Server : Apache
System : Linux server1.cgrithy.com 3.10.0-1160.95.1.el7.x86_64 #1 SMP Mon Jul 24 13:59:37 UTC 2023 x86_64
User : nobody ( 99)
PHP Version : 8.1.23
Disable Function : NONE
Directory : /usr/share/doc/python-docs-2.7.5/html/library/
|
Server : Apache System : Linux server1.cgrithy.com 3.10.0-1160.95.1.el7.x86_64 #1 SMP Mon Jul 24 13:59:37 UTC 2023 x86_64 User : nobody ( 99) PHP Version : 8.1.23 Disable Function : NONE Directory : /usr/share/doc/python-docs-2.7.5/html/library/ |
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>35.11. pipes — Interface to shell pipelines — Python 2.7.5 documentation</title>
<link rel="stylesheet" href="../_static/default.css" type="text/css" />
<link rel="stylesheet" href="../_static/pygments.css" type="text/css" />
<script type="text/javascript">
var DOCUMENTATION_OPTIONS = {
URL_ROOT: '../',
VERSION: '2.7.5',
COLLAPSE_INDEX: false,
FILE_SUFFIX: '.html',
HAS_SOURCE: true
};
</script>
<script type="text/javascript" src="../_static/jquery.js"></script>
<script type="text/javascript" src="../_static/underscore.js"></script>
<script type="text/javascript" src="../_static/doctools.js"></script>
<script type="text/javascript" src="../_static/sidebar.js"></script>
<link rel="search" type="application/opensearchdescription+xml"
title="Search within Python 2.7.5 documentation"
href="../_static/opensearch.xml"/>
<link rel="author" title="About these documents" href="../about.html" />
<link rel="copyright" title="Copyright" href="../copyright.html" />
<link rel="top" title="Python 2.7.5 documentation" href="../index.html" />
<link rel="up" title="35. Unix Specific Services" href="unix.html" />
<link rel="next" title="35.12. posixfile — File-like objects with locking support" href="posixfile.html" />
<link rel="prev" title="35.10. fcntl — The fcntl() and ioctl() system calls" href="fcntl.html" />
<link rel="shortcut icon" type="image/png" href="../_static/py.png" />
<script type="text/javascript" src="../_static/copybutton.js"></script>
</head>
<body>
<div class="related">
<h3>Navigation</h3>
<ul>
<li class="right" style="margin-right: 10px">
<a href="../genindex.html" title="General Index"
accesskey="I">index</a></li>
<li class="right" >
<a href="../py-modindex.html" title="Python Module Index"
>modules</a> |</li>
<li class="right" >
<a href="posixfile.html" title="35.12. posixfile — File-like objects with locking support"
accesskey="N">next</a> |</li>
<li class="right" >
<a href="fcntl.html" title="35.10. fcntl — The fcntl() and ioctl() system calls"
accesskey="P">previous</a> |</li>
<li><img src="../_static/py.png" alt=""
style="vertical-align: middle; margin-top: -1px"/></li>
<li><a href="http://www.python.org/">Python</a> »</li>
<li>
<a href="../index.html">Python 2.7.5 documentation</a> »
</li>
<li><a href="index.html" >The Python Standard Library</a> »</li>
<li><a href="unix.html" accesskey="U">35. Unix Specific Services</a> »</li>
</ul>
</div>
<div class="document">
<div class="documentwrapper">
<div class="bodywrapper">
<div class="body">
<div class="section" id="module-pipes">
<span id="pipes-interface-to-shell-pipelines"></span><h1>35.11. <a class="reference internal" href="#module-pipes" title="pipes: A Python interface to Unix shell pipelines. (Unix)"><tt class="xref py py-mod docutils literal"><span class="pre">pipes</span></tt></a> — Interface to shell pipelines<a class="headerlink" href="#module-pipes" title="Permalink to this headline">¶</a></h1>
<p><strong>Source code:</strong> <a class="reference external" href="http://hg.python.org/cpython/file/2.7/Lib/pipes.py">Lib/pipes.py</a></p>
<hr class="docutils" />
<p>The <a class="reference internal" href="#module-pipes" title="pipes: A Python interface to Unix shell pipelines. (Unix)"><tt class="xref py py-mod docutils literal"><span class="pre">pipes</span></tt></a> module defines a class to abstract the concept of a <em>pipeline</em>
— a sequence of converters from one file to another.</p>
<p>Because the module uses <strong class="program">/bin/sh</strong> command lines, a POSIX or compatible
