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<li><a class="reference internal" href="#">getpass – Prompt the user for a password without echoing.</a><ul>
<li><a class="reference internal" href="#example">Example</a></li>
<li><a class="reference internal" href="#using-getpass-without-a-terminal">Using getpass Without a Terminal</a></li>
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<div class="section" id="module-getpass">
<span id="getpass-prompt-the-user-for-a-password-without-echoing"></span><h1>getpass – Prompt the user for a password without echoing.<a class="headerlink" href="#module-getpass" title="Permalink to this headline">¶</a></h1>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field"><th class="field-name">Purpose:</th><td class="field-body">Prompt the user for a value, usually a password, without echoing what they type to the console.</td>
</tr>
<tr class="field"><th class="field-name">Python Version:</th><td class="field-body">1.5.2</td>
</tr>
</tbody>
</table>
<p>Many programs that interact with the user via the terminal need to ask
the user for password values without showing what the user types on
the screen. The <a class="reference internal" href="#module-getpass" title="getpass: Prompt the user for a value, usually a password, without echoing what they type to the console."><tt class="xref py py-mod docutils literal"><span class="pre">getpass</span></tt></a> module provides a portable way to
handle such password prompts securely.</p>
<div class="section" id="example">
<h2>Example<a class="headerlink" href="#example" title="Permalink to this headline">¶</a></h2>
<p>The <a class="reference internal" href="#module-getpass" title="getpass: Prompt the user for a value, usually a password, without echoing what they type to the console."><tt class="xref py py-func docutils literal"><span class="pre">getpass()</span></tt></a> function prints a prompt then reads input from
the user until they press return. The input is passed back as a string
to the caller.</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">import</span> <span class="nn">getpass</span>
<span class="n">p</span> <span class="o">=</span> <span class="n">getpass</span><span class="o">.</span><span class="n">getpass</span><span class="p">()</span>
<span class="k">print</span> <span class="s">'You entered:'</span><span class="p">,</span> <span class="n">p</span>
</pre></div>
</div>
<p>The default prompt, if none is specified by the caller, is
“<tt class="docutils literal"><span class="pre">Password:</span></tt>”.</p>
<div class="highlight-python"><pre>$ python getpass_defaults.py
Password:
You entered: sekret</pre>
</div>
<p>The prompt can be changed to any value your program needs.</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">import</span> <span class="nn">getpass</span>
<span class="n">p</span> <span class="o">=</span> <span class="n">getpass</span><span class="o">.</span><span class="n">getpass</span><span class="p">(</span><span class="n">prompt</span><span class="o">=</span><span class="s">'What is your favorite color? '</span><span class="p">)</span>
<span class="k">if</span> <span class="n">p</span><span class="o">.</span><span class="n">lower</span><span class="p">()</span> <span class="o">==</span> <span class="s">'blue'</span><span class="p">:</span>
<span class="k">print</span> <span class="s">'Right. Off you go.'</span>
<span class="k">else</span><span class="p">:</span>
<span class="k">print</span> <span class="s">'Auuuuugh!'</span>
</pre></div>
</div>
<p>I don’t recommend such an insecure authentication scheme, but it illustrates
the point.</p>
<div class="highlight-python"><pre>$ python getpass_prompt.py
What is your favorite color?
Right. Off you go.
$ python getpass_prompt.py
What is your favorite color?
