class="inline"><span class="w">B1800</span></code>
 <code class="inline"><span class="w">B150</span></code>
 <code class="inline"><span class="w">B0</span></code>
 <code class="inline"><span class="w">B19200</span></code>
 <code class="inline"><span class="w">B1200</span></code>
 <code class="inline"><span class="w">B9600</span></code>
 <code class="inline"><span class="w">B600</span></code>
 <code class="inline"><span class="w">B4800</span></code>
 <code class="inline"><span class="w">B50</span></code>
 <code class="inline"><span class="w">B2400</span></code>
 <code class="inline"><span class="w">B110</span></code>
</p>
</li>
<li><a name="Terminal-interface-values"></a><b>Terminal interface values</b>
<p><code class="inline"><span class="w">TCSADRAIN</span></code>
 <code class="inline"><span class="w">TCSANOW</span></code>
 <code class="inline"><span class="w">TCOON</span></code>
 <code class="inline"><span class="w">TCIOFLUSH</span></code>
 <code class="inline"><span class="w">TCOFLUSH</span></code>
 <code class="inline"><span class="w">TCION</span></code>
 <code class="inline"><span class="w">TCIFLUSH</span></code>
 <code class="inline"><span class="w">TCSAFLUSH</span></code>
 <code class="inline"><span class="w">TCIOFF</span></code>
 <code class="inline"><span class="w">TCOOFF</span></code>
</p>
</li>
<li><a name="c_cc-field-values"></a><b><code class="inline"><span class="w">c_cc</span></code>
 field values</b>
<p><code class="inline"><span class="w">VEOF</span></code>
 <code class="inline"><span class="w">VEOL</span></code>
 <code class="inline"><span class="w">VERASE</span></code>
 <code class="inline"><span class="w">VINTR</span></code>
 <code class="inline"><span class="w">VKILL</span></code>
 <code class="inline"><span class="w">VQUIT</span></code>
 <code class="inline"><span class="w">VSUSP</span></code>
 <code class="inline"><span class="w">VSTART</span></code>
 <code class="inline"><span class="w">VSTOP</span></code>
 <code class="inline"><span class="w">VMIN</span></code>
 <code class="inline"><span class="w">VTIME</span></code>
 <code class="inline"><span class="w">NCCS</span></code>
</p>
</li>
<li><a name="c_cflag-field-values"></a><b><code class="inline"><span class="w">c_cflag</span></code>
 field values</b>
<p><code class="inline"><span class="w">CLOCAL</span></code>
 <code class="inline"><span class="w">CREAD</span></code>
 <code class="inline"><span class="w">CSIZE</span></code>
 <code class="inline"><span class="w">CS5</span></code>
 <code class="inline"><span class="w">CS6</span></code>
 <code class="inline"><span class="w">CS7</span></code>
 <code class="inline"><span class="w">CS8</span></code>
 <code class="inline"><span class="w">CSTOPB</span></code>
 <code class="inline"><span class="w">HUPCL</span></code>
 <code class="inline"><span class="w">PARENB</span></code>
 <code class="inline"><span class="w">PARODD</span></code>
</p>
</li>
<li><a name="c_iflag-field-values"></a><b><code class="inline"><span class="w">c_iflag</span></code>
 field values</b>
<p><code class="inline"><span class="w">BRKINT</span></code>
 <code class="inline"><span class="w">ICRNL</span></code>
 <code class="inline"><span class="w">IGNBRK</span></code>
 <code class="inline"><span class="w">IGNCR</span></code>
 <code class="inline"><span class="w">IGNPAR</span></code>
 <code class="inline"><span class="w">INLCR</span></code>
 <code class="inline"><span class="w">INPCK</span></code>
 <code class="inline"><span class="w">ISTRIP</span></code>
 <code class="inline"><span class="w">IXOFF</span></code>
 <code class="inline"><span class="w">IXON</span></code>
 <code class="inline"><span class="w">PARMRK</span></code>
</p>
</li>
<li><a name="c_lflag-field-values"></a><b><code class="inline"><span class="w">c_lflag</span></code>
 field values</b>
<p><code class="inline"><span class="w">ECHO</span></code>
 <code class="inline"><span class="w">ECHOE</span></code>
 <code class="inline"><span class="w">ECHOK</span></code>
 <code class="inline"><span class="w">ECHONL</span></code>
 <code class="inline"><span class="w">ICANON</span></code>
 <code class="inline"><span class="w">IEXTEN</span></code>
 <code class="inline"><span class="w">ISIG</span></code>
 <code class="inline"><span class="w">NOFLSH</span></code>
 <code class="inline"><span class="w">TOSTOP</span></code>
</p>
</li>
<li><a name="c_oflag-field-values"></a><b><code class="inline"><span class="w">c_oflag</span></code>
 field values</b>
<p><code class="inline"><span class="w">OPOST</span></code>
</p>
</li>
</ul>
<a name="PATHNAME-CONSTANTS"></a><h1>PATHNAME CONSTANTS</h1>
<ul>
<li><a name="Constants"></a><b>Constants</b>
<p><code class="inline"><span class="w">_PC_CHOWN_RESTRICTED</span></code>
 <code class="inline"><span class="w">_PC_LINK_MAX</span></code>
 <code class="inline"><span class="w">_PC_MAX_CANON</span></code>
 <code class="inline"><span class="w">_PC_MAX_INPUT</span></code>
 <code class="inline"><span class="w">_PC_NAME_MAX</span></code>

