uTools-Manuals/docs/python/posix.html

<div class="body" role="main"><div class="section" id="module-posix"><h1><span class="yiyi-st" id="yiyi-10">35.1. <a class="reference internal" href="#module-posix" title="posix: The most common POSIX system calls (normally used via module os). (Unix)"><code class="xref py py-mod docutils literal"><span class="pre">posix</span></code></a>  - 最常见的POSIX系统调用</span></h1><p><span class="yiyi-st" id="yiyi-11">此模块提供对由C标准和POSIX标准（一个伪装的Unix接口）标准化的操作系统功能的访问。</span></p><p id="index-0"><span class="yiyi-st" id="yiyi-12"><strong>不要直接导入此模块。</strong></span><span class="yiyi-st" id="yiyi-13">请改为导入模块<a class="reference internal" href="os.html#module-os" title="os: Miscellaneous operating system interfaces."><code class="xref py py-mod docutils literal"><span class="pre">os</span></code></a>，该模块提供此界面的<em>便携式</em>版本。</span><span class="yiyi-st" id="yiyi-14">在Unix上，<a class="reference internal" href="os.html#module-os" title="os: Miscellaneous operating system interfaces."><code class="xref py py-mod docutils literal"><span class="pre">os</span></code></a>模块提供<a class="reference internal" href="#module-posix" title="posix: The most common POSIX system calls (normally used via module os). (Unix)"><code class="xref py py-mod docutils literal"><span class="pre">posix</span></code></a>接口的超集。</span><span class="yiyi-st" id="yiyi-15">在非Unix操作系统上，<a class="reference internal" href="#module-posix" title="posix: The most common POSIX system calls (normally used via module os). (Unix)"><code class="xref py py-mod docutils literal"><span class="pre">posix</span></code></a>模块不可用，但通过<a class="reference internal" href="os.html#module-os" title="os: Miscellaneous operating system interfaces."><code class="xref py py-mod docutils literal"><span class="pre">os</span></code></a>接口始终可以使用子集。</span><span class="yiyi-st" id="yiyi-16">导入<a class="reference internal" href="os.html#module-os" title="os: Miscellaneous operating system interfaces."><code class="xref py py-mod docutils literal"><span class="pre">os</span></code></a>后，使用它而不是<a class="reference internal" href="#module-posix" title="posix: The most common POSIX system calls (normally used via module os). (Unix)"><code class="xref py py-mod docutils literal"><span class="pre">posix</span></code></a>时，存在<em>没有</em>性能损失。</span><span class="yiyi-st" id="yiyi-17">此外，<a class="reference internal" href="os.html#module-os" title="os: Miscellaneous operating system interfaces."><code class="xref py py-mod docutils literal"><span class="pre">os</span></code></a>提供了一些额外的功能，例如当<code class="docutils literal"><span class="pre">os.environ</span></code>中的条目更改时自动调用<a class="reference internal" href="os.html#os.putenv" title="os.putenv"><code class="xref py py-func docutils literal"><span class="pre">putenv()</span></code></a></span></p><p><span class="yiyi-st" id="yiyi-18">错误报告为异常；对类型错误给出通常的异常，而由系统报告的错误调用引发<a class="reference internal" href="exceptions.html#OSError" title="OSError"><code class="xref py py-exc docutils literal"><span class="pre">OSError</span></code></a>。</span></p><div class="section" id="large-file-support"><h2><span class="yiyi-st" id="yiyi-19">35.1.1. </span><span class="yiyi-st" id="yiyi-20">Large File Support</span></h2><p id="index-1"><span class="yiyi-st" id="yiyi-21">对于<code class="xref c c-type docutils literal"><span class="pre">int</span></code>和<code class="xref c c-type docutils literal"><span class="pre">long</span></code>的C编程模型，多个操作系统（包括AIX，HP-UX，Irix和Solaris）支持大于2 GiB的文件位值。</span><span class="yiyi-st" id="yiyi-22">这通常通过将相关大小和偏移类型定义为64位值来实现。</span><span class="yiyi-st" id="yiyi-23">此类文件有时称为<em class="dfn">大文件</em>。</span></p><p><span class="yiyi-st" id="yiyi-24">当<code class="xref c c-type docutils literal"><span class="pre">off_t</span></code>的大小大于<code class="xref c c-type docutils literal"><span class="pre">long</span></code>和<code class="xref c c-type docutils literal"><span class="pre">长</span> <span class="pre">长时，在Python中启用大文件支持。 / t6&gt;</span></code>类型可用，并且至少与<code class="xref c c-type docutils literal"><span class="pre">off_t</span></code>一样大。</span><span class="yiyi-st" id="yiyi-25">可能需要使用某些编译器标志来配置和编译Python以启用此模式。</span><span class="yiyi-st" id="yiyi-26">例如，默认情况下，它使用最新版本的Irix启用，但是对于Solaris 2.6和2.7，您需要执行以下操作：</span></p><pre><code class="language-python"><span></span><span class="n">CFLAGS</span><span class="o">=</span><span class="s2">"`getconf LFS_CFLAGS`"</span> <span class="n">OPT</span><span class="o">=</span><span class="s2">"-g -O2 $CFLAGS"</span> \