Auuuuugh!</pre>
</div>
<p>By default, <a class="reference internal" href="#module-getpass" title="getpass: Prompt the user for a value, usually a password, without echoing what they type to the console."><tt class="xref py py-func docutils literal"><span class="pre">getpass()</span></tt></a> uses stdout to print the prompt
string. For a program which may produce useful output on
<a class="reference internal" href="../sys/runtime.html#sys-input-output"><em>sys.stdout</em></a>, it is frequently better to send
the prompt to another stream such as <a class="reference internal" href="../sys/runtime.html#sys-input-output"><em>sys.stderr</em></a>.</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">import</span> <span class="nn">getpass</span>
<span class="kn">import</span> <span class="nn">sys</span>
<span class="n">p</span> <span class="o">=</span> <span class="n">getpass</span><span class="o">.</span><span class="n">getpass</span><span class="p">(</span><span class="n">stream</span><span class="o">=</span><span class="n">sys</span><span class="o">.</span><span class="n">stderr</span><span class="p">)</span>
<span class="k">print</span> <span class="s">'You entered:'</span><span class="p">,</span> <span class="n">p</span>
</pre></div>
</div>
<p>This way standard output can be redirected (to a pipe or file) without seeing
the password prompt. The value entered by the user is still not echoed back to
the screen.</p>
<div class="highlight-python"><pre>$ python getpass_stream.py >/dev/null
Password:</pre>
</div>
</div>
<div class="section" id="using-getpass-without-a-terminal">
<h2>Using getpass Without a Terminal<a class="headerlink" href="#using-getpass-without-a-terminal" title="Permalink to this headline">¶</a></h2>
<p>Under Unix, <a class="reference internal" href="#module-getpass" title="getpass: Prompt the user for a value, usually a password, without echoing what they type to the console."><tt class="xref py py-func docutils literal"><span class="pre">getpass()</span></tt></a> always requires a tty it can control via
termios, so echo can be disabled. This means values will not be read
from a non-terminal stream redirected to standard input.</p>
<div class="highlight-python"><pre>$ echo "sekret" | python getpass_defaults.py
Traceback (most recent call last):
File "getpass_defaults.py", line 34, in
p = getpass.getpass()
File "/Library/Frameworks/Python.framework/Versions/2.5/lib/python2.5/getpass.py", line 32, in unix_getpass
old = termios.tcgetattr(fd) # a copy to save
termios.error: (25, 'Inappropriate ioctl for device')</pre>
</div>
<p>It is up to the caller to detect when the input stream is not a tty and use an
alternate method for reading in that case.</p>
<div class="highlight-python"><div class="highlight"><pre><span class="kn">import</span> <span class="nn">getpass</span>
<span class="kn">import</span> <span class="nn">sys</span>
<span class="k">if</span> <span class="n">sys</span><span class="o">.</span><span class="n">stdin</span><span class="o">.</span><span class="n">isatty</span><span class="p">():</span>
<span class="n">p</span> <span class="o">=</span> <span class="n">getpass</span><span class="o">.</span><span class="n">getpass</span><span class="p">(</span><span class="s">'Using getpass: '</span><span class="p">)</span>
<span class="k">else</span><span class="p">:</span>
<span class="k">print</span> <span class="s">'Using readline'</span>
<span class="n">p</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">readline</span><span class="p">()</span><span class="o">.</span><span class="n">rstrip</span><span class="p">()</span>
<span class="k">print</span> <span class="s">'Read: '</span><span class="p">,</span> <span class="n">p</span>
</pre></div>
</div>
<p>With a tty:</p>
<div class="highlight-python"><pre>$ python ./getpass_noterminal.py
Using getpass:
Read: sekret</pre>
</div>
<p>Without a tty:</p>
<div class="highlight-python"><pre>$ echo "sekret" | python ./getpass_noterminal.py
Using readline
Read: sekret</pre>
</div>
<div class="admonition-see-also admonition seealso">
<p class="first admonition-title">See also</p>
<dl class="last docutils">
<dt><a class="reference external" href="http://docs.python.org/library/getpass.html">getpass</a></dt>
<dd>The standard library documentation for this module.</dd>
<dt><a class="reference internal" href="../readline/index.html#module-readline" title="readline: Interface to the GNU readline library"><tt class="xref py py-mod docutils literal"><span class="pre">readline</span></tt></a></dt>
<dd>Interactive prompt library.</dd>
</dl>
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