shell for <a class="reference internal" href="os.html#os.system" title="os.system"><tt class="xref py py-func docutils literal"><span class="pre">os.system()</span></tt></a> and <a class="reference internal" href="os.html#os.popen" title="os.popen"><tt class="xref py py-func docutils literal"><span class="pre">os.popen()</span></tt></a> is required.</p>
<dl class="class">
<dt id="pipes.Template">
<em class="property">class </em><tt class="descclassname">pipes.</tt><tt class="descname">Template</tt><a class="headerlink" href="#pipes.Template" title="Permalink to this definition">¶</a></dt>
<dd><p>An abstraction of a pipeline.</p>
</dd></dl>
<p>Example:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="kn">import</span> <span class="nn">pipes</span>
<span class="gp">>>> </span><span class="n">t</span> <span class="o">=</span> <span class="n">pipes</span><span class="o">.</span><span class="n">Template</span><span class="p">()</span>
<span class="gp">>>> </span><span class="n">t</span><span class="o">.</span><span class="n">append</span><span class="p">(</span><span class="s">'tr a-z A-Z'</span><span class="p">,</span> <span class="s">'--'</span><span class="p">)</span>
<span class="gp">>>> </span><span class="n">f</span> <span class="o">=</span> <span class="n">t</span><span class="o">.</span><span class="n">open</span><span class="p">(</span><span class="s">'pipefile'</span><span class="p">,</span> <span class="s">'w'</span><span class="p">)</span>
<span class="gp">>>> </span><span class="n">f</span><span class="o">.</span><span class="n">write</span><span class="p">(</span><span class="s">'hello world'</span><span class="p">)</span>
<span class="gp">>>> </span><span class="n">f</span><span class="o">.</span><span class="n">close</span><span class="p">()</span>
<span class="gp">>>> </span><span class="nb">open</span><span class="p">(</span><span class="s">'pipefile'</span><span class="p">)</span><span class="o">.</span><span class="n">read</span><span class="p">()</span>
<span class="go">'HELLO WORLD'</span>
</pre></div>
</div>
<dl class="function">
<dt id="pipes.quote">
<tt class="descclassname">pipes.</tt><tt class="descname">quote</tt><big>(</big><em>s</em><big>)</big><a class="headerlink" href="#pipes.quote" title="Permalink to this definition">¶</a></dt>
<dd><p class="deprecated">
<span class="versionmodified">Deprecated since version 1.6: </span>Prior to Python 2.7, this function was not publicly documented. It is
finally exposed publicly in Python 3.3 as the
<tt class="xref py py-func docutils literal"><span class="pre">quote</span></tt> function in the <a class="reference internal" href="shlex.html#module-shlex" title="shlex: Simple lexical analysis for Unix shell-like languages."><tt class="xref py py-mod docutils literal"><span class="pre">shlex</span></tt></a> module.</p>
<p>Return a shell-escaped version of the string <em>s</em>. The returned value is a
string that can safely be used as one token in a shell command line, for
cases where you cannot use a list.</p>
<p>This idiom would be unsafe:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="n">filename</span> <span class="o">=</span> <span class="s">'somefile; rm -rf ~'</span>
<span class="gp">>>> </span><span class="n">command</span> <span class="o">=</span> <span class="s">'ls -l {}'</span><span class="o">.</span><span class="n">format</span><span class="p">(</span><span class="n">filename</span><span class="p">)</span>
<span class="gp">>>> </span><span class="k">print</span> <span class="n">command</span> <span class="c"># executed by a shell: boom!</span>
<span class="go">ls -l somefile; rm -rf ~</span>
</pre></div>
</div>
<p><a class="reference internal" href="#pipes.quote" title="pipes.quote"><tt class="xref py py-func docutils literal"><span class="pre">quote()</span></tt></a> lets you plug the security hole:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="n">command</span> <span class="o">=</span> <span class="s">'ls -l {}'</span><span class="o">.</span><span class="n">format</span><span class="p">(</span><span class="n">quote</span><span class="p">(</span><span class="n">filename</span><span class="p">))</span>
