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proc_open

(PHP 4 >= 4.3.0, PHP 5)

proc_open Ejecuta un comando y abre un puntero de fichero para entrada/salida

Descripción

resource proc_open ( string $cmd , array $descriptorspec , array &$pipes [, string $cwd [, array $env [, array $other_options ]]] )

proc_open() es similar a popen() pero provee un grado de control mucho más grande sobre la ejecución del programa.

Parámetros

cmd

El comando a ejecutar

descriptorspec

Un array indexado donde la clave representa el número descriptor y el valor representa como PHP pasará que descriptor para que proceso hijo. 0 es stdin, 1 es stdout, 2 es stderr.

Cada elemento puede ser:

  • Un array que describe la tubería que se va a pasar al proceso. El primer elemento es el tipo de descriptor, y el segundo elemento es una opción para el tipo dado. Los tipos válidos son: pipe (en este caso el segundo elemento sería r para pasar a leer el final de la tubería para el proceso, o w para pasar a escribir al final) y file (en este caso el segundo elemento sería el nombre de fichero).
  • Un recurso de flujo representando un descriptor de un fichero real (p.e. un fichero abierto, un socket, STDIN).

Los números descriptores de fichero no estan limitados a 0, 1 y 2. Se puede especificar cualquier número descriptor válido de fichero, y este ser pasado al proceso hijo. Esto permite a su script para inteoperar con otros scripts que corren como "co-procesos". En particular esto es útil pasando passphrases para programas como PGP, GPG y OpenSSL de una manera más segura. Esto es útil también para la lectura de la información del estado provista por estos programas en descriptores de fichero auxiliares.

pipes

En un array indexado es establecerán los punteros de fichero que se corresponden con el fin de cualquier tuberia PHP que se haya creado.

cwd

El directorio inicial de trabajo para el comando. Este debe ser una ruta absoluta, o si se prefiere puede ser NULL si se desea usar el valor por defecto (entonces será el directorio de trabajo del proceso PHP en curso)

env

Un array con las variables de entorno para el comando que será ejecutado, o NULL para usar el mismo entorno como el del proceso PHP en curso.

other_options

Permite especificar opciones adicionales. Actualmente las opciones soportadas incluidas son:

  • suppress_errors (solo windows): suprime errores generados por esta función cuando es establece en TRUE
  • bypass_shell (solo windows): Desvia en la consola de cmd.exe cuando se establece en TRUE

Valores devueltos

Devuelve un recurso representando el proceso, cuando se haya terminado con él, deberá ser liberado usandoproc_close(). En caso de error devuelve FALSE.

Historial de cambios

Versión Descripción
5.2.1 Añadida la opción bypass_shell al parámetro other_options.
5.0.0 Añadidos los parámetros cwd, env y other_options.

Ejemplos

Ejemplo #1 Ejemplo de proc_open()

<?php
$descriptorspec 
= array(
   
=> array("pipe""r"),  // stdin es una tubería usada por el hijo para lectura
   
=> array("pipe""w"),  // stdout es una tubería usada por el hijo para escritura
   
=> array("file""/tmp/error-output.txt""a"// stderr es un fichero para escritura
);

$cwd '/tmp';
$env = array('some_option' => 'aeiou');

$process proc_open('php'$descriptorspec$pipes$cwd$env);

if (
is_resource($process)) {
    
// $pipes ahora será algo como:
    // 0 => gestor de escritura conectado al stdin hijo
    // 1 => gestor de lectura conectado al stdout hijo
    // Cualquier error de salida será anexado a /tmp/error-output.txt

    
fwrite($pipes[0], '<?php print_r($_ENV); ?>');
    
fclose($pipes[0]);

    echo 
"--".stream_get_contents($pipes[1])."--";
    
fclose($pipes[1]);

    
// Es importante que se cierren todas las tubería antes de llamar a
    // proc_close para evitar así un punto muerto
    
