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|
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"/>
<head>
<title>Lua-System docs</title>
<link rel="stylesheet" href="../ldoc.css" type="text/css" />
</head>
<body>
<div id="container">
<div id="product">
<div id="product_logo"></div>
<div id="product_name"><big><b></b></big></div>
<div id="product_description"></div>
</div> <!-- id="product" -->
<div id="main">
<!-- Menu -->
<div id="navigation">
<br/>
<h1>Lua-System</h1>
<ul>
<li><a href="../index.html">Index</a></li>
</ul>
<h2>Contents</h2>
<ul>
<li><a href="#Fields">Fields</a></li>
<li><a href="#Environment">Environment </a></li>
<li><a href="#Random">Random </a></li>
<li><a href="#Terminal">Terminal </a></li>
<li><a href="#Time">Time </a></li>
</ul>
<h2>Modules</h2>
<ul class="nowrap">
<li><strong>system</strong></li>
</ul>
<h2>Classes</h2>
<ul class="nowrap">
<li><a href="../classes/bitflags.html">bitflags</a></li>
</ul>
<h2>Topics</h2>
<ul class="">
<li><a href="../topics/01-introduction.md.html">1. Introduction</a></li>
<li><a href="../topics/02-development.md.html">2. Development</a></li>
<li><a href="../topics/03-terminal.md.html">3. Terminal functionality</a></li>
<li><a href="../topics/CHANGELOG.md.html">CHANGELOG</a></li>
<li><a href="../topics/LICENSE.md.html">MIT License</a></li>
</ul>
<h2>Examples</h2>
<ul class="nowrap">
<li><a href="../examples/compat.lua.html">compat.lua</a></li>
<li><a href="../examples/flag_debugging.lua.html">flag_debugging.lua</a></li>
<li><a href="../examples/password_input.lua.html">password_input.lua</a></li>
<li><a href="../examples/read.lua.html">read.lua</a></li>
<li><a href="../examples/readline.lua.html">readline.lua</a></li>
<li><a href="../examples/spinner.lua.html">spinner.lua</a></li>
<li><a href="../examples/spiral_snake.lua.html">spiral_snake.lua</a></li>
<li><a href="../examples/terminalsize.lua.html">terminalsize.lua</a></li>
</ul>
</div>
<div id="content">
<h1>Module <code>system</code></h1>
<p>Platform independent system calls for Lua.</p>
<p>
</p>
<h2><a href="#Fields">Fields</a></h2>
<table class="function_list">
<tr>
<td class="name" nowrap><a href="#windows">windows</a></td>
<td class="summary">Flag to identify Windows.</td>
</tr>
</table>
<h2><a href="#Environment">Environment </a></h2>
<table class="function_list">
<tr>
<td class="name" nowrap><a href="#getenv">getenv (name)</a></td>
<td class="summary">Gets the value of an environment variable.</td>
</tr>
<tr>
<td class="name" nowrap><a href="#getenvs">getenvs ()</a></td>
<td class="summary">Returns a table with all environment variables.</td>
</tr>
<tr>
<td class="name" nowrap><a href="#setenv">setenv (name[, value])</a></td>
<td class="summary">Sets an environment variable.</td>
</tr>
</table>
<h2><a href="#Random">Random </a></h2>
<table class="function_list">
<tr>
<td class="name" nowrap><a href="#random">random ([length=1])</a></td>
<td class="summary">Generate random bytes.</td>
</tr>
</table>
<h2><a href="#Terminal">Terminal </a></h2>
<table class="function_list">
<tr>
<td class="name" nowrap><a href="#CODEPAGE_UTF8">CODEPAGE_UTF8</a></td>
<td class="summary">UTF8 codepage.</td>
</tr>
<tr>
<td class="name" nowrap><a href="#_readkey">_readkey ()</a></td>
<td class="summary">Reads a key from the console non-blocking.</td>
</tr>
<tr>
<td class="name" nowrap><a href="#autotermrestore">autotermrestore ()</a></td>
<td class="summary">Backs up terminal settings and restores them on application exit.</td>
</tr>
<tr>
<td class="name" nowrap><a href="#getconsolecp">getconsolecp ()</a></td>
<td class="summary">Gets the current console code page (Windows).</td>
</tr>
<tr>
<td class="name" nowrap><a href="#getconsoleflags">getconsoleflags (file)</a></td>
<td class="summary">Gets console flags (Windows).</td>
</tr>
<tr>
<td class="name" nowrap><a href="#getconsoleoutputcp">getconsoleoutputcp ()</a></td>
<td class="summary">Gets the current console output code page (Windows).</td>
</tr>
<tr>
<td class="name" nowrap><a href="#getnonblock">getnonblock (fd)</a></td>
<td class="summary">Gets non-blocking mode status for a file (Posix).</td>
</tr>
<tr>
<td class="name" nowrap><a href="#isatty">isatty (file)</a></td>
<td class="summary">Checks if a file-handle is a TTY.</td>
</tr>
<tr>
<td class="name" nowrap><a href="#listconsoleflags">listconsoleflags (fh)</a></td>
<td class="summary">Debug function for console flags (Windows).</td>
</tr>
<tr>
<td class="name" nowrap><a href="#listtermflags">listtermflags (fh)</a></td>
<td class="summary">Debug function for terminal flags (Posix).</td>
</tr>
<tr>
<td class="name" nowrap><a href="#readansi">readansi (timeout)</a></td>
<td class="summary">Reads a single key, if it is the start of ansi escape sequence then it reads
the full sequence.</td>
</tr>
<tr>
<td class="name" nowrap><a href="#readkey">readkey (timeout)</a></td>
