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<table class="head">
<tr>
<td class="head-ltitle">PTY(4)</td>
<td class="head-vol">Device Drivers Manual</td>
<td class="head-rtitle">PTY(4)</td>
</tr>
</table>
<div class="manual-text">
<section class="Sh">
<h1 class="Sh" id="NAME"><a class="permalink" href="#NAME">NAME</a></h1>
<p class="Pp"><code class="Nm">pty</code> — <span class="Nd">old-style
compatibility pseudo-terminal driver</span></p>
</section>
<section class="Sh">
<h1 class="Sh" id="SYNOPSIS"><a class="permalink" href="#SYNOPSIS">SYNOPSIS</a></h1>
<p class="Pp"><code class="Cd">device pty</code></p>
</section>
<section class="Sh">
<h1 class="Sh" id="DESCRIPTION"><a class="permalink" href="#DESCRIPTION">DESCRIPTION</a></h1>
<p class="Pp">The <code class="Nm">pty</code> driver provides support for the
traditional BSD naming scheme that was used for accessing pseudo-terminals
before it was replaced by <a class="Xr">pts(4)</a>. This traditional naming
is still used in Linux. When the device <span class="Pa">/dev/ptyXX</span>
is being opened, a new terminal shall be created with the
<a class="Xr">pts(4)</a> driver. A device node for this terminal shall be
created, which has the name <span class="Pa">/dev/ttyXX</span>.</p>
<p class="Pp">The <code class="Nm">pty</code> driver also provides a cloning
System V <span class="Pa">/dev/ptmx</span> device.</p>
<p class="Pp">New code should not try to allocate pseudo-terminals using this
interface. It is only provided for compatibility with older C libraries that
tried to open such devices when <a class="Xr">posix_openpt(2)</a> was being
called, and for running Linux binaries.</p>
</section>
<section class="Sh">
<h1 class="Sh" id="FILES"><a class="permalink" href="#FILES">FILES</a></h1>
<p class="Pp">The BSD-style compatibility pseudo-terminal driver uses the
following device names:</p>
<dl class="Bl-tag">
<dt><span class="Pa">/dev/pty[l-sL-S][0-9a-v]</span></dt>
<dd>Pseudo-terminal master devices.</dd>
<dt><span class="Pa">/dev/tty[l-sL-S][0-9a-v]</span></dt>
<dd>Pseudo-terminal slave devices.</dd>
<dt><span class="Pa">/dev/ptmx</span></dt>
<dd>Control device, returns a file descriptor to a new master pseudo-terminal
when opened.</dd>
</dl>
</section>
<section class="Sh">
<h1 class="Sh" id="DIAGNOSTICS"><a class="permalink" href="#DIAGNOSTICS">DIAGNOSTICS</a></h1>
<p class="Pp">None.</p>
</section>
<section class="Sh">
<h1 class="Sh" id="SEE_ALSO"><a class="permalink" href="#SEE_ALSO">SEE
ALSO</a></h1>
<p class="Pp"><a class="Xr">posix_openpt(2)</a>, <a class="Xr">pts(4)</a>,
<a class="Xr">tty(4)</a></p>
</section>
<section class="Sh">
<h1 class="Sh" id="HISTORY"><a class="permalink" href="#HISTORY">HISTORY</a></h1>
<p class="Pp">A pseudo-terminal driver appeared in
<span class="Ux">4.2BSD</span>.</p>
</section>
<section class="Sh">
<h1 class="Sh" id="BUGS"><a class="permalink" href="#BUGS">BUGS</a></h1>
<p class="Pp">Unlike previous implementations, the master and slave device nodes
are destroyed when the PTY becomes unused. A call to
<a class="Xr">stat(2)</a> on a nonexistent master device will already cause
a new master device node to be created. The master device can only be
destroyed by opening and closing it.</p>
<p class="Pp">The <code class="Nm">pty</code> driver cannot be unloaded, because
it cannot determine if it is being used.</p>
</section>
</div>
<table class="foot">
<tr>
<td class="foot-date">October 28, 2019</td>
<td class="foot-os">FreeBSD 15.0</td>
</tr>
</table>
|