$return_value proc_close($process);

    echo 
"command returned $return_value\n";
}
?>

El resultado del ejemplo sería algo similar a:

Array
(
    [some_option] => aeiou
    [PWD] => /tmp
    [SHLVL] => 1
    [_] => /usr/local/bin/php
)
command returned 0

Notas

Nota:

Compatibilidad con Windows: Los descriptores por encima de 2 (stderr) se ponen a disposición del proceso hijo como gestores heredables, pero desde la arquitectura de Windows no se asocia el número descriptor de fichero con los gestores de bajo nivel. El proceso hijo (todavia) no tiene un medio de acceso a estos gestores. Stdin, stdout and stderr funcionan como se esperaba.

Nota:

Si solamente se necesita una tubería de proceso unidireccional, es mejor usar popen() en su lugar, ya que es mucho más fácil de utilizar.

Ver también

  • popen() - Abre un proceso de un puntero a un fichero
  • exec() - Ejecutar un programa externo
  • system() - Ejecutar un programa externo y mostrar su salida
  • passthru() - Ejecuta un programa externo y muestra la salida en bruto
  • stream_select() - Ejecuta el equivalente de la llamada al sistema select() sobre las matrices de flujos dadas con un tiempo de espera especificado por tv_sec y tv_usec
  • The backtick operator

add a note add a note

User Contributed Notes 40 notes

up
3
mattis at xait dot no
3 years ago
If you are, like me, tired of the buggy way proc_open handles streams and exit codes; this example demonstrate the power of pcntl, posix and some simple output redirection:

<?php
$outpipe
= '/tmp/outpipe';
$inpipe = '/tmp/inpipe';
posix_mkfifo($inpipe, 0600);
posix_mkfifo($outpipe, 0600);

$pid = pcntl_fork();

//parent
if($pid) {
   
$in = fopen($inpipe, 'w');
   
fwrite($in, "A message for the inpipe reader\n");
   
fclose($in);
   
   
$out = fopen($outpipe, 'r');
    while(!
feof($out)) {
        echo
"From out pipe: " . fgets($out) . PHP_EOL;
    }
   
fclose($out);

   
pcntl_waitpid($pid, $status);
   
    if(
pcntl_wifexited($status)) {
        echo
"Reliable exit code: " . pcntl_wexitstatus($status) . PHP_EOL;
    }
   
   
unlink($outpipe);
   
unlink($inpipe);
}

//child
else {
   
//parent
   
if($pid = pcntl_fork()) {
       
pcntl_exec('/bin/sh', array('-c', "printf 'A message for the outpipe reader' > $outpipe 2>&1 && exit 12"));
    }
   
   
//child
   
else {
       
pcntl_exec('/bin/sh', array('-c', "printf 'From in pipe: '; cat $inpipe"));
    }   
}
?>

Output:

From in pipe: A message for the inpipe reader
From out pipe: A message for the outpipe reader
Reliable exit code: 12
up
3
daniela at itconnect dot net dot au
11 years ago
Just a small note in case it isn't obvious, its possible to treat the filename as in fopen, thus you can pass through the standard input from php like
    $descs = array (
                0 => array ("file", "php://stdin", "r"),
                1 => array ("pipe", "w"),
                2 => array ("pipe", "w")
        );
        $proc = proc_open ("myprogram", $descs, $fp);
up
5
Luceo
4 years ago
It seems that stream_get_contents() on STDOUT blocks infinitly under Windows when STDERR is filled under some circumstances.

The trick is to open STDERR in append mode ("a"), then this will work, too.

<?php
$descriptorspec
= array(
   
0 => array('pipe', 'r'), // stdin
   
1 => array('pipe', 'w'), // stdout
   
2 => array('pipe', 'a') // stderr
);
?>
up
2
chris AT w3style DOT co.uk
6 years ago
It took me a long time (and three consecutive projects) to figure this out.  Because popen() and proc_open() return valid processes even when the command failed it's awkward to determine when it really has failed if you're opening a non-interactive process like "sendmail -t".