<td class="summary">Reads a single byte from the console, with a timeout.</td>
</tr>
<tr>
<td class="name" nowrap><a href="#setconsolecp">setconsolecp (cp)</a></td>
<td class="summary">Sets the current console code page (Windows).</td>
</tr>
<tr>
<td class="name" nowrap><a href="#setconsoleflags">setconsoleflags (file, bitflags)</a></td>
<td class="summary">Sets the console flags (Windows).</td>
</tr>
<tr>
<td class="name" nowrap><a href="#setconsoleoutputcp">setconsoleoutputcp (cp)</a></td>
<td class="summary">Sets the current console output code page (Windows).</td>
</tr>
<tr>
<td class="name" nowrap><a href="#setnonblock">setnonblock (fd, make_non_block)</a></td>
<td class="summary">Enables or disables non-blocking mode for a file (Posix).</td>
</tr>
<tr>
<td class="name" nowrap><a href="#tcgetattr">tcgetattr (fd)</a></td>
<td class="summary">Get termios state (Posix).</td>
</tr>
<tr>
<td class="name" nowrap><a href="#tcsetattr">tcsetattr (fd, actions, termios)</a></td>
<td class="summary">Set termios state (Posix).</td>
</tr>
<tr>
<td class="name" nowrap><a href="#termbackup">termbackup ()</a></td>
<td class="summary">Returns a backup of terminal settings for stdin/out/err.</td>
</tr>
<tr>
<td class="name" nowrap><a href="#termrestore">termrestore (backup)</a></td>
<td class="summary">Restores terminal settings from a backup</td>
</tr>
<tr>
<td class="name" nowrap><a href="#termsize">termsize ()</a></td>
<td class="summary">Get the size of the terminal in rows and columns.</td>
</tr>
<tr>
<td class="name" nowrap><a href="#termwrap">termwrap (f)</a></td>
<td class="summary">Wraps a function to automatically restore terminal settings upon returning.</td>
</tr>
<tr>
<td class="name" nowrap><a href="#utf8cwidth">utf8cwidth (utf8_char)</a></td>
<td class="summary">Get the width of a utf8 character for terminal display.</td>
</tr>
<tr>
<td class="name" nowrap><a href="#utf8swidth">utf8swidth (utf8_string)</a></td>
<td class="summary">Get the width of a utf8 string for terminal display.</td>
</tr>
</table>
<h2><a href="#Time">Time </a></h2>
<table class="function_list">
<tr>
<td class="name" nowrap><a href="#gettime">gettime ()</a></td>
<td class="summary">Get system time.</td>
</tr>
<tr>
<td class="name" nowrap><a href="#monotime">monotime ()</a></td>
<td class="summary">Get monotonic time.</td>
</tr>
<tr>
<td class="name" nowrap><a href="#sleep">sleep (seconds[, precision=16])</a></td>
<td class="summary">Sleep without a busy loop.</td>
</tr>
</table>
<br/>
<br/>
<h2 class="section-header "><a name="Fields"></a>Fields</h2>
<dl class="function">
<dt>
<a name = "windows"></a>
<strong>windows</strong>
</dt>
<dd>
Flag to identify Windows.
<ul>
<li><span class="parameter">windows</span>
<code>true</code> if on Windows, <code>false</code> otherwise.
</li>
</ul>
</dd>
</dl>
<h2 class="section-header "><a name="Environment"></a>Environment </h2>
<dl class="function">
<dt>
<a name = "getenv"></a>
<strong>getenv (name)</strong>
</dt>
<dd>
Gets the value of an environment variable. </p>
<p><strong>NOTE</strong>: Windows has multiple copies of environment variables. For this reason,
the <a href="../modules/system.html#setenv">setenv</a> function will not work with Lua's <a href="https://www.lua.org/manual/5.4/manual.html#pdf-os.getenv">os.getenv</a> on Windows. If you want
to use <a href="../modules/system.html#setenv">setenv</a> then consider patching <a href="https://www.lua.org/manual/5.4/manual.html#pdf-os.getenv">os.getenv</a> with this implementation of <a href="../modules/system.html#getenv">getenv</a>.
<h3>Parameters:</h3>
<ul>
<li><span class="parameter">name</span>
<span class="types"><a class="type" href="https://www.lua.org/manual/5.4/manual.html#6.4">string</a></span>
name of the environment variable
</li>
</ul>
<h3>Returns:</h3>
<ol>
<span class="types"><a class="type" href="https://www.lua.org/manual/5.4/manual.html#6.4">string</a> or <span class="type">nil</span></span>
value of the environment variable, or nil if the variable is not set
</ol>
</dd>
<dt>
<a name = "getenvs"></a>
<strong>getenvs ()</strong>
</dt>
<dd>
Returns a table with all environment variables.
<h3>Returns:</h3>
<ol>
<span class="types"><a class="type" href="https://www.lua.org/manual/5.4/manual.html#6.6">table</a></span>
table with all environment variables and their values
</ol>
</dd>
<dt>
<a name = "setenv"></a>
<strong>setenv (name[, value])</strong>
</dt>
<dd>
Sets an environment variable. </p>
<p><strong>NOTE</strong>: Windows has multiple copies of environment variables. For this reason, the
<a href="../modules/system.html#setenv">setenv</a> function will not work with Lua's <a href="https://www.lua.org/manual/5.4/manual.html#pdf-os.getenv">os.getenv</a> on Windows. If you want to use
it then consider patching <a href="https://www.lua.org/manual/5.4/manual.html#pdf-os.getenv">os.getenv</a> with the implementation of <a href="../modules/system.html#getenv">system.getenv</a>.
