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https://github.com/sigmasternchen/php-doc-en
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git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@137984 c90b9560-bf6c-de11-be94-00142212c4b1
106 lines
3.4 KiB
XML
106 lines
3.4 KiB
XML
<?xml version="1.0" encoding="iso-8859-1"?>
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<!-- $Revision: 1.3 $ -->
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<!-- splitted from ./en/functions/exec.xml, last change in rev 1.24 -->
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<refentry id="function.system">
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<refnamediv>
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<refname>system</refname>
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<refpurpose>Execute an external program and display output</refpurpose>
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</refnamediv>
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<refsect1>
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<title>Description</title>
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<methodsynopsis>
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<type>string</type><methodname>system</methodname>
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<methodparam><type>string</type><parameter>command</parameter></methodparam>
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<methodparam choice="opt"><type>int</type><parameter>return_var</parameter></methodparam>
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</methodsynopsis>
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<para>
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<function>system</function> is just like the C version of the
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function in that it executes the given
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<parameter>command</parameter> and outputs the result. If a
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variable is provided as the second argument, then the return
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status code of the executed command will be written to this
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variable.
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</para>
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<warning>
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<para>
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If you are going to allow data coming from user input to be passed to
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this function, then you should be using
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<function>escapeshellarg</function> or
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<function>escapeshellcmd</function> to make sure that users cannot trick
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the system into executing arbitrary commands.
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</para>
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</warning>
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<note>
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<para>
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If you start a program using this function and want to leave it running
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in the background, you have to make sure that the output of that program
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is redirected to a file or some other output stream or else PHP will
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hang until the execution of the program ends.
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</para>
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</note>
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<para>
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The <function>system</function> call also tries to automatically
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flush the web server's output buffer after each line of output if
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PHP is running as a server module.
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</para>
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<para>
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Returns the last line of the command output on success, and &false;
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on failure.
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</para>
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<para>
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If you need to execute a command and have all the data from the
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command passed directly back without any interference, use the
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<function>passthru</function> function.
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</para>
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<para>
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<example>
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<title><function>system</function> example</title>
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<programlisting role="php">
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<![CDATA[
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<?php
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echo '<pre>';
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// Outputs all the result of shellcommand "ls", and returns
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// the last output line into $last_line. Stores the return value
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// of the shell command in $retval.
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$last_line = system('ls', $retval);
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// Printing additional info
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echo '
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</pre>
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<hr>Last line of the output: '.$last_line.'
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<hr>Return value: '.$retval;
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?>
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]]>
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</programlisting>
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</example>
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</para>
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<para>
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See also <function>exec</function>,
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<function>passthru</function>, <function>popen</function>,
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<function>escapeshellcmd</function>, and the <link
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linkend="language.operators.execution">backtick operator</link>.
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</para>
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</refsect1>
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</refentry>
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<!-- Keep this comment at the end of the file
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Local variables:
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mode: sgml
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sgml-omittag:t
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sgml-shorttag:t
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sgml-minimize-attributes:nil
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sgml-always-quote-attributes:t
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sgml-indent-step:1
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sgml-indent-data:t
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indent-tabs-mode:nil
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sgml-parent-document:nil
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sgml-default-dtd-file:"../../../../manual.ced"
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sgml-exposed-tags:nil
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sgml-local-catalogs:nil
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sgml-local-ecat-files:nil
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End:
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vim600: syn=xml fen fdm=syntax fdl=2 si
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vim: et tw=78 syn=sgml
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vi: ts=1 sw=1
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-->
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