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  5.   <title>Execute an external program and display the output</title>
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  11.  <div class="up"><a href="ref.exec.html">Program execution 函数</a></div>
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  12.  <div class="home"><a href="index.html">PHP Manual</a></div>
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  13. </div><hr /><div id="function.system" class="refentry">
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  14.  <div class="refnamediv">
    15. 

  15.   <h1 class="refname">system</h1>
    16. 

  16.   <p class="verinfo">(PHP 4, PHP 5)</p><p class="refpurpose"><span class="refname">system</span> &mdash; <span class="dc-title">Execute an external program and display the output</span></p>
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  17. 

  18.  </div>
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  19. 

  20.  <div class="refsect1 description" id="refsect1-function.system-description">
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  21.   <h3 class="title">说明</h3>
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  22.   <div class="methodsynopsis dc-description">
    23. 

  23.    <span class="type">string</span> <span class="methodname"><strong>system</strong></span>
    24. 

  24.     ( <span class="methodparam"><span class="type">string</span> <code class="parameter">$command</code></span>
    25. 

  25.    [, <span class="methodparam"><span class="type">int</span> <code class="parameter reference">&$return_var</code></span>
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  26.   ] )</div>
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  27. 

  28.   <p class="para rdfs-comment">
    29. 

  29.     <span class="function"><strong>system()</strong></span> is just like the C version of the
    30. 

  30.    function in that it executes the given
    31. 

  31.    <em><code class="parameter">command</code></em> and outputs the result.
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  32.   </p>
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  33.   <p class="para">
    34. 

  34.    The  <span class="function"><strong>system()</strong></span> call also tries to automatically
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  35.    flush the web server&#039;s output buffer after each line of output if
    36. 

  36.    PHP is running as a server module.
    37. 

  37.   </p>
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  38.   <p class="para">
    39. 

  39.    If you need to execute a command and have all the data from the
    40. 

  40.    command passed directly back without any interference, use the
    41. 

  41.     <span class="function"><a href="function.passthru.html" class="function">passthru()</a></span> function.
    42. 

  42.   </p>
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  43.  </div>
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  44. 

  45. 

  46.  <div class="refsect1 parameters" id="refsect1-function.system-parameters">
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  47.   <h3 class="title">参数</h3>
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  48.   <p class="para">
    49. 

  49.    <dl>
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  50. 

  51.     <dt>
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  52. 

  53.      <span class="term"><em><code class="parameter">command</code></em></span>
    54. 

  54.      <dd>
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  55. 

  56.       <p class="para">
    57. 

  57.        The command that will be executed.
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  58.       </p>
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  59.      </dd>
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  60. 

  61.     </dt>
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  62. 

  63.     <dt>
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  64. 

  65.      <span class="term"><em><code class="parameter">return_var</code></em></span>
    66. 

  66.      <dd>
    67. 

  67. 

  68.       <p class="para">
    69. 

  69.        If the <em><code class="parameter">return_var</code></em> argument is present, then the
    70. 

  70.        return status of the executed command will be written to this
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  71.        variable.
    72. 

  72.       </p>
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  73.      </dd>
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  74. 

  75.     </dt>
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  76. 

  77.    </dl>
    78. 

  78. 

  79.   </p>
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  80.  </div>
    81. 

  81. 

  82. 

  83.  <div class="refsect1 returnvalues" id="refsect1-function.system-returnvalues">
    84. 

  84.   <h3 class="title">返回值</h3>
    85. 

  85.   <p class="para">
    86. 

  86.    Returns the last line of the command output on success, and <strong><code>FALSE</code></strong>
    87. 

  87.    on failure.
    88. 

  88.   </p>
    89. 

  89.  </div>
    90. 

  90. 

  91. 

  92.  <div class="refsect1 examples" id="refsect1-function.system-examples">
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  93.   <h3 class="title">范例</h3>
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  94.   <p class="para">
    95. 

  95.    <div class="example" id="example-3476">
    96. 

  96.     <p><strong>Example #1  <span class="function"><strong>system()</strong></span> example</strong></p>
    97. 