<h3>Parameters:</h3>
<ul>
<li><span class="parameter">name</span>
<span class="types"><a class="type" href="https://www.lua.org/manual/5.4/manual.html#6.4">string</a></span>
name of the environment variable
</li>
<li><span class="parameter">value</span>
<span class="types"><a class="type" href="https://www.lua.org/manual/5.4/manual.html#6.4">string</a></span>
value of the environment variable, if <code>nil</code> the variable will be deleted (on
Windows, setting an empty string, will also delete the variable)
(<em>optional</em>)
</li>
</ul>
<h3>Returns:</h3>
<ol>
<span class="types"><span class="type">boolean</span></span>
success
</ol>
</dd>
</dl>
<h2 class="section-header "><a name="Random"></a>Random </h2>
<dl class="function">
<dt>
<a name = "random"></a>
<strong>random ([length=1])</strong>
</dt>
<dd>
Generate random bytes.
This uses <code>CryptGenRandom()</code> on Windows, and <code>/dev/urandom</code> on other platforms. It will return the
requested number of bytes, or an error, never a partial result.
<h3>Parameters:</h3>
<ul>
<li><span class="parameter">length</span>
<span class="types"><span class="type">int</span></span>
number of bytes to get
(<em>default</em> 1)
</li>
</ul>
<h3>Returns:</h3>
<ol>
<span class="types"><a class="type" href="https://www.lua.org/manual/5.4/manual.html#6.4">string</a></span>
string of random bytes
</ol>
<h3>Or</h3>
<ol>
<li>
<span class="types"><span class="type">nil</span></span>
</li>
<li>
<span class="types"><a class="type" href="https://www.lua.org/manual/5.4/manual.html#6.4">string</a></span>
error message</li>
</ol>
</dd>
</dl>
<h2 class="section-header has-description"><a name="Terminal"></a>Terminal </h2>
<div class="section-description">
Unix: see https://blog.nelhage.com/2009/12/a-brief-introduction-to-termios-termios3-and-stty/</p>
<p> Windows: see https://learn.microsoft.com/en-us/windows/console/console-reference
</div>
<dl class="function">
<dt>
<a name = "CODEPAGE_UTF8"></a>
<strong>CODEPAGE_UTF8</strong>
</dt>
<dd>
UTF8 codepage.
To be used with <a href="../modules/system.html#setconsoleoutputcp">system.setconsoleoutputcp</a> and <a href="../modules/system.html#setconsolecp">system.setconsolecp</a>.
<ul>
<li><span class="parameter">CODEPAGE_UTF8</span>
The Windows CodePage for UTF8.
</li>
</ul>
</dd>
<dt>
<a name = "_readkey"></a>
<strong>_readkey ()</strong>
</dt>
<dd>
Reads a key from the console non-blocking. This function should not be called
directly, but through the <a href="../modules/system.html#readkey">system.readkey</a> or <a href="../modules/system.html#readansi">system.readansi</a> functions. It
will return the next byte from the input stream, or <code>nil</code> if no key was pressed.</p>
<p>On Posix, <a href="https://www.lua.org/manual/5.4/manual.html#pdf-io.stdin">io.stdin</a> must be set to non-blocking mode using <a href="../modules/system.html#setnonblock">setnonblock</a>
and canonical mode must be turned off using <a href="../modules/system.html#tcsetattr">tcsetattr</a>,
before calling this function. Otherwise it will block. No conversions are
done on Posix, so the byte read is returned as-is.</p>
<p>On Windows this reads a wide character and converts it to UTF-8. Multi-byte
sequences will be buffered internally and returned one byte at a time.
<h3>Returns:</h3>
<ol>
<span class="types"><span class="type">integer</span></span>
the byte read from the input stream
</ol>
<h3>Or</h3>
<ol>
<span class="types"><span class="type">nil</span></span>
if no key was pressed
</ol>
<h3>Or</h3>
<ol>
<li>
<span class="types"><span class="type">nil</span></span>
on error</li>
<li>
<span class="types"><a class="type" href="https://www.lua.org/manual/5.4/manual.html#6.4">string</a></span>
error message</li>
<li>
<span class="types"><span class="type">int</span></span>
errnum (on posix)</li>
</ol>
</dd>
<dt>
<a name = "autotermrestore"></a>
<strong>autotermrestore ()</strong>
</dt>
<dd>
Backs up terminal settings and restores them on application exit.
Calls <a href="../modules/system.html#termbackup">termbackup</a> to back up terminal settings and sets up a GC method to
automatically restore them on application exit (also works on Lua 5.1).
<h3>Returns:</h3>
<ol>
<span class="types"><span class="type">boolean</span></span>
true
</ol>
<h3>Or</h3>
<ol>
<li>
<span class="types"><span class="type">nil</span></span>
if the backup was already created</li>
<li>
<span class="types"><a class="type" href="https://www.lua.org/manual/5.4/manual.html#6.4">string</a></span>
error message</li>
</ol>
</dd>
<dt>
<a name = "getconsolecp"></a>
<strong>getconsolecp ()</strong>
</dt>
<dd>
Gets the current console code page (Windows).
<h3>Returns:</h3>
<ol>
<span class="types"><span class="type">int</span></span>
the current code page (always 65001 on Posix systems)
</ol>
</dd>
<dt>
<a name = "getconsoleflags"></a>
<strong>getconsoleflags (file)</strong>
</dt>
<dd>
Gets console flags (Windows).
The <code>CIF_</code> and <code>COF_</code> constants are available on the module table. Where <code>CIF</code> are the
input flags (for use with <a href="https://www.lua.org/manual/5.4/manual.html#pdf-io.stdin">io.stdin</a>) and <code>COF</code> are the output flags (for use with
<a href="https://www.lua.org/manual/5.4/manual.html#pdf-io.stdout">io.stdout</a>/<a href="https://www.lua.org/manual/5.4/manual.html#pdf-io.stderr">io.stderr</a>).</p>
<p><em>Note</em>: See <a href="https://learn.microsoft.com/en-us/windows/console/setconsolemode">setconsolemode documentation</a>
for more information on the flags.