<code class="inline"><span class="w">_PC_NO_TRUNC</span></code>
 <code class="inline"><span class="w">_PC_PATH_MAX</span></code>
 <code class="inline"><span class="w">_PC_PIPE_BUF</span></code>
 <code class="inline"><span class="w">_PC_VDISABLE</span></code>
</p>
</li>
</ul>
<a name="POSIX-CONSTANTS"></a><h1>POSIX CONSTANTS</h1>
<ul>
<li><a name="Constants"></a><b>Constants</b>
<p><code class="inline"><span class="w">_POSIX_ARG_MAX</span></code>
 <code class="inline"><span class="w">_POSIX_CHILD_MAX</span></code>
 <code class="inline"><span class="w">_POSIX_CHOWN_RESTRICTED</span></code>
 <code class="inline"><span class="w">_POSIX_JOB_CONTROL</span></code>

<code class="inline"><span class="w">_POSIX_LINK_MAX</span></code>
 <code class="inline"><span class="w">_POSIX_MAX_CANON</span></code>
 <code class="inline"><span class="w">_POSIX_MAX_INPUT</span></code>
 <code class="inline"><span class="w">_POSIX_NAME_MAX</span></code>

<code class="inline"><span class="w">_POSIX_NGROUPS_MAX</span></code>
 <code class="inline"><span class="w">_POSIX_NO_TRUNC</span></code>
 <code class="inline"><span class="w">_POSIX_OPEN_MAX</span></code>
 <code class="inline"><span class="w">_POSIX_PATH_MAX</span></code>

<code class="inline"><span class="w">_POSIX_PIPE_BUF</span></code>
 <code class="inline"><span class="w">_POSIX_SAVED_IDS</span></code>
 <code class="inline"><span class="w">_POSIX_SSIZE_MAX</span></code>
 <code class="inline"><span class="w">_POSIX_STREAM_MAX</span></code>

<code class="inline"><span class="w">_POSIX_TZNAME_MAX</span></code>
 <code class="inline"><span class="w">_POSIX_VDISABLE</span></code>
 <code class="inline"><span class="w">_POSIX_VERSION</span></code>
</p>
</li>
</ul>
<a name="SYSTEM-CONFIGURATION"></a><h1>SYSTEM CONFIGURATION</h1>
<ul>
<li><a name="Constants"></a><b>Constants</b>
<p><code class="inline"><span class="w">_SC_ARG_MAX</span></code>
 <code class="inline"><span class="w">_SC_CHILD_MAX</span></code>
 <code class="inline"><span class="w">_SC_CLK_TCK</span></code>
 <code class="inline"><span class="w">_SC_JOB_CONTROL</span></code>
 <code class="inline"><span class="w">_SC_NGROUPS_MAX</span></code>

<code class="inline"><span class="w">_SC_OPEN_MAX</span></code>
 <code class="inline"><span class="w">_SC_PAGESIZE</span></code>
 <code class="inline"><span class="w">_SC_SAVED_IDS</span></code>
 <code class="inline"><span class="w">_SC_STREAM_MAX</span></code>
 <code class="inline"><span class="w">_SC_TZNAME_MAX</span></code>

<code class="inline"><span class="w">_SC_VERSION</span></code>
</p>
</li>
</ul>
<a name="ERRNO"></a><h1>ERRNO</h1>
<ul>
<li><a name="Constants"></a><b>Constants</b>
<p><code class="inline"><span class="w">E2BIG</span></code>
 <code class="inline"><span class="w">EACCES</span></code>
 <code class="inline"><span class="w">EADDRINUSE</span></code>
 <code class="inline"><span class="w">EADDRNOTAVAIL</span></code>
 <code class="inline"><span class="w">EAFNOSUPPORT</span></code>
 <code class="inline"><span class="w">EAGAIN</span></code>
 <code class="inline"><span class="w">EALREADY</span></code>
 <code class="inline"><span class="w">EBADF</span></code>
 <code class="inline"><span class="w">EBADMSG</span></code>

<code class="inline"><span class="w">EBUSY</span></code>
 <code class="inline"><span class="w">ECANCELED</span></code>
 <code class="inline"><span class="w">ECHILD</span></code>
 <code class="inline"><span class="w">ECONNABORTED</span></code>
 <code class="inline"><span class="w">ECONNREFUSED</span></code>
 <code class="inline"><span class="w">ECONNRESET</span></code>
 <code class="inline"><span class="w">EDEADLK</span></code>
 <code class="inline"><span class="w">EDESTADDRREQ</span></code>

<code class="inline"><span class="w">EDOM</span></code>
 <code class="inline"><span class="w">EDQUOT</span></code>
 <code class="inline"><span class="w">EEXIST</span></code>
 <code class="inline"><span class="w">EFAULT</span></code>
 <code class="inline"><span class="w">EFBIG</span></code>
 <code class="inline"><span class="w">EHOSTDOWN</span></code>
 <code class="inline"><span class="w">EHOSTUNREACH</span></code>
 <code class="inline"><span class="w">EIDRM</span></code>
 <code class="inline"><span class="w">EILSEQ</span></code>
 <code class="inline"><span class="w">EINPROGRESS</span></code>

