Edit File: termios.html
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Unix Specific Services</a> »</li> </ul> </div> <div class="document"> <div class="documentwrapper"> <div class="bodywrapper"> <div class="body"> <div class="section" id="module-termios"> <h1>35.7. <tt class="xref docutils literal"><span class="pre">termios</span></tt> — POSIX style tty control<a class="headerlink" href="#module-termios" title="Permalink to this headline">¶</a></h1> <p><em>Platforms: </em>Unix</p> <p id="index-661">This module provides an interface to the POSIX calls for tty I/O control. For a complete description of these calls, see the POSIX or Unix manual pages. It is only available for those Unix versions that support POSIX <em>termios</em> style tty I/O control (and then only if configured at installation time).</p> <p>All functions in this module take a file descriptor <em>fd</em> as their first argument. This can be an integer file descriptor, such as returned by <tt class="docutils literal"><span class="pre">sys.stdin.fileno()</span></tt>, or a file object, such as <tt class="docutils literal"><span class="pre">sys.stdin</span></tt> itself.</p> <p>This module also defines all the constants needed to work with the functions provided here; these have the same name as their counterparts in C. Please refer to your system documentation for more information on using these terminal control interfaces.</p> <p>The module defines the following functions:</p> <dl class="function"> <dt id="termios.tcgetattr"> <tt class="descclassname">termios.</tt><tt class="descname">tcgetattr</tt><big>(</big><em>fd</em><big>)</big><a class="headerlink" href="#termios.tcgetattr" title="Permalink to this definition">¶</a></dt> <dd>Return a list containing the tty attributes for file descriptor <em>fd</em>, as follows: <tt class="docutils literal"><span class="pre">[iflag,</span> <span class="pre">oflag,</span> <span class="pre">cflag,</span> <span class="pre">lflag,</span> <span class="pre">ispeed,</span> <span class="pre">ospeed,</span> <span class="pre">cc]</span></tt> where <em>cc</em> is a list of the tty special characters (each a string of length 1, except the items with indices <tt class="xref docutils literal"><span class="pre">VMIN</span></tt> and <tt class="xref docutils literal"><span class="pre">VTIME</span></tt>, which are integers when these fields are defined). The interpretation of the flags and the speeds as well as the indexing in the <em>cc</em> array must be done using the symbolic constants defined in the <tt class="xref docutils literal"><span class="pre">termios</span></tt> module.</dd></dl> <dl class="function"> <dt id="termios.tcsetattr"> <tt class="descclassname">termios.</tt><tt class="descname">tcsetattr</tt><big>(</big><em>fd</em>, <em>when</em>, <em>attributes</em><big>)</big><a class="headerlink" href="#termios.tcsetattr" title="Permalink to this definition">¶</a></dt> <dd>Set the tty attributes for file descriptor <em>fd</em> from the <em>attributes</em>, which is a list like the one returned by <a title="termios.tcgetattr" class="reference internal" href="#termios.tcgetattr"><tt class="xref docutils literal"><span class="pre">tcgetattr()</span></tt></a>. The <em>when</em> argument determines when the attributes are changed: <tt class="xref docutils literal"><span class="pre">TCSANOW</span></tt> to change immediately, <tt class="xref docutils literal"><span class="pre">TCSADRAIN</span></tt> to change after transmitting all queued output, or <tt class="xref docutils literal"><span class="pre">TCSAFLUSH</span></tt> to change after transmitting all queued output and discarding all queued input.</dd></dl> <dl class="function"> <dt id="termios.tcsendbreak"> <tt class="descclassname">termios.</tt><tt class="descname">tcsendbreak</tt><big>(</big><em>fd</em>, <em>duration</em><big>)</big><a class="headerlink" href="#termios.tcsendbreak" title="Permalink to this definition">¶</a></dt> <dd>Send a break on file descriptor <em>fd</em>. A zero <em>duration</em> sends a break for 0.25 –0.5 seconds; a nonzero <em>duration</em> has a system dependent meaning.