        <span class="o">./</span><span class="n">configure</span>
</code></pre><p><span class="yiyi-st" id="yiyi-27">在大型文件的Linux系统上，这可能工作：</span></p><pre><code class="language-python"><span></span><span class="n">CFLAGS</span><span class="o">=</span><span class="s1">'-D_LARGEFILE64_SOURCE -D_FILE_OFFSET_BITS=64'</span> <span class="n">OPT</span><span class="o">=</span><span class="s2">"-g -O2 $CFLAGS"</span> \
        <span class="o">./</span><span class="n">configure</span>
</code></pre></div><div class="section" id="notable-module-contents"><h2><span class="yiyi-st" id="yiyi-28">35.1.2.注释模块内容</span></h2><p><span class="yiyi-st" id="yiyi-29">除了<a class="reference internal" href="os.html#module-os" title="os: Miscellaneous operating system interfaces."><code class="xref py py-mod docutils literal"><span class="pre">os</span></code></a>模块文档中描述的许多函数，<a class="reference internal" href="#module-posix" title="posix: The most common POSIX system calls (normally used via module os). (Unix)"><code class="xref py py-mod docutils literal"><span class="pre">posix</span></code></a>定义了以下数据项：</span></p><dl class="data"><dt id="posix.environ"><span class="yiyi-st" id="yiyi-30"> <code class="descclassname">posix.</code><code class="descname">environ</code></span></dt><dd><p><span class="yiyi-st" id="yiyi-31">表示解释器启动时的字符串环境的字典。</span><span class="yiyi-st" id="yiyi-32">键和值是Unix和str上的字节。</span><span class="yiyi-st" id="yiyi-33">例如，在Windows上的<code class="docutils literal"><span class="pre">environ[b'HOME']</span></code>（<code class="docutils literal"><span class="pre">environ['HOME']</span></code>）是您的主目录的路径名，相当于<code class="docutils literal"><span class="pre">getenv("HOME")</span></code>。</span></p><p><span class="yiyi-st" id="yiyi-34">修改此字典不会影响<a class="reference internal" href="os.html#os.execv" title="os.execv"><code class="xref py py-func docutils literal"><span class="pre">execv()</span></code></a>，<a class="reference internal" href="os.html#os.popen" title="os.popen"><code class="xref py py-func docutils literal"><span class="pre">popen()</span></code></a>或<a class="reference internal" href="os.html#os.system" title="os.system"><code class="xref py py-func docutils literal"><span class="pre">system()</span></code></a>传递的字符串环境；如果您需要更改环境，请将<code class="docutils literal"><span class="pre">environ</span></code>传递给<a class="reference internal" href="os.html#os.execve" title="os.execve"><code class="xref py py-func docutils literal"><span class="pre">execve()</span></code></a>或将变量分配和导出语句添加到<a class="reference internal" href="os.html#os.system" title="os.system"><code class="xref py py-func docutils literal"><span class="pre">system()</span></code></a>或<a class="reference internal" href="os.html#os.popen" title="os.popen"><code class="xref py py-func docutils literal"><span class="pre">popen()</span></code></a>。</span></p><div class="versionchanged"><p><span class="yiyi-st" id="yiyi-35"><span class="versionmodified">在版本3.2中更改：</span>在Unix上，键和值是字节。</span></p></div><div class="admonition note"><p class="first admonition-title"><span class="yiyi-st" id="yiyi-36">注意</span></p><p class="last"><span class="yiyi-st" id="yiyi-37"><a class="reference internal" href="os.html#module-os" title="os: Miscellaneous operating system interfaces."><code class="xref py py-mod docutils literal"><span class="pre">os</span></code></a>模块提供了<code class="docutils literal"><span class="pre">environ</span></code>的替代实现，它在修改时更新环境。</span><span class="yiyi-st" id="yiyi-38">还要注意，更新<a class="reference internal" href="os.html#os.environ" title="os.environ"><code class="xref py py-data docutils literal"><span class="pre">os.environ</span></code></a>会使此字典过时。</span><span class="yiyi-st" id="yiyi-39">建议使用<a class="reference internal" href="os.html#module-os" title="os: Miscellaneous operating system interfaces."><code class="xref py py-mod docutils literal"><span class="pre">os</span></code></a>模块版本，直接访问<a class="reference internal" href="#module-posix" title="posix: The most common POSIX system calls (normally used via module os). (Unix)"><code class="xref py py-mod docutils literal"><span class="pre">posix</span></code></a>模块。</span></p></div></dd></dl></div></div></div>