<code class="inline"><span class="w">EINTR</span></code>
 <code class="inline"><span class="w">EINVAL</span></code>
 <code class="inline"><span class="w">EIO</span></code>
 <code class="inline"><span class="w">EISCONN</span></code>
 <code class="inline"><span class="w">EISDIR</span></code>
 <code class="inline"><span class="w">ELOOP</span></code>
 <code class="inline"><span class="w">EMFILE</span></code>
 <code class="inline"><span class="w">EMLINK</span></code>
 <code class="inline"><span class="w">EMSGSIZE</span></code>
 <code class="inline"><span class="w">ENAMETOOLONG</span></code>

<code class="inline"><span class="w">ENETDOWN</span></code>
 <code class="inline"><span class="w">ENETRESET</span></code>
 <code class="inline"><span class="w">ENETUNREACH</span></code>
 <code class="inline"><span class="w">ENFILE</span></code>
 <code class="inline"><span class="w">ENOBUFS</span></code>
 <code class="inline"><span class="w">ENODATA</span></code>
 <code class="inline"><span class="w">ENODEV</span></code>
 <code class="inline"><span class="w">ENOENT</span></code>
 <code class="inline"><span class="w">ENOEXEC</span></code>

<code class="inline"><span class="w">ENOLCK</span></code>
 <code class="inline"><span class="w">ENOLINK</span></code>
 <code class="inline"><span class="w">ENOMEM</span></code>
 <code class="inline"><span class="w">ENOMSG</span></code>
 <code class="inline"><span class="w">ENOPROTOOPT</span></code>
 <code class="inline"><span class="w">ENOSPC</span></code>
 <code class="inline"><span class="w">ENOSR</span></code>
 <code class="inline"><span class="w">ENOSTR</span></code>
 <code class="inline"><span class="w">ENOSYS</span></code>
 <code class="inline"><span class="w">ENOTBLK</span></code>

<code class="inline"><span class="w">ENOTCONN</span></code>
 <code class="inline"><span class="w">ENOTDIR</span></code>
 <code class="inline"><span class="w">ENOTEMPTY</span></code>
 <code class="inline"><span class="w">ENOTRECOVERABLE</span></code>
 <code class="inline"><span class="w">ENOTSOCK</span></code>
 <code class="inline"><span class="w">ENOTSUP</span></code>
 <code class="inline"><span class="w">ENOTTY</span></code>
 <code class="inline"><span class="w">ENXIO</span></code>

<code class="inline"><span class="w">EOPNOTSUPP</span></code>
 <code class="inline"><span class="w">EOTHER</span></code>
 <code class="inline"><span class="w">EOVERFLOW</span></code>
 <code class="inline"><span class="w">EOWNERDEAD</span></code>
 <code class="inline"><span class="w">EPERM</span></code>
 <code class="inline"><span class="w">EPFNOSUPPORT</span></code>
 <code class="inline"><span class="w">EPIPE</span></code>
 <code class="inline"><span class="w">EPROCLIM</span></code>
 <code class="inline"><span class="w">EPROTO</span></code>

<code class="inline"><span class="w">EPROTONOSUPPORT</span></code>
 <code class="inline"><span class="w">EPROTOTYPE</span></code>
 <code class="inline"><span class="w">ERANGE</span></code>
 <code class="inline"><span class="w">EREMOTE</span></code>
 <code class="inline"><span class="w">ERESTART</span></code>
 <code class="inline"><span class="w">EROFS</span></code>
 <code class="inline"><span class="w">ESHUTDOWN</span></code>

<code class="inline"><span class="w">ESOCKTNOSUPPORT</span></code>
 <code class="inline"><span class="w">ESPIPE</span></code>
 <code class="inline"><span class="w">ESRCH</span></code>
 <code class="inline"><span class="w">ESTALE</span></code>
 <code class="inline"><span class="w">ETIME</span></code>
 <code class="inline"><span class="w">ETIMEDOUT</span></code>
 <code class="inline"><span class="w">ETOOMANYREFS</span></code>
 <code class="inline"><span class="w">ETXTBSY</span></code>
 <code class="inline"><span class="w">EUSERS</span></code>

<code class="inline"><span class="w">EWOULDBLOCK</span></code>
 <code class="inline"><span class="w">EXDEV</span></code>
</p>
</li>
</ul>
<a name="FCNTL"></a><h1>FCNTL</h1>
<ul>
<li><a name="Constants"></a><b>Constants</b>
<p><code class="inline"><span class="w">FD_CLOEXEC</span></code>
 <code class="inline"><span class="w">F_DUPFD</span></code>
 <code class="inline"><span class="w">F_GETFD</span></code>
 <code class="inline"><span class="w">F_GETFL</span></code>
 <code class="inline"><span class="w">F_GETLK</span></code>
 <code class="inline"><span class="w">F_OK</span></code>
 <code class="inline"><span class="w">F_RDLCK</span></code>
 <code class="inline"><span class="w">F_SETFD</span></code>
 <code class="inline"><span class="w">F_SETFL</span></code>
 <code class="inline"><span class="w">F_SETLK</span></code>