<h3>Parameters:</h3>
<ul>
<li><span class="parameter">file</span>
<span class="types"><span class="type">file</span></span>
file handle to operate on, one of <a href="https://www.lua.org/manual/5.4/manual.html#pdf-io.stdin">io.stdin</a>, <a href="https://www.lua.org/manual/5.4/manual.html#pdf-io.stdout">io.stdout</a>, <a href="https://www.lua.org/manual/5.4/manual.html#pdf-io.stderr">io.stderr</a>
</li>
</ul>
<h3>Returns:</h3>
<ol>
<span class="types"><a class="type" href="../classes/bitflags.html#">bitflags</a></span>
the current console flags.
</ol>
<h3>Or</h3>
<ol>
<li>
<span class="types"><span class="type">nil</span></span>
</li>
<li>
<span class="types"><a class="type" href="https://www.lua.org/manual/5.4/manual.html#6.4">string</a></span>
error message</li>
</ol>
<h3>Usage:</h3>
<ul>
<pre class="example"><span class="keyword">local</span> system = <span class="global">require</span>(<span class="string">'system'</span>)
<span class="keyword">local</span> flags = system.<span class="function-name">getconsoleflags</span>(<span class="global">io</span>.stdout)
<span class="global">print</span>(<span class="string">"Current stdout flags:"</span>, <span class="global">tostring</span>(flags))
<span class="keyword">if</span> flags:<span class="function-name">has_all_of</span>(system.COF_VIRTUAL_TERMINAL_PROCESSING + system.COF_PROCESSED_OUTPUT) <span class="keyword">then</span>
<span class="global">print</span>(<span class="string">"Both flags are set"</span>)
<span class="keyword">else</span>
<span class="global">print</span>(<span class="string">"At least one flag is not set"</span>)
<span class="keyword">end</span></pre>
</ul>
</dd>
<dt>
<a name = "getconsoleoutputcp"></a>
<strong>getconsoleoutputcp ()</strong>
</dt>
<dd>
Gets the current console output code page (Windows).
<h3>Returns:</h3>
<ol>
<span class="types"><span class="type">int</span></span>
the current code page (always 65001 on Posix systems)
</ol>
</dd>
<dt>
<a name = "getnonblock"></a>
<strong>getnonblock (fd)</strong>
</dt>
<dd>
Gets non-blocking mode status for a file (Posix).
<h3>Parameters:</h3>
<ul>
<li><span class="parameter">fd</span>
<span class="types"><span class="type">file</span></span>
file handle to operate on, one of <a href="https://www.lua.org/manual/5.4/manual.html#pdf-io.stdin">io.stdin</a>, <a href="https://www.lua.org/manual/5.4/manual.html#pdf-io.stdout">io.stdout</a>, <a href="https://www.lua.org/manual/5.4/manual.html#pdf-io.stderr">io.stderr</a>
</li>
</ul>
<h3>Returns:</h3>
<ol>
<span class="types"><span class="type">bool</span></span>
<code>true</code> if set to non-blocking, <code>false</code> if not. Always returns <code>false</code> on Windows.
</ol>
<h3>Or</h3>
<ol>
<li>
<span class="types"><span class="type">nil</span></span>
</li>
<li>
<span class="types"><a class="type" href="https://www.lua.org/manual/5.4/manual.html#6.4">string</a></span>
error message</li>
<li>
<span class="types"><span class="type">int</span></span>
errnum</li>
</ol>
</dd>
<dt>
<a name = "isatty"></a>
<strong>isatty (file)</strong>
</dt>
<dd>
Checks if a file-handle is a TTY.
<h3>Parameters:</h3>
<ul>
<li><span class="parameter">file</span>
<span class="types"><span class="type">file</span></span>
the file-handle to check, one of <a href="https://www.lua.org/manual/5.4/manual.html#pdf-io.stdin">io.stdin</a>, <a href="https://www.lua.org/manual/5.4/manual.html#pdf-io.stdout">io.stdout</a>, <a href="https://www.lua.org/manual/5.4/manual.html#pdf-io.stderr">io.stderr</a>.
</li>
</ul>
<h3>Returns:</h3>
<ol>
<span class="types"><span class="type">boolean</span></span>
true if the file is a tty
</ol>
<h3>Usage:</h3>
<ul>
<pre class="example"><span class="keyword">local</span> system = <span class="global">require</span>(<span class="string">'system'</span>)
<span class="keyword">if</span> system.<span class="function-name">isatty</span>(<span class="global">io</span>.stdin) <span class="keyword">then</span>
<span class="comment">-- enable ANSI coloring etc on Windows, does nothing in Posix.
</span> <span class="keyword">local</span> flags = system.<span class="function-name">getconsoleflags</span>(<span class="global">io</span>.stdout)
system.<span class="function-name">setconsoleflags</span>(<span class="global">io</span>.stdout, flags + sys.COF_VIRTUAL_TERMINAL_PROCESSING)
<span class="keyword">end</span></pre>
</ul>
</dd>
<dt>
<a name = "listconsoleflags"></a>
<strong>listconsoleflags (fh)</strong>
</dt>
<dd>
Debug function for console flags (Windows).
Pretty prints the current flags set for the handle.