  97.     <div class="example-contents">
    98. 

  98. <div class="phpcode"><code><span style="color: #000000">
    99. 

  99. <span style="color: #0000BB">&lt;?php<br /></span><span style="color: #007700">echo&nbsp;</span><span style="color: #DD0000">'&lt;pre&gt;'</span><span style="color: #007700">;<br /><br /></span><span style="color: #FF8000">//&nbsp;Outputs&nbsp;all&nbsp;the&nbsp;result&nbsp;of&nbsp;shellcommand&nbsp;"ls",&nbsp;and&nbsp;returns<br />//&nbsp;the&nbsp;last&nbsp;output&nbsp;line&nbsp;into&nbsp;$last_line.&nbsp;Stores&nbsp;the&nbsp;return&nbsp;value<br />//&nbsp;of&nbsp;the&nbsp;shell&nbsp;command&nbsp;in&nbsp;$retval.<br /></span><span style="color: #0000BB">$last_line&nbsp;</span><span style="color: #007700">=&nbsp;</span><span style="color: #0000BB">system</span><span style="color: #007700">(</span><span style="color: #DD0000">'ls'</span><span style="color: #007700">,&nbsp;</span><span style="color: #0000BB">$retval</span><span style="color: #007700">);<br /><br /></span><span style="color: #FF8000">//&nbsp;Printing&nbsp;additional&nbsp;info<br /></span><span style="color: #007700">echo&nbsp;</span><span style="color: #DD0000">'<br />&lt;/pre&gt;<br />&lt;hr&nbsp;/&gt;Last&nbsp;line&nbsp;of&nbsp;the&nbsp;output:&nbsp;'&nbsp;</span><span style="color: #007700">.&nbsp;</span><span style="color: #0000BB">$last_line&nbsp;</span><span style="color: #007700">.&nbsp;</span><span style="color: #DD0000">'<br />&lt;hr&nbsp;/&gt;Return&nbsp;value:&nbsp;'&nbsp;</span><span style="color: #007700">.&nbsp;</span><span style="color: #0000BB">$retval</span><span style="color: #007700">;<br /></span><span style="color: #0000BB">?&gt;</span>
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  100. </span>
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  101. </code></div>
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  102.     </div>
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  103. 

  104.    </div>
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  105.   </p>
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  106.  </div>
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  107. 

  108. 

  109.  <div class="refsect1 notes" id="refsect1-function.system-notes">
    110. 

  110.   <h3 class="title">注释</h3>
    111. 

  111.   <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
    112. 

  112.  <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>
    113. 

  113. 来确保用户欺骗系统从而执行任意命令。</p></div>
    114. 

  114.   <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
    115. 

  115. PHP 挂起，直至程序执行结束。</p></p></blockquote>
    116. 

  116.   <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
    117. 

  117. <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>
    118. 

  118.   <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
    119. 

  119.  <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
    120. 

  120. <em>echo y \| echo x</em>。</p></div>
    121. 

  121.  </div>
    122. 

  122. 

  123. 

  124.  <div class="refsect1 seealso" id="refsect1-function.system-seealso">
    125. 

  125.   <h3 class="title">参见</h3>
    126. 

  126.   <p class="para">
    127. 

  127.    <ul class="simplelist">
    128. 

  128.     <li class="member"> <span class="function"><a href="function.exec.html" class="function" rel="rdfs-seeAlso">exec()</a> - Execute an external program</span></li>
    129. 

  129.     <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>
    130. 

  130.     <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>
    131. 

  131.     <li class="member"> <span class="function"><a href="function.escapeshellcmd.html" class="function" rel="rdfs-seeAlso">escapeshellcmd()</a> - Escape shell metacharacters</span></li>
    132. 

  132.     <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>
    133. 

  133.     <li class="member"><a href="language.operators.execution.html" class="link">backtick operator</a></li>
    134. 

  134.    </ul>
    135. 

  135.   </p>
    136. 

  136.  </div>
    137. 

  137. 

  138. </div><hr /><div class="manualnavbar" style="text-align: center;">
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