<code class="inline"><span class="w">F_SETLKW</span></code>
 <code class="inline"><span class="w">F_UNLCK</span></code>
 <code class="inline"><span class="w">F_WRLCK</span></code>
 <code class="inline"><span class="w">O_ACCMODE</span></code>
 <code class="inline"><span class="w">O_APPEND</span></code>
 <code class="inline"><span class="w">O_CREAT</span></code>
 <code class="inline"><span class="w">O_EXCL</span></code>
 <code class="inline"><span class="w">O_NOCTTY</span></code>
 <code class="inline"><span class="w">O_NONBLOCK</span></code>

<code class="inline"><span class="w">O_RDONLY</span></code>
 <code class="inline"><span class="w">O_RDWR</span></code>
 <code class="inline"><span class="w">O_TRUNC</span></code>
 <code class="inline"><span class="w">O_WRONLY</span></code>
</p>
</li>
</ul>
<a name="FLOAT"></a><h1>FLOAT</h1>
<ul>
<li><a name="Constants"></a><b>Constants</b>
<p><code class="inline"><span class="w">DBL_DIG</span></code>
 <code class="inline"><span class="w">DBL_EPSILON</span></code>
 <code class="inline"><span class="w">DBL_MANT_DIG</span></code>
 <code class="inline"><span class="w">DBL_MAX</span></code>
 <code class="inline"><span class="w">DBL_MAX_10_EXP</span></code>
 <code class="inline"><span class="w">DBL_MAX_EXP</span></code>
 <code class="inline"><span class="w">DBL_MIN</span></code>

<code class="inline"><span class="w">DBL_MIN_10_EXP</span></code>
 <code class="inline"><span class="w">DBL_MIN_EXP</span></code>
 <code class="inline"><span class="w">FLT_DIG</span></code>
 <code class="inline"><span class="w">FLT_EPSILON</span></code>
 <code class="inline"><span class="w">FLT_MANT_DIG</span></code>
 <code class="inline"><span class="w">FLT_MAX</span></code>

<code class="inline"><span class="w">FLT_MAX_10_EXP</span></code>
 <code class="inline"><span class="w">FLT_MAX_EXP</span></code>
 <code class="inline"><span class="w">FLT_MIN</span></code>
 <code class="inline"><span class="w">FLT_MIN_10_EXP</span></code>
 <code class="inline"><span class="w">FLT_MIN_EXP</span></code>
 <code class="inline"><span class="w">FLT_RADIX</span></code>

<code class="inline"><span class="w">FLT_ROUNDS</span></code>
 <code class="inline"><span class="w">LDBL_DIG</span></code>
 <code class="inline"><span class="w">LDBL_EPSILON</span></code>
 <code class="inline"><span class="w">LDBL_MANT_DIG</span></code>
 <code class="inline"><span class="w">LDBL_MAX</span></code>
 <code class="inline"><span class="w">LDBL_MAX_10_EXP</span></code>

<code class="inline"><span class="w">LDBL_MAX_EXP</span></code>
 <code class="inline"><span class="w">LDBL_MIN</span></code>
 <code class="inline"><span class="w">LDBL_MIN_10_EXP</span></code>
 <code class="inline"><span class="w">LDBL_MIN_EXP</span></code>
</p>
</li>
</ul>
<a name="FLOATING-POINT-ENVIRONMENT"></a><h1>FLOATING-POINT ENVIRONMENT</h1>
<ul>
<li><a name="Constants"></a><b>Constants</b>
<p><code class="inline"><span class="w">FE_DOWNWARD</span></code>
 <code class="inline"><span class="w">FE_TONEAREST</span></code>
 <code class="inline"><span class="w">FE_TOWARDZERO</span></code>
 <code class="inline"><span class="w">FE_UPWARD</span></code>

on systems that support them.</p>
</li>
</ul>
<a name="LIMITS"></a><h1>LIMITS</h1>
<ul>
<li><a name="Constants"></a><b>Constants</b>
<p><code class="inline"><span class="w">ARG_MAX</span></code>
 <code class="inline"><span class="w">CHAR_BIT</span></code>
 <code class="inline"><span class="w">CHAR_MAX</span></code>
 <code class="inline"><span class="w">CHAR_MIN</span></code>
 <code class="inline"><span class="w">CHILD_MAX</span></code>
 <code class="inline"><span class="w">INT_MAX</span></code>
 <code class="inline"><span class="w">INT_MIN</span></code>
 <code class="inline"><span class="w">LINK_MAX</span></code>
 <code class="inline"><span class="w">LONG_MAX</span></code>

<code class="inline"><span class="w">LONG_MIN</span></code>
 <code class="inline"><span class="w">MAX_CANON</span></code>
 <code class="inline"><span class="w">MAX_INPUT</span></code>
 <code class="inline"><span class="w">MB_LEN_MAX</span></code>
 <code class="inline"><span class="w">NAME_MAX</span></code>
 <code class="inline"><span class="w">NGROUPS_MAX</span></code>
 <code class="inline"><span class="w">OPEN_MAX</span></code>
 <code class="inline"><span class="w">PATH_MAX</span></code>