</dd></dl> <dl class="function"> <dt id="termios.tcdrain"> <tt class="descclassname">termios.</tt><tt class="descname">tcdrain</tt><big>(</big><em>fd</em><big>)</big><a class="headerlink" href="#termios.tcdrain" title="Permalink to this definition">¶</a></dt> <dd>Wait until all output written to file descriptor <em>fd</em> has been transmitted.</dd></dl> <dl class="function"> <dt id="termios.tcflush"> <tt class="descclassname">termios.</tt><tt class="descname">tcflush</tt><big>(</big><em>fd</em>, <em>queue</em><big>)</big><a class="headerlink" href="#termios.tcflush" title="Permalink to this definition">¶</a></dt> <dd>Discard queued data on file descriptor <em>fd</em>. The <em>queue</em> selector specifies which queue: <tt class="xref docutils literal"><span class="pre">TCIFLUSH</span></tt> for the input queue, <tt class="xref docutils literal"><span class="pre">TCOFLUSH</span></tt> for the output queue, or <tt class="xref docutils literal"><span class="pre">TCIOFLUSH</span></tt> for both queues.</dd></dl> <dl class="function"> <dt id="termios.tcflow"> <tt class="descclassname">termios.</tt><tt class="descname">tcflow</tt><big>(</big><em>fd</em>, <em>action</em><big>)</big><a class="headerlink" href="#termios.tcflow" title="Permalink to this definition">¶</a></dt> <dd>Suspend or resume input or output on file descriptor <em>fd</em>. The <em>action</em> argument can be <tt class="xref docutils literal"><span class="pre">TCOOFF</span></tt> to suspend output, <tt class="xref docutils literal"><span class="pre">TCOON</span></tt> to restart output, <tt class="xref docutils literal"><span class="pre">TCIOFF</span></tt> to suspend input, or <tt class="xref docutils literal"><span class="pre">TCION</span></tt> to restart input.</dd></dl> <div class="admonition-see-also admonition seealso"> <p class="first admonition-title">See also</p> <dl class="last docutils"> <dt>Module <a title="(Unix) Utility functions that perform common terminal control operations." class="reference external" href="tty.html#module-tty"><tt class="xref docutils literal"><span class="pre">tty</span></tt></a></dt> <dd>Convenience functions for common terminal control operations.</dd> </dl> </div> <div class="section" id="example"> <h2>35.7.1. Example<a class="headerlink" href="#example" title="Permalink to this headline">¶</a></h2> <p id="termios-example">Here’s a function that prompts for a password with echoing turned off. Note the technique using a separate <a title="termios.tcgetattr" class="reference internal" href="#termios.tcgetattr"><tt class="xref docutils literal"><span class="pre">tcgetattr()</span></tt></a> call and a <a class="reference external" href="../reference/compound_stmts.html#try"><tt class="xref docutils literal"><span class="pre">try</span></tt></a> ... <a class="reference external" href="../reference/compound_stmts.html#finally"><tt class="xref docutils literal"><span class="pre">finally</span></tt></a> statement to ensure that the old tty attributes are restored exactly no matter what happens:</p> <div class="highlight-python"><div class="highlight"><pre><span class="k">def</span> <span class="nf">getpass</span><span class="p">(</span><span class="n">prompt</span><span class="o">=</span><span class="s">"Password: "</span><span class="p">):</span> <span class="kn">import</span> <span class="nn">termios</span><span class="o">,</span> <span class="nn">sys</span> <span class="n">fd</span> <span class="o">=</span> <span class="n">sys</span><span class="o">.</span><span class="n">stdin</span><span class="o">.</span><span class="n">fileno</span><span class="p">()</span> <span class="n">old</span> <span class="o">=</span> <span class="n">termios</span><span class="o">.