Description
void
passthru ( string command [, int return_var])
The passthru() function is similar to the
exec() function in that it executes a
command. If the
return_var argument is present, the return
status of the Unix command will be placed here. This function
should be used in place of exec() or
system() 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 image/gif and
then calling a pbmplus program to output a gif, you can create
PHP scripts that output images directly.
注: 如果你用此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 会在程序执行结束后挂起。
警告 |
在打开了安全模式时,任何初始命令字符串之后的词都被看成一个单一的参数。因此,echo
y | echo x 就成了 echo "y | echo x"。 |
See also exec(), system(),
popen(), escapeshellcmd(),
and the backtick
operator.