<code class="inline"><span class="w">PIPE_BUF</span></code>
 <code class="inline"><span class="w">SCHAR_MAX</span></code>
 <code class="inline"><span class="w">SCHAR_MIN</span></code>
 <code class="inline"><span class="w">SHRT_MAX</span></code>
 <code class="inline"><span class="w">SHRT_MIN</span></code>
 <code class="inline"><span class="w">SSIZE_MAX</span></code>
 <code class="inline"><span class="w">STREAM_MAX</span></code>
 <code class="inline"><span class="w">TZNAME_MAX</span></code>

<code class="inline"><span class="w">UCHAR_MAX</span></code>
 <code class="inline"><span class="w">UINT_MAX</span></code>
 <code class="inline"><span class="w">ULONG_MAX</span></code>
 <code class="inline"><span class="w">USHRT_MAX</span></code>
</p>
</li>
</ul>
<a name="LOCALE"></a><h1>LOCALE</h1>
<ul>
<li><a name="Constants"></a><b>Constants</b>
<p><code class="inline"><span class="w">LC_ALL</span></code>
 <code class="inline"><span class="w">LC_COLLATE</span></code>
 <code class="inline"><span class="w">LC_CTYPE</span></code>
 <code class="inline"><span class="w">LC_MONETARY</span></code>
 <code class="inline"><span class="w">LC_NUMERIC</span></code>
 <code class="inline"><span class="w">LC_TIME</span></code>
 <code class="inline"><span class="w">LC_MESSAGES</span></code>

on systems that support them.</p>
</li>
</ul>
<a name="MATH"></a><h1>MATH</h1>
<ul>
<li><a name="Constants"></a><b>Constants</b>
<p><code class="inline"><span class="w">HUGE_VAL</span></code>
</p>
<p><code class="inline"><span class="w">FP_ILOGB0</span></code>
 <code class="inline"><span class="w">FP_ILOGBNAN</span></code>
 <code class="inline"><span class="w">FP_INFINITE</span></code>
 <code class="inline"><span class="w">FP_NAN</span></code>
 <code class="inline"><span class="w">FP_NORMAL</span></code>
 <code class="inline"><span class="w">FP_SUBNORMAL</span></code>
 <code class="inline"><span class="w">FP_ZERO</span></code>

<code class="inline"><span class="w">INFINITY</span></code>
 <code class="inline"><span class="w">NAN</span></code>
 <code class="inline"><span class="w">Inf</span></code>
 <code class="inline"><span class="w">NaN</span></code>

<code class="inline"><span class="w">M_1_PI</span></code>
 <code class="inline"><span class="w">M_2_PI</span></code>
 <code class="inline"><span class="w">M_2_SQRTPI</span></code>
 <code class="inline"><span class="w">M_E</span></code>
 <code class="inline"><span class="w">M_LN10</span></code>
 <code class="inline"><span class="w">M_LN2</span></code>
 <code class="inline"><span class="w">M_LOG10E</span></code>
 <code class="inline"><span class="w">M_LOG2E</span></code>
 <code class="inline"><span class="w">M_PI</span></code>

<code class="inline"><span class="w">M_PI_2</span></code>
 <code class="inline"><span class="w">M_PI_4</span></code>
 <code class="inline"><span class="w">M_SQRT1_2</span></code>
 <code class="inline"><span class="w">M_SQRT2</span></code>

on systems with C99 support.</p>
</li>
</ul>
<a name="SIGNAL"></a><h1>SIGNAL</h1>
<ul>
<li><a name="Constants"></a><b>Constants</b>
<p><code class="inline"><span class="w">SA_NOCLDSTOP</span></code>
 <code class="inline"><span class="w">SA_NOCLDWAIT</span></code>
 <code class="inline"><span class="w">SA_NODEFER</span></code>
 <code class="inline"><span class="w">SA_ONSTACK</span></code>
 <code class="inline"><span class="w">SA_RESETHAND</span></code>
 <code class="inline"><span class="w">SA_RESTART</span></code>

<code class="inline"><span class="w">SA_SIGINFO</span></code>
 <code class="inline"><span class="w">SIGABRT</span></code>
 <code class="inline"><span class="w">SIGALRM</span></code>
 <code class="inline"><span class="w">SIGCHLD</span></code>
 <code class="inline"><span class="w">SIGCONT</span></code>
 <code class="inline"><span class="w">SIGFPE</span></code>
 <code class="inline"><span class="w">SIGHUP</span></code>
 <code class="inline"><span class="w">SIGILL</span></code>
 <code class="inline"><span class="w">SIGINT</span></code>

<code class="inline"><span class="w">SIGKILL</span></code>
 <code class="inline"><span class="w">SIGPIPE</span></code>
 <code class="inline"><span class="w">SIGQUIT</span></code>
 <code class="inline"><span class="w">SIGSEGV</span></code>
 <code class="inline"><span class="w">SIGSTOP</span></code>
 <code class="inline"><span class="w">SIGTERM</span></code>
 <code class="inline"><span class="w">SIGTSTP</span></code>
 <code class="inline"><span class="w">SIGTTIN</span></code>
 <code class="inline"><span class="w">SIGTTOU</span></code>

