(PHP 3 <= 3.0.18, PHP 4 >= 4.0.0)
passthru -- Execute an external program and display raw output
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.
| Warning |
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If you are going to allow data coming from user input to be passed to this function, then
you should be using escapeshellarg() or escapeshellcmd() to make sure that users cannot trick the
system into executing arbitrary commands.
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Note: If you start a program using this function and want to leave it running in
the background, you have to make sure that the output of that program is redirected to a file or
some other output stream or else PHP will hang until the execution of the program ends.
See also exec(), system(), popen(), escapeshellcmd(), and the backtick operator.
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