<h3>Parameters:</h3>
<ul>
<li><span class="parameter">fh</span>
file handle (<a href="https://www.lua.org/manual/5.4/manual.html#pdf-io.stdin">io.stdin</a>, <a href="https://www.lua.org/manual/5.4/manual.html#pdf-io.stdout">io.stdout</a>, <a href="https://www.lua.org/manual/5.4/manual.html#pdf-io.stderr">io.stderr</a>)
</li>
</ul>
<h3>Usage:</h3>
<ul>
<pre class="example"><span class="comment">-- Print the flags for stdin/out/err
</span>system.<span class="function-name">listconsoleflags</span>(<span class="global">io</span>.stdin)
system.<span class="function-name">listconsoleflags</span>(<span class="global">io</span>.stdout)
system.<span class="function-name">listconsoleflags</span>(<span class="global">io</span>.stderr)</pre>
</ul>
</dd>
<dt>
<a name = "listtermflags"></a>
<strong>listtermflags (fh)</strong>
</dt>
<dd>
Debug function for terminal flags (Posix).
Pretty prints the current flags set for the handle.
<h3>Parameters:</h3>
<ul>
<li><span class="parameter">fh</span>
file handle (<a href="https://www.lua.org/manual/5.4/manual.html#pdf-io.stdin">io.stdin</a>, <a href="https://www.lua.org/manual/5.4/manual.html#pdf-io.stdout">io.stdout</a>, <a href="https://www.lua.org/manual/5.4/manual.html#pdf-io.stderr">io.stderr</a>)
</li>
</ul>
<h3>Usage:</h3>
<ul>
<pre class="example"><span class="comment">-- Print the flags for stdin/out/err
</span>system.<span class="function-name">listconsoleflags</span>(<span class="global">io</span>.stdin)
system.<span class="function-name">listconsoleflags</span>(<span class="global">io</span>.stdout)
system.<span class="function-name">listconsoleflags</span>(<span class="global">io</span>.stderr)</pre>
</ul>
</dd>
<dt>
<a name = "readansi"></a>
<strong>readansi (timeout)</strong>
</dt>
<dd>
Reads a single key, if it is the start of ansi escape sequence then it reads
the full sequence. The key can be a multi-byte string in case of multibyte UTF-8 character.
This function uses <a href="../modules/system.html#readkey">system.readkey</a>, and hence <a href="../modules/system.html#sleep">system.sleep</a> to wait until either a key is
available or the timeout is reached.
It returns immediately if a key is available or if <code>timeout</code> is less than or equal to <code>0</code>.
In case of an ANSI sequence, it will return the full sequence as a string.
<h3>Parameters:</h3>
<ul>
<li><span class="parameter">timeout</span>
<span class="types"><span class="type">number</span></span>
the timeout in seconds.
</li>
</ul>
<h3>Returns:</h3>
<ol>
<li>
<span class="types"><a class="type" href="https://www.lua.org/manual/5.4/manual.html#6.4">string</a></span>
the character that was received (can be multi-byte), or a complete ANSI sequence</li>
<li>
<span class="types"><a class="type" href="https://www.lua.org/manual/5.4/manual.html#6.4">string</a></span>
the type of input: <code>"char"</code> for a single key, <code>"ansi"</code> for an ANSI sequence</li>
</ol>
<h3>Or</h3>
<ol>
<li>
<span class="types"><span class="type">nil</span></span>
in case of an error</li>
<li>
<span class="types"><a class="type" href="https://www.lua.org/manual/5.4/manual.html#6.4">string</a></span>
error message; <code>"timeout"</code> if the timeout was reached.</li>
<li>
<span class="types"><a class="type" href="https://www.lua.org/manual/5.4/manual.html#6.4">string</a></span>
partial result in case of an error while reading a sequence, the sequence so far.</li>
</ol>
</dd>
<dt>
<a name = "readkey"></a>
<strong>readkey (timeout)</strong>
</dt>
<dd>
Reads a single byte from the console, with a timeout.
This function uses <a href="../modules/system.html#sleep">system.sleep</a> to wait until either a byte is available or the timeout is reached.
The sleep period is exponentially backing off, starting at 0.0125 seconds, with a maximum of 0.2 seconds.
It returns immediately if a byte is available or if <code>timeout</code> is less than or equal to <code>0</code>.</p>
<p> Using <a href="../modules/system.html#readansi">system.readansi</a> is preferred over this function. Since this function can leave stray/invalid
byte-sequences in the input buffer, while <a href="../modules/system.html#readansi">system.readansi</a> reads full ANSI and UTF8 sequences.
<h3>Parameters:</h3>
<ul>
<li><span class="parameter">timeout</span>
<span class="types"><span class="type">number</span></span>
the timeout in seconds.
</li>
</ul>
<h3>Returns:</h3>
<ol>
<span class="types"><span class="type">byte</span></span>
the byte value that was read.
</ol>
<h3>Or</h3>
<ol>
<li>
<span class="types"><span class="type">nil</span></span>
if no key was read</li>
<li>
<span class="types"><a class="type" href="https://www.lua.org/manual/5.4/manual.html#6.4">string</a></span>
error message; <code>"timeout"</code> if the timeout was reached.</li>
</ol>
</dd>
<dt>
<a name = "setconsolecp"></a>
<strong>setconsolecp (cp)</strong>
</dt>
<dd>
Sets the current console code page (Windows).
<h3>Parameters:</h3>
<ul>
<li><span class="parameter">cp</span>
<span class="types"><span class="type">int</span></span>
the code page to set, use <a href="../modules/system.html#CODEPAGE_UTF8">system.CODEPAGE_UTF8</a> (65001) for UTF-8
</li>
</ul>
<h3>Returns:</h3>
<ol>
<span class="types"><span class="type">bool</span></span>
<code>true</code> on success (always <code>true</code> on Posix systems)
</ol>
</dd>
<dt>
<a name = "setconsoleflags"></a>
<strong>setconsoleflags (file, bitflags)</strong>
</dt>
<dd>
Sets the console flags (Windows).