<span class="gp">>>> </span><span class="k">print</span> <span class="n">command</span>
<span class="go">ls -l 'somefile; rm -rf ~'</span>
<span class="gp">>>> </span><span class="n">remote_command</span> <span class="o">=</span> <span class="s">'ssh home {}'</span><span class="o">.</span><span class="n">format</span><span class="p">(</span><span class="n">quote</span><span class="p">(</span><span class="n">command</span><span class="p">))</span>
<span class="gp">>>> </span><span class="k">print</span> <span class="n">remote_command</span>
<span class="go">ssh home 'ls -l '"'"'somefile; rm -rf ~'"'"''</span>
</pre></div>
</div>
<p>The quoting is compatible with UNIX shells and with <a class="reference internal" href="shlex.html#shlex.split" title="shlex.split"><tt class="xref py py-func docutils literal"><span class="pre">shlex.split()</span></tt></a>:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="n">remote_command</span> <span class="o">=</span> <span class="n">shlex</span><span class="o">.</span><span class="n">split</span><span class="p">(</span><span class="n">remote_command</span><span class="p">)</span>
<span class="gp">>>> </span><span class="n">remote_command</span>
<span class="go">['ssh', 'home', "ls -l 'somefile; rm -rf ~'"]</span>
<span class="gp">>>> </span><span class="n">command</span> <span class="o">=</span> <span class="n">shlex</span><span class="o">.</span><span class="n">split</span><span class="p">(</span><span class="n">remote_command</span><span class="p">[</span><span class="o">-</span><span class="mi">1</span><span class="p">])</span>
<span class="gp">>>> </span><span class="n">command</span>
<span class="go">['ls', '-l', 'somefile; rm -rf ~']</span>
</pre></div>
</div>
</dd></dl>
<div class="section" id="template-objects">
<span id="id1"></span><h2>35.11.1. Template Objects<a class="headerlink" href="#template-objects" title="Permalink to this headline">¶</a></h2>
<p>Template objects following methods:</p>
<dl class="method">
<dt id="pipes.Template.reset">
<tt class="descclassname">Template.</tt><tt class="descname">reset</tt><big>(</big><big>)</big><a class="headerlink" href="#pipes.Template.reset" title="Permalink to this definition">¶</a></dt>
<dd><p>Restore a pipeline template to its initial state.</p>
</dd></dl>
<dl class="method">
<dt id="pipes.Template.clone">
<tt class="descclassname">Template.</tt><tt class="descname">clone</tt><big>(</big><big>)</big><a class="headerlink" href="#pipes.Template.clone" title="Permalink to this definition">¶</a></dt>
<dd><p>Return a new, equivalent, pipeline template.</p>
</dd></dl>
<dl class="method">
<dt id="pipes.Template.debug">
<tt class="descclassname">Template.</tt><tt class="descname">debug</tt><big>(</big><em>flag</em><big>)</big><a class="headerlink" href="#pipes.Template.debug" title="Permalink to this definition">¶</a></dt>
<dd><p>If <em>flag</em> is true, turn debugging on. Otherwise, turn debugging off. When
debugging is on, commands to be executed are printed, and the shell is given
<tt class="docutils literal"><span class="pre">set</span> <span class="pre">-x</span></tt> command to be more verbose.</p>
</dd></dl>
<dl class="method">
<dt id="pipes.Template.append">
<tt class="descclassname">Template.</tt><tt class="descname">append</tt><big>(</big><em>cmd</em>, <em>kind</em><big>)</big><a class="headerlink" href="#pipes.Template.append" title="Permalink to this definition">¶</a></dt>
<dd><p>Append a new action at the end. The <em>cmd</em> variable must be a valid bourne shell
command. The <em>kind</em> variable consists of two letters.</p>
<p>The first letter can be either of <tt class="docutils literal"><span class="pre">'-'</span></tt> (which means the command reads its
standard input), <tt class="docutils literal"><span class="pre">'f'</span></tt> (which means the commands reads a given file on the
command line) or <tt class="docutils literal"><span class="pre">'.'</span></tt> (which means the commands reads no input, and hence