I had previously guess that reading from STDERR immediately after starting the process would work, and it does... but when the command is successful PHP just hangs because STDERR is empty and it's waiting for data to be written to it.

The solution is a simple stream_set_blocking($pipes[2], 0) immediately after calling proc_open().

<?php

    $this
->_proc = proc_open($command, $descriptorSpec, $pipes);
   
stream_set_blocking($pipes[2], 0);
    if (
$err = stream_get_contents($pipes[2]))
    {
      throw new
Swift_Transport_TransportException(
       
'Process could not be started [' . $err . ']'
       
);
    }

?>

If the process is opened successfully $pipes[2] will be empty, but if it failed the bash/sh error will be in it.

Finally I can drop all my "workaround" error checking.

I realise this solution is obvious and I'm not sure how it took me 18 months to figure it out, but hopefully this will help someone else.

NOTE: Make sure your descriptorSpec has ( 2 => array('pipe', 'w')) for this to work.
up
2
exel at example dot com
10 months ago
pipe communications may break brains off. i want to share some stuff to avoid such result.
for proper control of the communications through the "in" and "out" pipes of the opened sub-process, remember to set both of them into non-blocking mode and especially notice that fwrite may return (int)0 but it's not an error, just process might not except input at that moment.

so, let us consider an example of decoding gz-encoded file by using funzip as sub-process: (this is not the final version, just to show important things)

<?php
           
// make gz file
           
$fd=fopen("/tmp/testPipe", "w");
            for(
$i=0;$i<100000;$i++)
               
fwrite($fd, md5($i)."\n");
           
fclose($fd);

            if(
is_file("/tmp/testPipe.gz"))
               
unlink("/tmp/testPipe.gz");
           
system("gzip /tmp/testPipe");

           
// open process
           
$pipesDescr=array(
               
0 => array("pipe", "r"),
               
1 => array("pipe", "w"),
               
2 => array("file", "/tmp/testPipe.log", "a"),
            );

           
$process=proc_open("zcat", $pipesDescr, $pipes);
            if(!
is_resource($process)) throw new Exception("popen error");

           
// set both pipes non-blocking
           
stream_set_blocking($pipes[0], 0);
           
stream_set_blocking($pipes[1], 0);

           
////////////////////////////////////////////////////////////////////

           
$text="";
           
$fd=fopen("/tmp/testPipe.gz", "r");
            while(!
feof($fd))
            {
               
$str=fread($fd, 16384*4);
               
$try=3;
                while(
$str)
                {
                   
$len=fwrite($pipes[0], $str);
                    while(
$s=fread($pipes[1], 16384*4))
                       
$text.=$s;

                    if(!
$len)
                    {
                       
// if yo remove this paused retries, process may fail
                       
usleep(200000);
                       
$try--;
                        if(!
$try)
                            throw new
Exception("fwrite error");
                    }
                   
$str=substr($str, $len);
                }
                echo
strlen($text)."\n";
            }
           
fclose($fd);
           
fclose($pipes[0]);

           
// reading the rest of output stream
           
stream_set_blocking($pipes[1], 1);
            while(!
feof($pipes[1]))
            {
               
$s=fread($pipes[1], 16384);
               
$text.=$s;
            }

            echo
strlen($text)." / 3 300 000\n";
?>
up
2
michael dot gross at NOSPAM dot flexlogic dot at
1 year ago
Please note that if you plan to spawn multiple processes you have to save all the results in different variables (in an array for example). If you for example would call $proc = proc_open..... multiple times the script will block after the second time until the child process exits (proc_close is called implicitly).
up
2
John Wehin
6 years ago
STDIN STDOUT example
test.php