<code class="inline"><span class="w">SIGUSR1</span></code>
 <code class="inline"><span class="w">SIGUSR2</span></code>
 <code class="inline"><span class="w">SIG_BLOCK</span></code>
 <code class="inline"><span class="w">SIG_DFL</span></code>
 <code class="inline"><span class="w">SIG_ERR</span></code>
 <code class="inline"><span class="w">SIG_IGN</span></code>
 <code class="inline"><span class="w">SIG_SETMASK</span></code>

<code class="inline"><span class="w">SIG_UNBLOCK</span></code>

<code class="inline"><span class="w">ILL_ILLOPC</span></code>
 <code class="inline"><span class="w">ILL_ILLOPN</span></code>
 <code class="inline"><span class="w">ILL_ILLADR</span></code>
 <code class="inline"><span class="w">ILL_ILLTRP</span></code>
 <code class="inline"><span class="w">ILL_PRVOPC</span></code>
 <code class="inline"><span class="w">ILL_PRVREG</span></code>
 <code class="inline"><span class="w">ILL_COPROC</span></code>

<code class="inline"><span class="w">ILL_BADSTK</span></code>
 <code class="inline"><span class="w">FPE_INTDIV</span></code>
 <code class="inline"><span class="w">FPE_INTOVF</span></code>
 <code class="inline"><span class="w">FPE_FLTDIV</span></code>
 <code class="inline"><span class="w">FPE_FLTOVF</span></code>
 <code class="inline"><span class="w">FPE_FLTUND</span></code>
 <code class="inline"><span class="w">FPE_FLTRES</span></code>

<code class="inline"><span class="w">FPE_FLTINV</span></code>
 <code class="inline"><span class="w">FPE_FLTSUB</span></code>
 <code class="inline"><span class="w">SEGV_MAPERR</span></code>
 <code class="inline"><span class="w">SEGV_ACCERR</span></code>
 <code class="inline"><span class="w">BUS_ADRALN</span></code>
 <code class="inline"><span class="w">BUS_ADRERR</span></code>

<code class="inline"><span class="w">BUS_OBJERR</span></code>
 <code class="inline"><span class="w">TRAP_BRKPT</span></code>
 <code class="inline"><span class="w">TRAP_TRACE</span></code>
 <code class="inline"><span class="w">CLD_EXITED</span></code>
 <code class="inline"><span class="w">CLD_KILLED</span></code>
 <code class="inline"><span class="w">CLD_DUMPED</span></code>
 <code class="inline"><span class="w">CLD_TRAPPED</span></code>

<code class="inline"><span class="w">CLD_STOPPED</span></code>
 <code class="inline"><span class="w">CLD_CONTINUED</span></code>
 <code class="inline"><span class="w">POLL_IN</span></code>
 <code class="inline"><span class="w">POLL_OUT</span></code>
 <code class="inline"><span class="w">POLL_MSG</span></code>
 <code class="inline"><span class="w">POLL_ERR</span></code>
 <code class="inline"><span class="w">POLL_PRI</span></code>

<code class="inline"><span class="w">POLL_HUP</span></code>
 <code class="inline"><span class="w">SI_USER</span></code>
 <code class="inline"><span class="w">SI_QUEUE</span></code>
 <code class="inline"><span class="w">SI_TIMER</span></code>
 <code class="inline"><span class="w">SI_ASYNCIO</span></code>
 <code class="inline"><span class="w">SI_MESGQ</span></code>
</p>
</li>
</ul>
<a name="STAT"></a><h1>STAT</h1>
<ul>
<li><a name="Constants"></a><b>Constants</b>
<p><code class="inline"><span class="w">S_IRGRP</span></code>
 <code class="inline"><span class="w">S_IROTH</span></code>
 <code class="inline"><span class="w">S_IRUSR</span></code>
 <code class="inline"><span class="w">S_IRWXG</span></code>
 <code class="inline"><span class="w">S_IRWXO</span></code>
 <code class="inline"><span class="w">S_IRWXU</span></code>
 <code class="inline"><span class="w">S_ISGID</span></code>
 <code class="inline"><span class="w">S_ISUID</span></code>
 <code class="inline"><span class="w">S_IWGRP</span></code>
 <code class="inline"><span class="w">S_IWOTH</span></code>

