proc_close

exec

Last updated: Fri, 03 Jul 2009

passthru

(PHP 4, PHP 5)

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 . 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.

Parameters

command: The command that will be executed.
return_var: If the return_var argument is present, the return status of the Unix command will be placed here.

Return Values

No value is returned.

Notes

Warning

When allowing user-supplied data to be passed to this function, use escapeshellarg() or escapeshellcmd() to ensure that users cannot trick the system into executing arbitrary commands.

Note: If a program is started with this function, in order for it to continue running in the background, the output of the program must be redirected to a file or another output stream. Failing to do so will cause PHP to hang until the execution of the program ends.

Note: When safe mode is enabled, you can only execute files within the safe_mode_exec_dir. For practical reasons, it is currently not allowed to have .. components in the path to the executable.

Warning

With safe mode enabled, the command string is escaped with escapeshellcmd(). Thus, echo y | echo x becomes echo y \| echo x.


Stuart:



The pasthru function does not execute the program through the shell.  What this mean, among other things, is that your PATH variable is never set.  Therefore, you have to use full paths on everything.



I believe system() will run your program underneith a shell.  This allow the program to run in a 'normal' environment.



-Paul

nuker at list dot ru
03-Jan-2006 02:51


I wrote function, that gets proxy server value from the Internet Explorer (from

registry). It was tested in Windows XP Pro



(Sorry for my English)



<?php

function getProxyFromIE()

{

        exec("reg query \"HKEY_CURRENT_USER\Software\Microsoft".

        "\Windows\CurrentVersion\Internet Settings\" /v ProxyEnable",

        $proxyenable,$proxyenable_status);



        exec("reg query \"HKEY_CURRENT_USER\Software\Microsoft".

        "\Windows\CurrentVersion\Internet Settings\" /v ProxyServer",

        $proxyserver);



        if($proxyenable_status!=0)

        return false; #Can't access the registry! Very very bad...

        else

        {

        $enabled=substr($proxyenable[4],-1,1);

        if($enabled==0)

        return false;

        else

        {

        $proxy=ereg_replace("^[ \t]{1,10}ProxyServer\tREG_SZ[ \t]{1,20}","",

        $proxyserver[4]);



        if(ereg("[\=\;]",$proxy))

        {

             $proxy=explode(";",$proxy);

             foreach($proxy as $i => $v)

             {

                   if(ereg("http",$v))

                   {

                   $proxy=str_replace("http=","",$v);

                   break;

                   }

             }

             if(@!ereg("^[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\:".

             "[0-9]{1,5}$",$proxy))

             return false;

             else

             return $proxy;

        }

        else

        return $proxy;

        }



        }

}

?>

Note, that this function returns FALSE if proxy is disabled in Internet

Explorer. This function returns ONLY HTTP proxy server.



Usage:

<?php

$proxy=getProxyFromIE();

if(!$proxy)

echo "Can't get proxy!";

else

echo $proxy;

?>

Stuart Eve
08-Dec-2005 08:24


I dunno if anyone else might find this useful, but when I was trying to use the passthru() command on Suse9.3 I was having no success with the command:



$command = 'gdal_translate blahahahaha';



passthru($command);



It only worked once I put:



$command = '/usr/bin/local/gdal_translate blalalala';



passthru($command);

vijayramanan at rediffmail dot com
13-Oct-2005 12:09


I had an issue when i used exec



I think we were echoing information on the test.php script.

for eg: when we tried 



exec(php test.php,$array,$error);



the return was 127 and the code was failing.



checking the note on this page gave us a hint to use passthru instead.

The only thing to note is that you need to provide the fuull path.



now our command became



passthru(/bin/php /pathtotest/test.php,$array,$error);



this works.



yipeee!!!!!

waldow at NOSPAM dot chem dot plu dot edu
22-Sep-2005 04:59


When upgrading my redhat server to enterprise 4, selinux was turned on. This caused one of my php scripts (that uses passthru) to fail.  After some nice help from redhat, I was able to get the script running again. Here is what helped me.



