exec
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.
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 archivo
- escapeshellcmd() - Escapar meta-caracteres del intérprete de comandos
- backtick operator
add a note
User Contributed Notes
passthru - [21 notes]
igor at bboy dot ru ¶
7 years ago
Chroot ¶
4 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.
jo at durchholz dot org ¶
5 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.
nuker at list dot ru ¶
7 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 $proxy;
?>
vijayramanan at rediffmail dot com ¶
7 years ago
I had an issue when i used exec
I think we were echoing information on the test.php script.
for eg: when we tried
exec(php test.php,$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!!!!!
waldow at NOSPAM dot chem dot plu dot edu ¶
7 years ago
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...
myselfasunder at gmail dot com dot dfvuks ¶
2 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
ignacio paz posse ¶
3 years ago
I'd like to refer about the use of use of passthru as a substitute to include or require which I didn't see before. It helped me to workaround a problem with a script which fatally failed only when included or required. I presume that it had to be with recursive includes because there where memory exhaustion messages that didn't get fixed even when increasing the memory limit with ini_set(). As I had no time to re-code it, the fix of the problem was to get the output of the script via a passthru call.
Something like this:
<?php
# ...
# (function stuff)
ob_start();
passthru("php myscript.php, $result");
$content_grabbed=ob_get_contents();
ob_end_clean();
if($result=0){
echo '<div>',$content_grabbed,'</div>';
}_
# (more function stuff)
# ...
?>
I don't know about drawbacks that this method might have. Maybe and increased overhead? Anyway I was happy to circumvent the problem with it.
Paul Giblock ¶
6 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
Stuart Eve ¶
7 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);
stuartc1 at NOSPAM dot hotmail dot com ¶
7 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().
sarel dot w at envent dot co dot za ¶
8 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.
puppy at cyberpuppy dot org ¶
8 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.
Zak Estrada ¶
8 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).
php @ richud dot com ¶
9 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.
jcr at marvel-databadge dot com ¶
9 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.
swbrown at ucsd dot edu ¶
10 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.
kpierre at fit dot edu ¶
11 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
andreas dot hochsteger at oeamtc dot at ¶
11 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).
sidney at jigsaw dot nl ¶
11 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!
PJ at piggei dot com ¶
12 years ago
About the problem of zombies, you may call a bash script like this:
--------------------------
#! /bin/bash
ulimit -t 60
<your command here>
--------------------------