The <code>CIF_</code> and <code>COF_</code> constants are available on the module table. Where <code>CIF</code> are the
input flags (for use with <a href="https://www.lua.org/manual/5.4/manual.html#pdf-io.stdin">io.stdin</a>) and <code>COF</code> are the output flags (for use with
<a href="https://www.lua.org/manual/5.4/manual.html#pdf-io.stdout">io.stdout</a>/<a href="https://www.lua.org/manual/5.4/manual.html#pdf-io.stderr">io.stderr</a>).</p>
<p>To see flag status and constant names check <a href="../modules/system.html#listconsoleflags">listconsoleflags</a>.</p>
<p>Note: not all combinations of flags are allowed, as some are mutually exclusive or mutually required.
See <a href="https://learn.microsoft.com/en-us/windows/console/setconsolemode">setconsolemode documentation</a>
<h3>Parameters:</h3>
<ul>
<li><span class="parameter">file</span>
<span class="types"><span class="type">file</span></span>
file handle to operate on, one of <a href="https://www.lua.org/manual/5.4/manual.html#pdf-io.stdin">io.stdin</a>, <a href="https://www.lua.org/manual/5.4/manual.html#pdf-io.stdout">io.stdout</a>, <a href="https://www.lua.org/manual/5.4/manual.html#pdf-io.stderr">io.stderr</a>
</li>
<li><span class="parameter">bitflags</span>
<span class="types"><a class="type" href="../classes/bitflags.html#">bitflags</a></span>
the flags to set/unset
</li>
</ul>
<h3>Returns:</h3>
<ol>
<span class="types"><span class="type">boolean</span></span>
<code>true</code> on success
</ol>
<h3>Or</h3>
<ol>
<li>
<span class="types"><span class="type">nil</span></span>
</li>
<li>
<span class="types"><a class="type" href="https://www.lua.org/manual/5.4/manual.html#6.4">string</a></span>
error message</li>
</ol>
<h3>Usage:</h3>
<ul>
<pre class="example"><span class="keyword">local</span> system = <span class="global">require</span>(<span class="string">'system'</span>)
system.<span class="function-name">listconsoleflags</span>(<span class="global">io</span>.stdout) <span class="comment">-- List all the available flags and their current status
</span>
<span class="keyword">local</span> flags = system.<span class="function-name">getconsoleflags</span>(<span class="global">io</span>.stdout)
<span class="global">assert</span>(system.<span class="function-name">setconsoleflags</span>(<span class="global">io</span>.stdout,
flags + system.COF_VIRTUAL_TERMINAL_PROCESSING)
system.<span class="function-name">listconsoleflags</span>(<span class="global">io</span>.stdout) <span class="comment">-- List again to check the differences</span></pre>
</ul>
</dd>
<dt>
<a name = "setconsoleoutputcp"></a>
<strong>setconsoleoutputcp (cp)</strong>
</dt>
<dd>
Sets the current console output code page (Windows).
<h3>Parameters:</h3>
<ul>
<li><span class="parameter">cp</span>
<span class="types"><span class="type">int</span></span>
the code page to set, use <a href="../modules/system.html#CODEPAGE_UTF8">system.CODEPAGE_UTF8</a> (65001) for UTF-8
</li>
</ul>
<h3>Returns:</h3>
<ol>
<span class="types"><span class="type">bool</span></span>
<code>true</code> on success (always <code>true</code> on Posix systems)
</ol>
</dd>
<dt>
<a name = "setnonblock"></a>
<strong>setnonblock (fd, make_non_block)</strong>
</dt>
<dd>
Enables or disables non-blocking mode for a file (Posix).
<h3>Parameters:</h3>
<ul>
<li><span class="parameter">fd</span>
<span class="types"><span class="type">file</span></span>
file handle to operate on, one of <a href="https://www.lua.org/manual/5.4/manual.html#pdf-io.stdin">io.stdin</a>, <a href="https://www.lua.org/manual/5.4/manual.html#pdf-io.stdout">io.stdout</a>, <a href="https://www.lua.org/manual/5.4/manual.html#pdf-io.stderr">io.stderr</a>
</li>
<li><span class="parameter">make_non_block</span>
<span class="types"><span class="type">boolean</span></span>
a truthy value will enable non-blocking mode, a falsy value will disable it.
</li>
</ul>
<h3>Returns:</h3>
<ol>
<span class="types"><span class="type">bool</span></span>
<code>true</code>, if successful
</ol>
<h3>Or</h3>
<ol>
<li>
<span class="types"><span class="type">nil</span></span>
</li>
<li>
<span class="types"><a class="type" href="https://www.lua.org/manual/5.4/manual.html#6.4">string</a></span>
error message</li>
<li>
<span class="types"><span class="type">int</span></span>
errnum</li>
</ol>
<h3>See also:</h3>
<ul>
<a href="../modules/system.html#getnonblock">getnonblock</a>
</ul>
<h3>Usage:</h3>
<ul>
<pre class="example"><span class="keyword">local</span> sys = <span class="global">require</span>(<span class="string">'system'</span>)
<span class="comment">-- set io.stdin to non-blocking mode
</span><span class="keyword">local</span> old_setting = sys.<span class="function-name">getnonblock</span>(<span class="global">io</span>.stdin)
sys.<span class="function-name">setnonblock</span>(<span class="global">io</span>.stdin, <span class="keyword">true</span>)
<span class="comment">-- do stuff
</span>
<span class="comment">-- restore old setting
</span>sys.<span class="function-name">setnonblock</span>(<span class="global">io</span>.stdin, old_setting)</pre>
</ul>
</dd>
<dt>
<a name = "tcgetattr"></a>
<strong>tcgetattr (fd)</strong>
</dt>
<dd>
<p>Get termios state (Posix).
