passthru

(PHP 4, PHP 5)

passthru — Ejecuta un programa externo y muestra la salida en bruto

Descripción

void passthru ( string $command [, int &$return_var ] )

La función passthru() es parecida a la función exec() que ejecuta un command. Esta función deberia ser usada en lugar de exec() o system() cuando la salida desde la línea de comandos de Unix sean datos binarios, los cuales sea necesario pasar directamente al navegador. Un uso común para esto, sería para ejecutar algo como las utilidades pbmplus que pueden mostrar directamente una imagen en streaming. Estableciendo el Content-type como image/gif y llamando al programa pbmplus para mostrar un gif, se podrian crear scripts PHP que mostrasen imágenes directamente.

Parámetros

command: El comando que será ejecutado.
return_var: Si está presente el argumento return_var, el valor de retorno de la línea de comandos de Unix será colocado aquí.

Valores devueltos

No devuelve ningún valor.

Notas

Advertencia

Si se va a permitir que datos provenientes del usuario sean enviados a esta función, habría que utilizar escapeshellarg() o escapeshellcmd() para asegurarse que el usuario no intenta engañar al sistema para que ejecute comandos arbitrarios.

Nota:
Si ejecutamos un programa con esta función y queremos dejarlo ejecutándose en segundo plano, hay que asegurarse que la salida del mismo es redireccionada a un fichero u otro flujo de salida o PHP se quedará esperando hasta que la ejecución del programa termine.

Nota: Cuando safe mode está habilitado, sólo se pueden ejecutar los archivos que se encuentren dentro de safe_mode_exec_dir. Por razones prácticas, actualmente no se le permite tener componentes .. en la ruta al ejecutable.

Advertencia

Con safe mode habilitado, la cadena de comandos se escapa con escapeshellcmd(). Por esto, echo y | echo x quedaría echo y \| echo x.

Ver también

exec() - Ejecutar un programa externo
system() - Ejecutar un programa externo y mostrar su salida
popen() - Abre un proceso de un puntero a un fichero
escapeshellcmd() - Escapar meta-caracteres del intérprete de comandos
backtick operator

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User Contributed Notes 19 notes

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igor at bboy dot ru ¶

9 years ago


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.

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Chroot ¶

6 years ago


If you have chrooted apache and php, you will also want to put /bin/sh into the chrooted environment. Otherwise, the exec() or passthru() will not function properly, and will produce error code 127, file not found.

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myselfasunder at gmail dot com dot dfvuks ¶

3 years ago


PHP's program-execution commands fail miserably when it comes to STDERR, and the proc_open() command doesn't work all that consistently in non-blocking mode under Windows.

This command, although useful, is no different. To form a mechanism that will see/capture both STDOUT and STDERR output, pipe the command to the 'tee' command (which can be found for Windows), and wrap the whole thing in output buffering.

Dustin Oprea

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andreas dot hochsteger at oeamtc dot at ¶

12 years ago


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).

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jo at durchholz dot org ¶

6 years ago


Note to Paul Giblock: the command *is* run through the shell.
You can verify this on any Linux system with

<?php
passthru ('echo $PATH');
?>

You'll get the content of the PATH environment variable, not the string $PATH.

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stuartc1 at NOSPAM dot hotmail dot com ¶

8 years ago


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().

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swbrown at ucsd dot edu ¶

11 years ago


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.

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sidney at jigsaw dot nl ¶

13 years ago


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!

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Stuart Eve ¶

8 years ago


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);

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vijayramanan at rediffmail dot com ¶

8 years ago


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!!!!!

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sarel dot w at envent dot co dot za ¶

9 years ago


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.

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puppy at cyberpuppy dot org ¶

9 years ago


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.

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php @ richud dot com ¶

10 years ago


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.

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jcr at marvel-databadge dot com ¶

10 years ago


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.

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kpierre at fit dot edu ¶

12 years ago


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

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PJ at piggei dot com ¶

13 years ago


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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-1

nuker at list dot ru ¶

8 years ago


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;
?>

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-1

Paul Giblock ¶

7 years ago


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

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-1

Zak Estrada ¶

9 years ago


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).

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