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><H1
><A
NAME="function.passthru"
></A
>passthru</H1
><DIV
CLASS="refnamediv"
><A
NAME="AEN188958"
></A
><P
> (PHP 3, PHP 4, PHP 5)</P
>passthru -- Execute an external program and display raw output</DIV
><DIV
CLASS="refsect1"
><A
NAME="AEN188961"
></A
><H2
>说明</H2
>void <B
CLASS="methodname"
>passthru</B
> ( string command [, int &return_var] )<BR
></BR
><P
> The <B
CLASS="function"
>passthru()</B
> function is similar to the
<A
HREF="function.exec.html"
><B
CLASS="function"
>exec()</B
></A
> function in that it executes a
<CODE
CLASS="parameter"
>command</CODE
>. This function
should be used in place of <A
HREF="function.exec.html"
><B
CLASS="function"
>exec()</B
></A
> or
<A
HREF="function.system.html"
><B
CLASS="function"
>system()</B
></A
> when the output from the Unix command
is binary data which needs to be passed directly back to the
browser. A common use for this is to execute something like the
pbmplus utilities that can output an image stream directly. By
setting the Content-type to <SPAN
CLASS="emphasis"
><I
CLASS="emphasis"
>image/gif</I
></SPAN
> and
then calling a pbmplus program to output a gif, you can create
PHP scripts that output images directly.
</P
></DIV
><DIV
CLASS="refsect1"
><A
NAME="AEN188979"
></A
><H2
>参数</H2
><P
> <P
></P
><DIV
CLASS="variablelist"
><DL
><DT
><CODE
CLASS="parameter"
>command</CODE
></DT
><DD
><P
> The command that will be executed.
</P
></DD
><DT
><CODE
CLASS="parameter"
>return_var</CODE
></DT
><DD
><P
> If the <CODE
CLASS="parameter"
>return_var</CODE
> argument is present, the
return status of the Unix command will be placed here.
</P
></DD
></DL
></DIV
>
</P
></DIV
><DIV
CLASS="refsect1"
><A
NAME="AEN188994"
></A
><H2
>返回值</H2
><P
> 无返回值。
</P
></DIV
><DIV
CLASS="refsect1"
><A
NAME="AEN188997"
></A
><H2
>注释</H2
><DIV
CLASS="warning"
><P
></P
><TABLE
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><TR
><TD
ALIGN="CENTER"
><B
>警告</B
></TD
></TR
><TR
><TD
ALIGN="LEFT"
><P
>如果想允许用户输入的数据被传入本函数，则应使用
<A
HREF="function.escapeshellarg.html"
><B
CLASS="function"
>escapeshellarg()</B
></A
> 或 <A
HREF="function.escapeshellcmd.html"
><B
CLASS="function"
>escapeshellcmd()</B
></A
>
函数来确保用户不能欺骗系统从而执行任意命令。</P
></TD
></TR
></TABLE
></DIV
><DIV
CLASS="note"
><BLOCKQUOTE
CLASS="note"
><P
><B
>注意: </B
>如果用本函数启动一个程序并希望保持在后台运行，必须确保该程序的输出被重定向到一个文件或者其它输出流去，否则
PHP 会在程序执行结束前挂起。</P
></BLOCKQUOTE
></DIV
><DIV
CLASS="note"
><BLOCKQUOTE
CLASS="note"
><P
><B
>注意: </B
>在打开了<A
HREF="features.safe-mode.html"
>安全模式</A
>时，只能执行在
<A
HREF="features.safe-mode.html#ini.safe-mode-exec-dir"
>safe_mode_exec_dir</A
>
之内的程序。为实用起见目前不能在指向程序的路径中包含
<TT
CLASS="literal"
>..</TT
> 成分。</P
></BLOCKQUOTE
></DIV
><DIV
CLASS="warning"
><P
></P
><TABLE
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><TR
><TD
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><B
>警告</B
></TD
></TR
><TR
><TD
ALIGN="LEFT"
><P
>在打开了<A
HREF="features.safe-mode.html"
>安全模式</A
>时，命令字符串会被 <A
HREF="function.escapeshellcmd.html"
><B
CLASS="function"
>escapeshellcmd()</B
></A
>
转义。从而 <TT
CLASS="literal"
>echo y | echo x</TT
> 就成了 <TT
CLASS="literal"
>echo "y | echo x"</TT
>。</P
></TD
></TR
></TABLE
></DIV
></DIV
><DIV
CLASS="refsect1"
><A
NAME="AEN189016"
></A
><H2
>参见</H2
><P
> <P
></P
><TABLE
BORDER="0"
><TBODY
><TR
><TD
><A
HREF="function.exec.html"
><B
CLASS="function"
>exec()</B
></A
></TD
></TR
><TR
><TD
><A
HREF="function.system.html"
><B
CLASS="function"
>system()</B
></A
></TD
></TR
><TR
><TD
><A
HREF="function.popen.html"
><B
CLASS="function"
>popen()</B
></A
></TD
></TR
><TR
><TD
><A
HREF="function.escapeshellcmd.html"
><B
CLASS="function"
>escapeshellcmd()</B
></A
></TD
></TR
><TR
><TD
><A
HREF="language.operators.execution.html"
>backtick operator</A
></TD
></TR
></TBODY
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><P
></P
>
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