</span><span class="n">tcgetattr</span><span class="p">(</span><span class="n">fd</span><span class="p">)</span> <span class="n">new</span> <span class="o">=</span> <span class="n">termios</span><span class="o">.</span><span class="n">tcgetattr</span><span class="p">(</span><span class="n">fd</span><span class="p">)</span> <span class="n">new</span><span class="p">[</span><span class="mi">3</span><span class="p">]</span> <span class="o">=</span> <span class="n">new</span><span class="p">[</span><span class="mi">3</span><span class="p">]</span> <span class="o">&</span> <span class="o">~</span><span class="n">termios</span><span class="o">.</span><span class="n">ECHO</span> <span class="c"># lflags</span> <span class="k">try</span><span class="p">:</span> <span class="n">termios</span><span class="o">.</span><span class="n">tcsetattr</span><span class="p">(</span><span class="n">fd</span><span class="p">,</span> <span class="n">termios</span><span class="o">.</span><span class="n">TCSADRAIN</span><span class="p">,</span> <span class="n">new</span><span class="p">)</span> <span class="n">passwd</span> <span class="o">=</span> <span class="nb">raw_input</span><span class="p">(</span><span class="n">prompt</span><span class="p">)</span> <span class="k">finally</span><span class="p">:</span> <span class="n">termios</span><span class="o">.</span><span class="n">tcsetattr</span><span class="p">(</span><span class="n">fd</span><span class="p">,</span> <span class="n">termios</span><span class="o">.</span><span class="n">TCSADRAIN</span><span class="p">,</span> <span class="n">old</span><span class="p">)</span> <span class="k">return</span> <span class="n">passwd</span> </pre></div> </div> </div> </div> </div> </div> </div> <div class="sphinxsidebar"> <div class="sphinxsidebarwrapper"> <h3><a href="../contents.html">Table Of Contents</a></h3> <ul> <li><a class="reference external" href="#">35.7. <tt class="docutils literal"><span class="pre">termios</span></tt> — POSIX style tty control</a><ul> <li><a class="reference external" href="#example">35.7.1. Example</a></li> </ul> </li> </ul> <h4>Previous topic</h4> <p class="topless"><a href="dl.html" title="previous chapter">35.6. <tt class="docutils literal docutils literal docutils literal"><span class="pre">dl</span></tt> — Call C functions in shared objects</a></p> <h4>Next topic</h4> <p class="topless"><a href="tty.html" title="next chapter">35.8. <tt class="docutils literal docutils literal"><span class="pre">tty</span></tt> — Terminal control functions</a></p> <h3>This Page</h3> <ul class="this-page-menu"> <li><a href="../bugs.html">Report a Bug</a></li> <li><a href="../_sources/library/termios.txt" rel="nofollow">Show Source</a></li> </ul> <div id="searchbox" style="display: none"> <h3>Quick search</h3> <form class="search" action="../search.html" method="get"> <input type="text" name="q" size="18" /> <input type="submit" value="Go" /> <input type="hidden" name="check_keywords" value="yes" /> <input type="hidden" name="area" value="default" /> </form> <p class="searchtip" style="font-size: 90%"> Enter search terms or a module, class or function name. </p> </div> <script type="text/javascript">$('#searchbox').show(0);</script> </div> </div> <div class="clearer"></div> </div> <div class="related"> <h3>Navigation</h3> <ul> <li class="right" style="margin-right: 10px"> <a href="../genindex.html" title="General Index" >index</a></li> <li class="right" > <a href="../modindex.html" title="Global Module Index" >modules</a> |</li> <li class="right" > <a href="tty.html" title="35.8. tty — Terminal control functions" >next</a> |</li> <li class="right" > <a href="dl.html" title="35.6. dl — Call C functions in shared objects" >previous</a> |</li> <li><img src="../_static/py.png" alt="" style="vertical-align: middle; margin-top: -1px"/></li> <li><a href="../index.html">Python v2.6.6 documentation</a> »</li> <li><a href="index.html" >The Python Standard Library</a> »</li> <li><a href="unix.html" >35. 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