<code class="inline"><span class="w">S_IWUSR</span></code>
 <code class="inline"><span class="w">S_IXGRP</span></code>
 <code class="inline"><span class="w">S_IXOTH</span></code>
 <code class="inline"><span class="w">S_IXUSR</span></code>
</p>
</li>
<li><a name="Macros"></a><b>Macros</b>
<p><code class="inline"><span class="w">S_ISBLK</span></code>
 <code class="inline"><span class="w">S_ISCHR</span></code>
 <code class="inline"><span class="w">S_ISDIR</span></code>
 <code class="inline"><span class="w">S_ISFIFO</span></code>
 <code class="inline"><span class="w">S_ISREG</span></code>
</p>
</li>
</ul>
<a name="STDLIB"></a><h1>STDLIB</h1>
<ul>
<li><a name="Constants"></a><b>Constants</b>
<p><code class="inline"><span class="w">EXIT_FAILURE</span></code>
 <code class="inline"><span class="w">EXIT_SUCCESS</span></code>
 <code class="inline"><span class="w">MB_CUR_MAX</span></code>
 <code class="inline"><span class="w">RAND_MAX</span></code>
</p>
</li>
</ul>
<a name="STDIO"></a><h1>STDIO</h1>
<ul>
<li><a name="Constants"></a><b>Constants</b>
<p><code class="inline"><span class="w">BUFSIZ</span></code>
 <code class="inline"><span class="w">EOF</span></code>
 <code class="inline"><span class="w">FILENAME_MAX</span></code>
 <code class="inline"><span class="w">L_ctermid</span></code>
 <code class="inline"><span class="w">L_cuserid</span></code>
 <code class="inline"><span class="w">TMP_MAX</span></code>
</p>
</li>
</ul>
<a name="TIME"></a><h1>TIME</h1>
<ul>
<li><a name="Constants"></a><b>Constants</b>
<p><code class="inline"><span class="w">CLK_TCK</span></code>
 <code class="inline"><span class="w">CLOCKS_PER_SEC</span></code>
</p>
</li>
</ul>
<a name="UNISTD"></a><h1>UNISTD</h1>
<ul>
<li><a name="Constants"></a><b>Constants</b>
<p><code class="inline"><span class="w">R_OK</span></code>
 <code class="inline"><span class="w">SEEK_CUR</span></code>
 <code class="inline"><span class="w">SEEK_END</span></code>
 <code class="inline"><span class="w">SEEK_SET</span></code>
 <code class="inline"><span class="w">STDIN_FILENO</span></code>
 <code class="inline"><span class="w">STDOUT_FILENO</span></code>
 <code class="inline"><span class="w">STDERR_FILENO</span></code>
 <code class="inline"><span class="w">W_OK</span></code>
 <code class="inline"><span class="w">X_OK</span></code>
</p>
</li>
</ul>
<a name="WAIT"></a><h1>WAIT</h1>
<ul>
<li><a name="Constants"></a><b>Constants</b>
<p><code class="inline"><span class="w">WNOHANG</span></code>
 <code class="inline"><span class="w">WUNTRACED</span></code>
</p>
<ul>
<li><a name="WNOHANG"></a><b><code class="inline"><span class="w">WNOHANG</span></code>
</b>
<p>Do not suspend the calling process until a child process
changes state but instead return immediately.</p>
</li>
<li><a name="WUNTRACED"></a><b><code class="inline"><span class="w">WUNTRACED</span></code>
</b>
<p>Catch stopped child processes.</p>
</li>
</ul>
</li>
<li><a name="Macros"></a><b>Macros</b>
<p><code class="inline"><span class="w">WIFEXITED</span></code>
 <code class="inline"><span class="w">WEXITSTATUS</span></code>
 <code class="inline"><span class="w">WIFSIGNALED</span></code>
 <code class="inline"><span class="w">WTERMSIG</span></code>
 <code class="inline"><span class="w">WIFSTOPPED</span></code>
 <code class="inline"><span class="w">WSTOPSIG</span></code>
</p>
<ul>
<li><a name="WIFEXITED"></a><b><code class="inline"><span class="w">WIFEXITED</span></code>
</b>
<p><code class="inline"><span class="i">WIFEXITED</span><span class="s">(</span><span class="i">$</span>{<span class="w">^CHILD_ERROR_NATIVE</span>}<span class="s">)</span></code>
 returns true if the child process
exited normally (<code class="inline"><a class="l_k" href="functions/exit.html">exit()</a></code> or by falling off the end of <code class="inline"><span class="i">main</span><span class="s">(</span><span class="s">)</span></code>
)</p>
</li>
<li><a name="WEXITSTATUS"></a><b><code class="inline"><span class="w">WEXITSTATUS</span></code>
</b>
<p><code class="inline"><span class="i">WEXITSTATUS</span><span class="s">(</span><span class="i">$</span>{<span class="w">^CHILD_ERROR_NATIVE</span>}<span class="s">)</span></code>
 returns the normal exit status of
the child process (only meaningful if <code class="inline"><span class="i">WIFEXITED</span><span class="s">(</span><span class="i">$</span>{<span class="w">^CHILD_ERROR_NATIVE</span>}<span class="s">)</span></code>

is true)</p>
</li>
<li><a name="WIFSIGNALED"></a><b><code class="inline"><span class="w">WIFSIGNALED</span></code>
</b>
<p><code class="inline"><span class="i">WIFSIGNALED</span><span class="s">(</span><span class="i">$</span>{<span class="w">^CHILD_ERROR_NATIVE</span>}<span class="s">)</span></code>
 returns true if the child process
terminated because of a signal</p>
</li>
<li><a name="WTERMSIG"></a><b><code class="inline"><span class="w">WTERMSIG</span></code>
</b>
<p><code class="inline"><span class="i">WTERMSIG</span><span class="s">(</span><span class="i">$</span>{<span class="w">^CHILD_ERROR_NATIVE</span>}<span class="s">)</span></code>
 returns the signal the child process
terminated for (only meaningful if
<code class="inline"><span class="i">WIFSIGNALED</span><span class="s">(</span><span class="i">$</span>{<span class="w">^CHILD_ERROR_NATIVE</span>}<span class="s">)</span></code>