The terminal attributes is a table with the following fields:</p>
<ul>
<li><code>iflag</code> input flags</li>
<li><code>oflag</code> output flags</li>
<li><code>lflag</code> local flags</li>
<li><code>cflag</code> control flags</li>
<li><code>ispeed</code> input speed</li>
<li><code>ospeed</code> output speed</li>
<li><code>cc</code> control characters</li>
</ul>
<h3>Parameters:</h3>
<ul>
<li><span class="parameter">fd</span>
<span class="types"><span class="type">file</span></span>
file handle to operate on, one of <a href="https://www.lua.org/manual/5.4/manual.html#pdf-io.stdin">io.stdin</a>, <a href="https://www.lua.org/manual/5.4/manual.html#pdf-io.stdout">io.stdout</a>, <a href="https://www.lua.org/manual/5.4/manual.html#pdf-io.stderr">io.stderr</a>
</li>
</ul>
<h3>Returns:</h3>
<ol>
error message if failed
</ol>
<h3>Or</h3>
<ol>
<span class="types"><span class="type">termios</span></span>
terminal attributes, if successful. On Windows the bitflags are all 0, and the <code>cc</code> table is empty.
</ol>
<h3>Or</h3>
<ol>
<li>
<span class="types"><span class="type">nil</span></span>
</li>
<li>
<span class="types"><a class="type" href="https://www.lua.org/manual/5.4/manual.html#6.4">string</a></span>
error message</li>
<li>
<span class="types"><span class="type">int</span></span>
errnum</li>
</ol>
<h3>Usage:</h3>
<ul>
<pre class="example"><span class="keyword">local</span> system = <span class="global">require</span>(<span class="string">'system'</span>)
<span class="keyword">local</span> status = <span class="global">assert</span>(<span class="function-name">tcgetattr</span>(<span class="global">io</span>.stdin))
<span class="keyword">if</span> status.iflag:<span class="function-name">has_all_of</span>(system.I_IGNBRK) <span class="keyword">then</span>
<span class="global">print</span>(<span class="string">"Ignoring break condition"</span>)
<span class="keyword">end</span></pre>
</ul>
</dd>
<dt>
<a name = "tcsetattr"></a>
<strong>tcsetattr (fd, actions, termios)</strong>
</dt>
<dd>
Set termios state (Posix).
This function will set the flags as given.</p>
<p>The <code>I_</code>, <code>O_</code>, and <code>L_</code> constants are available on the module table. They are the respective
flags for the <code>iflags</code>, <code>oflags</code>, and <code>lflags</code> bitmasks.</p>
<p>To see flag status and constant names check <a href="../modules/system.html#listtermflags">listtermflags</a>. For their meaning check
<a href="https://www.man7.org/linux/man-pages/man3/termios.3.html">the manpage</a>.</p>
<p><em>Note</em>: only <code>iflag</code>, <code>oflag</code>, and <code>lflag</code> are supported at the moment. The other fields are ignored.
<h3>Parameters:</h3>
<ul>
<li><span class="parameter">fd</span>
<span class="types"><span class="type">file</span></span>
file handle to operate on, one of <a href="https://www.lua.org/manual/5.4/manual.html#pdf-io.stdin">io.stdin</a>, <a href="https://www.lua.org/manual/5.4/manual.html#pdf-io.stdout">io.stdout</a>, <a href="https://www.lua.org/manual/5.4/manual.html#pdf-io.stderr">io.stderr</a>
</li>
<li><span class="parameter">actions</span>
<span class="types"><span class="type">integer</span></span>
one of <code>TCSANOW</code>, <code>TCSADRAIN</code>, <code>TCSAFLUSH</code>
</li>
<li><span class="parameter">termios</span> a table with bitflag fields:
<ul>
<li><span class="parameter">iflag</span>
<span class="types"><a class="type" href="../classes/bitflags.html#">bitflags</a></span>
if given will set the input flags
(<em>optional</em>)
</li>
<li><span class="parameter">oflag</span>
<span class="types"><a class="type" href="../classes/bitflags.html#">bitflags</a></span>
if given will set the output flags
(<em>optional</em>)
</li>
<li><span class="parameter">lflag</span>
<span class="types"><a class="type" href="../classes/bitflags.html#">bitflags</a></span>
if given will set the local flags
(<em>optional</em>)
</li>
</li></ul>
</ul>
<h3>Returns:</h3>
<ol>
<span class="types"><span class="type">bool</span></span>
<code>true</code>, if successful. Always returns <code>true</code> on Windows.
</ol>
<h3>Or</h3>
<ol>
<li>
nil</li>
<li>
<span class="types"><a class="type" href="https://www.lua.org/manual/5.4/manual.html#6.4">string</a></span>
error message</li>
<li>
<span class="types"><span class="type">int</span></span>
errnum</li>
</ol>
<h3>Usage:</h3>
<ul>
<pre class="example"><span class="keyword">local</span> system = <span class="global">require</span>(<span class="string">'system'</span>)
<span class="keyword">local</span> status = <span class="global">assert</span>(<span class="function-name">tcgetattr</span>(<span class="global">io</span>.stdin))
<span class="keyword">if</span> <span class="keyword">not</span> status.lflag:<span class="function-name">has_all_of</span>(system.L_ECHO) <span class="keyword">then</span>
<span class="comment">-- if echo is off, turn echoing newlines on
</span> <span class="function-name">tcsetattr</span>(<span class="global">io</span>.stdin, system.TCSANOW, { lflag = status.lflag + system.L_ECHONL }))
<span class="keyword">end</span></pre>
</ul>
</dd>
<dt>
<a name = "termbackup"></a>
<strong>termbackup ()</strong>
</dt>
<dd>
Returns a backup of terminal settings for stdin/out/err.