must be first.)</p>
<p>Similarly, the second letter can be either of <tt class="docutils literal"><span class="pre">'-'</span></tt> (which means the command
writes to standard output), <tt class="docutils literal"><span class="pre">'f'</span></tt> (which means the command writes a file on
the command line) or <tt class="docutils literal"><span class="pre">'.'</span></tt> (which means the command does not write anything,
and hence must be last.)</p>
</dd></dl>
<dl class="method">
<dt id="pipes.Template.prepend">
<tt class="descclassname">Template.</tt><tt class="descname">prepend</tt><big>(</big><em>cmd</em>, <em>kind</em><big>)</big><a class="headerlink" href="#pipes.Template.prepend" title="Permalink to this definition">¶</a></dt>
<dd><p>Add a new action at the beginning. See <a class="reference internal" href="#pipes.Template.append" title="pipes.Template.append"><tt class="xref py py-meth docutils literal"><span class="pre">append()</span></tt></a> for explanations of the
arguments.</p>
</dd></dl>
<dl class="method">
<dt id="pipes.Template.open">
<tt class="descclassname">Template.</tt><tt class="descname">open</tt><big>(</big><em>file</em>, <em>mode</em><big>)</big><a class="headerlink" href="#pipes.Template.open" title="Permalink to this definition">¶</a></dt>
<dd><p>Return a file-like object, open to <em>file</em>, but read from or written to by the
pipeline. Note that only one of <tt class="docutils literal"><span class="pre">'r'</span></tt>, <tt class="docutils literal"><span class="pre">'w'</span></tt> may be given.</p>
</dd></dl>
<dl class="method">
<dt id="pipes.Template.copy">
<tt class="descclassname">Template.</tt><tt class="descname">copy</tt><big>(</big><em>infile</em>, <em>outfile</em><big>)</big><a class="headerlink" href="#pipes.Template.copy" title="Permalink to this definition">¶</a></dt>
<dd><p>Copy <em>infile</em> to <em>outfile</em> through the pipe.</p>
</dd></dl>
</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 internal" href="#">35.11. <tt class="docutils literal"><span class="pre">pipes</span></tt> — Interface to shell pipelines</a><ul>
<li><a class="reference internal" href="#template-objects">35.11.1. Template Objects</a></li>
</ul>
</li>
</ul>
<h4>Previous topic</h4>
<p class="topless"><a href="fcntl.html"
title="previous chapter">35.10. <tt class="docutils literal"><span class="pre">fcntl</span></tt> — The <tt class="docutils literal"><span class="pre">fcntl()</span></tt> and <tt class="docutils literal"><span class="pre">ioctl()</span></tt> system calls</a></p>
<h4>Next topic</h4>
<p class="topless"><a href="posixfile.html"
title="next chapter">35.12. <tt class="docutils literal"><span class="pre">posixfile</span></tt> — File-like objects with locking support</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/pipes.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" />
<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="../py-modindex.html" title="Python Module Index"
>modules</a> |</li>
<li class="right" >
<a href="posixfile.html" title="35.12. posixfile — File-like objects with locking support"
>next</a> |</li>
<li class="right" >
<a href="fcntl.html" title="35.10. fcntl — The fcntl() and ioctl() system calls"
>previous</a> |</li>
<li><img src="../_static/py.png" alt=""
style="vertical-align: middle; margin-top: -1px"/></li>
<li><a href="http://www.python.org/">Python</a> »</li>
<li>
<a href="../index.html">Python 2.7.5 documentation</a> »
</li>
<li><a href="index.html" >The Python Standard Library</a> »</li>
<li><a href="unix.html" >35. Unix Specific Services</a> »</li>
</ul>
</div>
<div class="footer">
© <a href="../copyright.html">Copyright</a> 1990-2020, Python Software Foundation.
<br />
The Python Software Foundation is a non-profit corporation.
<a href="http://www.python.org/psf/donations/">Please donate.</a>
<br />
Last updated on Oct 13, 2020.
<a href="../bugs.html">Found a bug</a>?
<br />
Created using <a href="http://sphinx.pocoo.org/">Sphinx</a> 1.1.3.
</div>
</body>
</html>