is true)</p>
</li>
<li><a name="WIFSTOPPED"></a><b><code class="inline"><span class="w">WIFSTOPPED</span></code>
</b>
<p><code class="inline"><span class="i">WIFSTOPPED</span><span class="s">(</span><span class="i">$</span>{<span class="w">^CHILD_ERROR_NATIVE</span>}<span class="s">)</span></code>
 returns true if the child process is
currently stopped (can happen only if you specified the WUNTRACED flag
to <code class="inline"><a class="l_k" href="functions/waitpid.html">waitpid()</a></code>)</p>
</li>
<li><a name="WSTOPSIG"></a><b><code class="inline"><span class="w">WSTOPSIG</span></code>
</b>
<p><code class="inline"><span class="i">WSTOPSIG</span><span class="s">(</span><span class="i">$</span>{<span class="w">^CHILD_ERROR_NATIVE</span>}<span class="s">)</span></code>
 returns the signal the child process
was stopped for (only meaningful if
<code class="inline"><span class="i">WIFSTOPPED</span><span class="s">(</span><span class="i">$</span>{<span class="w">^CHILD_ERROR_NATIVE</span>}<span class="s">)</span></code>

is true)</p>
</li>
</ul>
</li>
</ul>
<a name="WINSOCK"></a><h1>WINSOCK</h1>
<p>(Windows only.)</p>
<ul>
<li><a name="Constants"></a><b>Constants</b>
<p><code class="inline"><span class="w">WSAEINTR</span></code>
 <code class="inline"><span class="w">WSAEBADF</span></code>
 <code class="inline"><span class="w">WSAEACCES</span></code>
 <code class="inline"><span class="w">WSAEFAULT</span></code>
 <code class="inline"><span class="w">WSAEINVAL</span></code>
 <code class="inline"><span class="w">WSAEMFILE</span></code>
 <code class="inline"><span class="w">WSAEWOULDBLOCK</span></code>

<code class="inline"><span class="w">WSAEINPROGRESS</span></code>
 <code class="inline"><span class="w">WSAEALREADY</span></code>
 <code class="inline"><span class="w">WSAENOTSOCK</span></code>
 <code class="inline"><span class="w">WSAEDESTADDRREQ</span></code>
 <code class="inline"><span class="w">WSAEMSGSIZE</span></code>

<code class="inline"><span class="w">WSAEPROTOTYPE</span></code>
 <code class="inline"><span class="w">WSAENOPROTOOPT</span></code>
 <code class="inline"><span class="w">WSAEPROTONOSUPPORT</span></code>
 <code class="inline"><span class="w">WSAESOCKTNOSUPPORT</span></code>

<code class="inline"><span class="w">WSAEOPNOTSUPP</span></code>
 <code class="inline"><span class="w">WSAEPFNOSUPPORT</span></code>
 <code class="inline"><span class="w">WSAEAFNOSUPPORT</span></code>
 <code class="inline"><span class="w">WSAEADDRINUSE</span></code>

<code class="inline"><span class="w">WSAEADDRNOTAVAIL</span></code>
 <code class="inline"><span class="w">WSAENETDOWN</span></code>
 <code class="inline"><span class="w">WSAENETUNREACH</span></code>
 <code class="inline"><span class="w">WSAENETRESET</span></code>
 <code class="inline"><span class="w">WSAECONNABORTED</span></code>

<code class="inline"><span class="w">WSAECONNRESET</span></code>
 <code class="inline"><span class="w">WSAENOBUFS</span></code>
 <code class="inline"><span class="w">WSAEISCONN</span></code>
 <code class="inline"><span class="w">WSAENOTCONN</span></code>
 <code class="inline"><span class="w">WSAESHUTDOWN</span></code>

<code class="inline"><span class="w">WSAETOOMANYREFS</span></code>
 <code class="inline"><span class="w">WSAETIMEDOUT</span></code>
 <code class="inline"><span class="w">WSAECONNREFUSED</span></code>
 <code class="inline"><span class="w">WSAELOOP</span></code>
 <code class="inline"><span class="w">WSAENAMETOOLONG</span></code>

<code class="inline"><span class="w">WSAEHOSTDOWN</span></code>
 <code class="inline"><span class="w">WSAEHOSTUNREACH</span></code>
 <code class="inline"><span class="w">WSAENOTEMPTY</span></code>
 <code class="inline"><span class="w">WSAEPROCLIM</span></code>
 <code class="inline"><span class="w">WSAEUSERS</span></code>

<code class="inline"><span class="w">WSAEDQUOT</span></code>
 <code class="inline"><span class="w">WSAESTALE</span></code>
 <code class="inline"><span class="w">WSAEREMOTE</span></code>
 <code class="inline"><span class="w">WSAEDISCON</span></code>
 <code class="inline"><span class="w">WSAENOMORE</span></code>
 <code class="inline"><span class="w">WSAECANCELLED</span></code>

<code class="inline"><span class="w">WSAEINVALIDPROCTABLE</span></code>
 <code class="inline"><span class="w">WSAEINVALIDPROVIDER</span></code>
 <code class="inline"><span class="w">WSAEPROVIDERFAILEDINIT</span></code>

<code class="inline"><span class="w">WSAEREFUSED</span></code>
</p>
</li>
</ul>




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