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<h3 class="section">27.3 Controlling Terminal of a Process</h3>

<p>One of the attributes of a process is its controlling terminal.  Child
processes created with <code>fork</code> inherit the controlling terminal from
their parent process.  In this way, all the processes in a session
inherit the controlling terminal from the session leader.  A session
leader that has control of a terminal is called the <dfn>controlling
process</dfn> of that terminal.

   <p><a name="index-controlling-process-3208"></a>You generally do not need to worry about the exact mechanism used to
allocate a controlling terminal to a session, since it is done for you
by the system when you log in. 
<!-- ??? How does GNU system let a process get a ctl terminal. -->

   <p>An individual process disconnects from its controlling terminal when it
calls <code>setsid</code> to become the leader of a new session. 
See <a href="Process-Group-Functions.html#Process-Group-Functions">Process Group Functions</a>.

<!-- !!! explain how it gets a new one (by opening any terminal) -->
<!-- ??? How you get a controlling terminal is system-dependent. -->
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