<?php
$descriptorspec
= array(
  
0 => array("pipe", "r"),
  
1 => array("pipe", "w"),
  
2 => array("pipe", "r")
);
$process = proc_open('php test_gen.php', $descriptorspec, $pipes, null, null); //run test_gen.php
echo ("Start process:\n");
if (
is_resource($process))
{
   
fwrite($pipes[0], "start\n");    // send start
   
echo ("\n\nStart ....".fgets($pipes[1],4096)); //get answer
   
fwrite($pipes[0], "get\n");    // send get
   
echo ("Get: ".fgets($pipes[1],4096));    //get answer
   
fwrite($pipes[0], "stop\n");    //send stop
   
echo ("\n\nStop ....".fgets($pipes[1],4096));  //get answer

   
fclose($pipes[0]);
   
fclose($pipes[1]);
   
fclose($pipes[2]);
   
$return_value = proc_close($process);  //stop test_gen.php
   
echo ("Returned:".$return_value."\n");
}
?>

test_gen.php
<?php
$keys
=0;
function
play_stop()
{
global
$keys;
       
$stdin_stat_arr=fstat(STDIN);
        if(
$stdin_stat_arr[size]!=0)
        {
           
$val_in=fread(STDIN,4096);
            switch(
$val_in)
            {
            case
"start\n":    echo "Started\n";
                    return
false;
                    break;
            case
"stop\n":    echo "Stopped\n";
                   
$keys=0;
                    return
false;
                    break;
            case
"pause\n":    echo "Paused\n";
                    return
false;
                    break;
            case
"get\n":    echo ($keys."\n");
                    return
true;
                    break;
            default:    echo(
"Передан не верный параметр: ".$val_in."\n");
                    return
true;
                    exit();
            }
        }else{return
true;}
}
while(
true)
{
while(
play_stop()){usleep(1000);}
while(
play_stop()){$keys++;usleep(10);}
}
?>
up
2
Kyle Gibson
9 years ago
proc_open is hard coded to use "/bin/sh". So if you're working in a chrooted environment, you need to make sure that /bin/sh exists, for now.
up
1
sergioshev at gmail dot com
8 days ago
If you want make use of double pipe. As prove of concept something like this...

"Double pipe example."
cat in_data | cat | cat > out_data

here is an example how to achieve that

<?php

$d2
= array (
 
0 => array('pipe','r'),
 
1 => array('file','/var/tmp/test_gen_trans.log','w')
);

$proc_2 = proc_open('cat', $d2, $p2);

$d = array(
 
0 => array('file','/var/tmp/test.log','r'),
 
1 => $p2[0]
);

$proc = proc_open("cat", $d, $p);
proc_close($proc);
proc_close($proc_2);

?>
up
1
devel at romanr dot info
2 years ago
The call works as should. No bugs.
But. In most cases you won't able to work with pipes in blocking mode.
When your output pipe (process' input one, $pipes[0]) is blocking, there is a case, when you and the process are blocked on output.
When your input pipe (process' output one, $pipes[1]) is blocking, there is a case, when you and the process both are blocked on own input.
So you should switch pipes into NONBLOCKING mode (stream_set_blocking).
Then, there is a case, when you're not able to read anything (fread($pipes[1],...) == "") either write (fwrite($pipes[0],...) == 0). In this case, you better check the process is alive (proc_get_status) and if it still is - wait for some time (stream_select). The situation is truly asynchronous, the process may be busy working, processing your data.
Using shell effectively makes not possible to know whether the command is exists - proc_open always returns valid resource. You may even write some data into it (into shell, actually). But eventually it will terminate, so check the process status regularly.
I would advice not using mkfifo-pipes, because filesystem fifo-pipe (mkfifo) blocks open/fopen call (!!!) until somebody opens other side (unix-related behavior). In case the pipe is opened not by shell and the command is crashed or is not exists you will be blocked forever.
up
1
radone at gmail dot com
6 years ago
To complete the examples below that use proc_open to encrypt a string using GPG, here is a decrypt function:

