<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <html> <head> <link rel="STYLESHEET" href="lib.css" type='text/css' /> <link rel="SHORTCUT ICON" href="../icons/pyfav.gif" /> <link rel='start' href='../index.html' title='Python Documentation Index' /> <link rel="first" href="lib.html" title='Python Library Reference' /> <link rel='contents' href='contents.html' title="Contents" /> <link rel='index' href='genindex.html' title='Index' /> <link rel='last' href='about.html' title='About this document...' /> <link rel='help' href='about.html' title='About this document...' /> <LINK rel="next" href="module-os.path.html"> <LINK rel="prev" href="allos.html"> <LINK rel="parent" href="allos.html"> <LINK rel="next" href="os-procinfo.html"> <meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" /> <meta name='aesop' content='information' /> <META name="description" content="os -- Miscellaneous operating system interfaces"> <META name="keywords" content="lib"> <META name="resource-type" content="document"> <META name="distribution" content="global"> <title>6.1 os -- Miscellaneous operating system interfaces</title> </head> <body> <DIV CLASS="navigation"> <div id='top-navigation-panel'> <table align="center" width="100%" cellpadding="0" cellspacing="2"> <tr> <td class='online-navigation'><a rel="prev" title="6. 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Generic Operating System</A> <b class="navlabel">Up:</b> <a class="sectref" rel="parent" href="allos.html">6. Generic Operating System</A> <b class="navlabel">Next:</b> <a class="sectref" rel="next" href="os-procinfo.html">6.1.1 Process Parameters</A> </div> <hr /></div> </DIV> <!--End of Navigation Panel--> <H1><A NAME="SECTION008100000000000000000"> 6.1 <tt class="module">os</tt> -- Miscellaneous operating system interfaces</A> </H1> <P> <A NAME="module-os"><!--z--></A> <P> This module provides a more portable way of using operating system dependent functionality than importing a operating system dependent built-in module like <tt class="module"><a href="module-posix.html">posix</a></tt> or <tt class="module">nt</tt>. <P> This module searches for an operating system dependent built-in module like <tt class="module">mac</tt> or <tt class="module"><a href="module-posix.html">posix</a></tt> and exports the same functions and data as found there. The design of all Python's built-in operating system dependent modules is such that as long as the same functionality is available, it uses the same interface; for example, the function <code>os.stat(<var>path</var>)</code> returns stat information about <var>path</var> in the same format (which happens to have originated with the POSIX interface). <P> Extensions peculiar to a particular operating system are also available through the <tt class="module">os</tt> module, but using them is of course a threat to portability! <P> Note that after the first time <tt class="module">os</tt> is imported, there is <i>no</i> performance penalty in using functions from <tt class="module">os</tt> instead of directly from the operating system dependent built-in module, so there should be <i>no</i> reason not to use <tt class="module">os</tt>! <P> The <tt class="module">os</tt> module contains many functions and data values. The items below and in the following sub-sections are all available directly from the <tt class="module">os</tt> module. <P> <dl><dt><b><span class="typelabel">exception</span> <tt id='l2h-1335' class="exception">error</tt></b></dt> <dd> This exception is raised when a function returns a system-related error (not for illegal argument types or other incidental errors). This is also known as the built-in exception <tt class="exception">OSError</tt>. The accompanying value is a pair containing the numeric error code from <tt class="cdata">errno</tt> and the corresponding string, as would be printed by the C function <tt class="cfunction">perror()</tt>. See the module <tt class="module"><a href="module-errno.html">errno</a></tt><a id='l2h-1338'><!--x--></a>, which contains names for the error codes defined by the underlying operating system. <P> When exceptions are classes, this exception carries two attributes, <tt class="member">errno</tt> and <tt class="member">strerror</tt>. The first holds the value of the C <tt class="cdata">errno</tt> variable, and the latter holds the corresponding error message from <tt class="cfunction">strerror()</tt>. For exceptions that involve a file system path (such as <tt class="function">chdir()</tt> or <tt class="function">unlink()</tt>), the exception instance will contain a third attribute, <tt class="member">filename</tt>, which is the file name passed to the function. </dd></dl> <P> <dl><dt><b><tt id='l2h-1336'>name</tt></b></dt> <dd> The name of the operating system dependent module imported. The following names have currently been registered: <code>'posix'</code>, <code>'nt'</code>, <code>'mac'</code>, <code>'os2'</code>, <code>'ce'</code>, <code>'java'</code>, <code>'riscos'</code>. </dd></dl> <P> <dl><dt><b><tt id='l2h-1337'>path</tt></b></dt> <dd> The corresponding operating system dependent standard module for pathname operations, such as <tt class="module">posixpath</tt> or <tt class="module">macpath</tt>. Thus, given the proper imports, <code>os.path.split(<var>file</var>)</code> is equivalent to but more portable than <code>posixpath.split(<var>file</var>)</code>. Note that this is also an importable module: it may be imported directly as <tt class="module"><a href="module-os.path.html">os.path</a></tt>. </dd></dl> <P> <p><br /></p><hr class='online-navigation' /> <div class='online-navigation'> <!--Table of Child-Links--> <A NAME="CHILD_LINKS"><STRONG>Subsections</STRONG></a> <UL CLASS="ChildLinks"> <LI><A href="os-procinfo.html">6.1.1 Process Parameters</a> <LI><A href="os-newstreams.html">6.1.2 File Object Creation</a> <LI><A href="os-fd-ops.html">6.1.3 File Descriptor Operations</a> <LI><A href="os-file-dir.html">6.1.4 Files and Directories</a> <LI><A href="os-process.html">6.1.5 Process Management</a> <LI><A href="os-path.html">6.1.6 Miscellaneous System Information</a> </ul> <!--End of Table of Child-Links--> </div> <DIV CLASS="navigation"> <div class='online-navigation'><hr /> <table align="center" width="100%" cellpadding="0" cellspacing="2"> <tr> <td class='online-navigation'><a rel="prev" title="6. 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