/php/function.system.html
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- <title>Execute an external program and display the output</title>
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- </div><hr /><div id="function.system" class="refentry">
- <div class="refnamediv">
- <h1 class="refname">system</h1>
- <p class="verinfo">(PHP 4, PHP 5)</p><p class="refpurpose"><span class="refname">system</span> — <span class="dc-title">Execute an external program and display the output</span></p>
- </div>
- <div class="refsect1 description" id="refsect1-function.system-description">
- <h3 class="title">说明</h3>
- <div class="methodsynopsis dc-description">
- <span class="type">string</span> <span class="methodname"><strong>system</strong></span>
- ( <span class="methodparam"><span class="type">string</span> <code class="parameter">$command</code></span>
- [, <span class="methodparam"><span class="type">int</span> <code class="parameter reference">&$return_var</code></span>
- ] )</div>
- <p class="para rdfs-comment">
- <span class="function"><strong>system()</strong></span> is just like the C version of the
- function in that it executes the given
- <em><code class="parameter">command</code></em> and outputs the result.
- </p>
- <p class="para">
- The <span class="function"><strong>system()</strong></span> call also tries to automatically
- flush the web server's output buffer after each line of output if
- PHP is running as a server module.
- </p>
- <p class="para">
- If you need to execute a command and have all the data from the
- command passed directly back without any interference, use the
- <span class="function"><a href="function.passthru.html" class="function">passthru()</a></span> function.
- </p>
- </div>
- <div class="refsect1 parameters" id="refsect1-function.system-parameters">
- <h3 class="title">参数</h3>
- <p class="para">
- <dl>
- <dt>
- <span class="term"><em><code class="parameter">command</code></em></span>
- <dd>
- <p class="para">
- The command that will be executed.
- </p>
- </dd>
- </dt>
- <dt>
- <span class="term"><em><code class="parameter">return_var</code></em></span>
- <dd>
- <p class="para">
- If the <em><code class="parameter">return_var</code></em> argument is present, then the
- return status of the executed command will be written to this
- variable.
- </p>
- </dd>
- </dt>
- </dl>
- </p>
- </div>
- <div class="refsect1 returnvalues" id="refsect1-function.system-returnvalues">
- <h3 class="title">返回值</h3>
- <p class="para">
- Returns the last line of the command output on success, and <strong><code>FALSE</code></strong>
- on failure.
- </p>
- </div>
- <div class="refsect1 examples" id="refsect1-function.system-examples">
- <h3 class="title">范例</h3>
- <p class="para">
- <div class="example" id="example-3476">
- <p><strong>Example #1 <span class="function"><strong>system()</strong></span> example</strong></p>
- <div class="example-contents">
- <div class="phpcode"><code><span style="color: #000000">
- <span style="color: #0000BB"><?php<br /></span><span style="color: #007700">echo </span><span style="color: #DD0000">'<pre>'</span><span style="color: #007700">;<br /><br /></span><span style="color: #FF8000">// Outputs all the result of shellcommand "ls", and returns<br />// the last output line into $last_line. Stores the return value<br />// of the shell command in $retval.<br /></span><span style="color: #0000BB">$last_line </span><span style="color: #007700">= </span><span style="color: #0000BB">system</span><span style="color: #007700">(</span><span style="color: #DD0000">'ls'</span><span style="color: #007700">, </span><span style="color: #0000BB">$retval</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">// Printing additional info<br /></span><span style="color: #007700">echo </span><span style="color: #DD0000">'<br /></pre><br /><hr />Last line of the output: ' </span><span style="color: #007700">. </span><span style="color: #0000BB">$last_line </span><span style="color: #007700">. </span><span style="color: #DD0000">'<br /><hr />Return value: ' </span><span style="color: #007700">. </span><span style="color: #0000BB">$retval</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">?></span>
- </span>
- </code></div>
- </div>
- </div>
- </p>
- </div>
- <div class="refsect1 notes" id="refsect1-function.system-notes">
- <h3 class="title">注释</h3>
- <div class="warning"><strong class="warning">Warning</strong><p class="para">当用户提供的数据传入此函数,使用
- <span class="function"><a href="function.escapeshellarg.html" class="function">escapeshellarg()</a></span> 或 <span class="function"><a href="function.escapeshellcmd.html" class="function">escapeshellcmd()</a></span>
- 来确保用户欺骗系统从而执行任意命令。</p></div>
- <blockquote class="note"><p><strong class="note">Note</strong>: <p class="para">如何程序使用此函数启动,为了能保持在后台运行,此程序必须将输出重定向到文件或其它输出流。否则会导致
- PHP 挂起,直至程序执行结束。</p></p></blockquote>
- <blockquote class="note"><p><strong class="note">Note</strong>: <span class="simpara"><a href="features.safe-mode.html" class="link">安全模式</a> 启用时,可仅可用
- <a href="ini.sect.safe-mode.html#ini.safe-mode-exec-dir" class="link">safe_mode_exec_dir</a> 执行文件。实际上,现在不允许在到可执行的路径中存在 <em>..</em> 组件。</span></p></blockquote>
- <div class="warning"><strong class="warning">Warning</strong><p class="simpara"><a href="features.safe-mode.html" class="link">安全模式</a> 启用时,命令字符串会被
- <span class="function"><a href="function.escapeshellcmd.html" class="function">escapeshellcmd()</a></span> 转换。因此,<em>echo y | echo x</em> 会变成
- <em>echo y \| echo x</em>。</p></div>
- </div>
- <div class="refsect1 seealso" id="refsect1-function.system-seealso">
- <h3 class="title">参见</h3>
- <p class="para">
- <ul class="simplelist">
- <li class="member"> <span class="function"><a href="function.exec.html" class="function" rel="rdfs-seeAlso">exec()</a> - Execute an external program</span></li>
- <li class="member"> <span class="function"><a href="function.passthru.html" class="function" rel="rdfs-seeAlso">passthru()</a> - Execute an external program and display raw output</span></li>
- <li class="member"> <span class="function"><a href="function.popen.html" class="function" rel="rdfs-seeAlso">popen()</a> - 打开进程文件指针</span></li>
- <li class="member"> <span class="function"><a href="function.escapeshellcmd.html" class="function" rel="rdfs-seeAlso">escapeshellcmd()</a> - Escape shell metacharacters</span></li>
- <li class="member"> <span class="function"><a href="function.pcntl-exec.html" class="function" rel="rdfs-seeAlso">pcntl_exec()</a> - 在当前进程空间执行指定程序</span></li>
- <li class="member"><a href="language.operators.execution.html" class="link">backtick operator</a></li>
- </ul>
- </p>
- </div>
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