Handles terminal/console flags, Windows codepage, and non-block flags on the streams.
Backs up terminal/console flags only if a stream is a tty.
<h3>Returns:</h3>
<ol>
table with backup of terminal settings
</ol>
</dd>
<dt>
<a name = "termrestore"></a>
<strong>termrestore (backup)</strong>
</dt>
<dd>
Restores terminal settings from a backup
<h3>Parameters:</h3>
<ul>
<li><span class="parameter">backup</span>
<span class="types"><a class="type" href="https://www.lua.org/manual/5.4/manual.html#6.6">table</a></span>
the backup of terminal settings, see <a href="../modules/system.html#termbackup">termbackup</a>.
</li>
</ul>
<h3>Returns:</h3>
<ol>
<span class="types"><span class="type">boolean</span></span>
true
</ol>
</dd>
<dt>
<a name = "termsize"></a>
<strong>termsize ()</strong>
</dt>
<dd>
Get the size of the terminal in rows and columns.
<h3>Returns:</h3>
<ol>
<li>
<span class="types"><span class="type">int</span></span>
the number of rows</li>
<li>
<span class="types"><span class="type">int</span></span>
the number of columns</li>
</ol>
<h3>Or</h3>
<ol>
<li>
<span class="types"><span class="type">nil</span></span>
</li>
<li>
<span class="types"><a class="type" href="https://www.lua.org/manual/5.4/manual.html#6.4">string</a></span>
error message</li>
</ol>
</dd>
<dt>
<a name = "termwrap"></a>
<strong>termwrap (f)</strong>
</dt>
<dd>
Wraps a function to automatically restore terminal settings upon returning.
Calls <a href="../modules/system.html#termbackup">termbackup</a> before calling the function and <a href="../modules/system.html#termrestore">termrestore</a> after.
<h3>Parameters:</h3>
<ul>
<li><span class="parameter">f</span>
<span class="types"><span class="type">function</span></span>
function to wrap
</li>
</ul>
<h3>Returns:</h3>
<ol>
<span class="types"><span class="type">function</span></span>
wrapped function
</ol>
</dd>
<dt>
<a name = "utf8cwidth"></a>
<strong>utf8cwidth (utf8_char)</strong>
</dt>
<dd>
Get the width of a utf8 character for terminal display.
<h3>Parameters:</h3>
<ul>
<li><span class="parameter">utf8_char</span>
<span class="types"><a class="type" href="https://www.lua.org/manual/5.4/manual.html#6.4">string</a></span>
the utf8 character to check, only the width of the first character will be returned
</li>
</ul>
<h3>Returns:</h3>
<ol>
<span class="types"><span class="type">int</span></span>
the display width in columns of the first character in the string (0 for an empty string)
</ol>
<h3>Or</h3>
<ol>
<li>
<span class="types"><span class="type">nil</span></span>
</li>
<li>
<span class="types"><a class="type" href="https://www.lua.org/manual/5.4/manual.html#6.4">string</a></span>
error message</li>
</ol>
</dd>
<dt>
<a name = "utf8swidth"></a>
<strong>utf8swidth (utf8_string)</strong>
</dt>
<dd>
Get the width of a utf8 string for terminal display.
<h3>Parameters:</h3>
<ul>
<li><span class="parameter">utf8_string</span>
<span class="types"><a class="type" href="https://www.lua.org/manual/5.4/manual.html#6.4">string</a></span>
the utf8 string to check
</li>
</ul>
<h3>Returns:</h3>
<ol>
<span class="types"><span class="type">int</span></span>
the display width of the string in columns (0 for an empty string)
</ol>
<h3>Or</h3>
<ol>
<li>
<span class="types"><span class="type">nil</span></span>
</li>
<li>
<span class="types"><a class="type" href="https://www.lua.org/manual/5.4/manual.html#6.4">string</a></span>
error message</li>
</ol>
</dd>
</dl>
<h2 class="section-header "><a name="Time"></a>Time </h2>
<dl class="function">
<dt>
<a name = "gettime"></a>
<strong>gettime ()</strong>
</dt>
<dd>
Get system time.
The time is returned as the seconds since the epoch (1 January 1970 00:00:00).
<h3>Returns:</h3>
<ol>
<span class="types"><span class="type">number</span></span>
seconds (fractional)
</ol>
</dd>
<dt>
<a name = "monotime"></a>
<strong>monotime ()</strong>
</dt>
<dd>
Get monotonic time.
The time is returned as the seconds since system start.
<h3>Returns:</h3>
<ol>
<span class="types"><span class="type">number</span></span>
seconds (fractional)
</ol>
</dd>
<dt>
<a name = "sleep"></a>
<strong>sleep (seconds[, precision=16])</strong>
</dt>
<dd>
Sleep without a busy loop.
This function will sleep, without doing a busy-loop and wasting CPU cycles.
<h3>Parameters:</h3>
<ul>
<li><span class="parameter">seconds</span>
<span class="types"><span class="type">number</span></span>
seconds to sleep (fractional).
</li>
<li><span class="parameter">precision</span>
<span class="types"><span class="type">integer</span></span>
minimum stepsize in milliseconds (Windows only, ignored elsewhere)
(<em>default</em> 16)
</li>
</ul>
<h3>Returns:</h3>
<ol>
<code>true</code> on success, or <code>nil+err</code> on failure
</ol>
</dd>
</dl>
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