If you get permission errors (in /var/log/httpd/error_log) which seem to be from selinux (and not standard chmod or chown issues), make sure that the folder you are using is not in /tmp and has the selinux context of httpd_sys_script_rw_t as can be set as follows:



chcon -t httpd_sys_script_rw_t folder_name



Hope this helps someone...

stuartc1 at NOSPAM dot hotmail dot com
09-Aug-2005 04:52


Thought it might beuseful to note the passthru seems to supress error messages whilst being run in Dos on Windows (test on NT).



To show FULL raw output including errors, use system().

igor at bboy dot ru
23-Jun-2005 10:33


If you are using passthru() to download files (for dynamically generated content or something outside webserver root) using similar code:



header("Content-Type: application/octet-stream");

header("Content-Disposition: attachment; filename=\"myfile.zip\"");

header("Content-Length: 11111");

passthru("cat myfile.zip",$err);



and your download goes fine, but subsequent downloads / link clicks are screwed up, with headers and binary data being all over the website, try putting



exit();



after the passthrough. This will exit the script after the download is done and will not interfere with any future actions.

sarel dot w at envent dot co dot za
09-Mar-2005 08:33


Zak Estrada

14-Dec-2004 11:21 

Remember to use the full path (IE '/usr/local/bin/foo' instead of 'foo') when using passthru, otherwise you'll get an exit code of 127 (command not found).



Remember, you'll also get this error if your file does not have executable permission.

puppy at cyberpuppy dot org
02-Mar-2005 11:50


Regarding swbrown's comment...you need to use an output buffer if you don't want the data displayed.



For example:

ob_start();

passthru("<i>command</i>");

$var = ob_get_contents();

ob_end_clean(); //Use this instead of ob_flush()



This gets all the output from the command, and exits without sending any data to stdout.

Zak Estrada
14-Dec-2004 05:21


Remember to use the full path (IE '/usr/local/bin/foo' instead of 'foo') when using passthru, otherwise you'll get an exit code of 127 (command not found).

php @ richud dot com
27-May-2004 05:30


Regarding kpierre's post, be mindful that if you shell script errors, you will find the error output from it in the base error_log file (not virtualhost error_log) in apache.

jcr at marvel-databadge dot com
04-Sep-2003 08:23


With apache 2.x on RH9 passthru() writes 1 byte at a time. Apache 2.x buffers and chunk encodes the output for you - but the chunked encoding devides the output in chunks of 1 byte each...thus several bytes of overhead per byte. I guess that buffering behaviour is by design - but caused problems for me with IE adobe acrobot 5 plugin. The plugin doesn't like like it if you send it a stream of 1 byte chunks - it tells you your file is not a pdf or gives a blank screen. Using output buffering (ob_start / ob_endflush) gives reasonable size chunks and the plugin works OK.

swbrown at ucsd dot edu
04-Jun-2003 05:41


passthru() seems absolutely determined to buffer output no matter what you do, even with ob_implicit_flush().  The solution seems to be to use popen() instead.

kpierre at fit dot edu
30-Jan-2002 04:35


The documention does not mention that passthru() will only display standard output and not standard error.



If you are running a script you can pipe the STDERR to STDOUT by doing 



exec 2>&1



Eg. the script below will actually print something with the passthru() function...



#!/bin/sh

exec 2>&1

ulimit -t 60

cat nosuchfile.txt

andreas dot hochsteger at oeamtc dot at
03-Oct-2001 04:51


If you sometimes get no output from passthru() use system() instead. This solved this problem for me (php 4.0.5 on Tru64 Unix compiled with gcc).

sidney at jigsaw dot nl
21-Jun-2001 02:25


PJ's ulimit example is nice; however, if you include multiple commands in the script after the ulimit command, each gets its own, seperate 60 second time slot!<br>





Furthermore, these sixty seconds are *CPU* time. Most programs hang for other reasons than CPU hogging (for example, waiting for a database connection) so for most purposes the number 60 is rather too high.<br>





Try "ulimit -t 1" first, which will give you about 10^9 cycles on modern hardware -- quite enough to get a lot of work done!

PJ at piggei dot com
15-Feb-2001 02:06


About the problem of zombies, you may call a bash script like this:





--------------------------


#! /bin/bash


ulimit -t 60





<your command here>


--------------------------

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