<?php
function gpg_decrypt($string, $secret) {
   
$homedir = ''; // path to you gpg keyrings
   
$tmp_file = '/tmp/gpg_tmp.asc' ; // tmp file to write to       
   
file_put_contents($tmp_file, $string);

   
$text = '';
   
$error = '';
   
$descriptorspec = array(
       
0 => array("pipe", "r"),  // stdin
       
1 => array("pipe", "w"),  // stdout
       
2 => array("pipe", "w")   // stderr ?? instead of a file
       
);
   
$command = 'gpg --homedir ' . $homedir . ' --batch --no-verbose --passphrase-fd 0 -d ' . $tmp_file . ' ';
   
$process = proc_open($command, $descriptorspec, $pipes);
    if (
is_resource($process)) {
       
fwrite($pipes[0], $secret);
       
fclose($pipes[0]);
        while(
$s= fgets($pipes[1], 1024)) {
         
// read from the pipe
         
$text .= $s;
        }
       
fclose($pipes[1]);
       
// optional:
       
while($s= fgets($pipes[2], 1024)) {
         
$error .= $s . "\n";
        }
       
fclose($pipes[2]);
    }
           
   
file_put_contents($tmp_file, '');
   
    if (
preg_match('/decryption failed/i', $error)) {
        return
false;
    } else {
        return
$text;
    }
}
?>
up
1
Anonymous
6 years ago
I needed to emulate a tty for a process (it wouldnt write to stdout or read from stdin), so I found this:

<?php
$descriptorspec
= array(0 => array('pty'),
                       
1 => array('pty'),
                       
2 => array('pty')); 
?>

pipes are bidirectional then
up
1
php dot net_manual at reimwerker dot de
8 years ago
If you are going to allow data coming from user input to be passed to this function, then you should keep in mind the following warning that also applies to exec() and system():

http://www.php.net/manual/en/function.exec.php
http://www.php.net/manual/en/function.system.php

Warning:

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.
up
1
mib at post dot com
9 years ago
I thought it was highly not recommended to fork from your web server?

Apart from that, one caveat is that the child process inherits anything that is preserved over fork from the parent (apart from the file descriptors which are explicitly closed).

Importantly, it inherits the signal handling setup, which at least with apache means that SIGPIPE is ignored.  Child processes that expect SIGPIPE to kill them in order to get sensible pipe handling and not go into a tight write loop will have problems unless they reset SIGPIPE themselves.

Similar caveats probably apply to other signals like SIGHUP, SIGINT, etc.

Other things preserved over fork include shared memory segments, umask and rlimits.
up
0
mcuadros at gmail dot com
1 year ago
This is a example of how run a command using as output the TTY, just like crontab -e or git commit does.

<?php

$descriptors
= array(
        array(
'file', '/dev/tty', 'r'),
        array(
'file', '/dev/tty', 'w'),
        array(
'file', '/dev/tty', 'w')
);

$process = proc_open('vim', $descriptors, $pipes);
up
0
bilge at boontex dot com
1 year ago
$cmd can actually be multiple commands by separating each command with a newline. However, due to this it is not possible to split up one very long command over multiple lines, even when using "\\\n" syntax.
up
0
toby at globaloptima dot co dot uk
2 years ago
If script A is spawning script B and script B pushes a lot of data to stdout without script A consuming that data, script B is likely to hang but the result of proc_get_status on that process seems to continue to indicate it's running.

So either don't write to stdout i the spawned process (I write to log files instead now) or try to read in the stdout in a non-blocking way if your script A is spawning many instances of script B, I couldn't get this second option to work sadly.

PHP 5.3.8 CLI on Windows 7 64.
up
0
php at keith tyler dot com
4 years ago
Interestingly enough, it seems you actually have to store the return value in order for your streams to exist. You can't throw it away.

In other words, this works:

<?php
$proc
=proc_open("echo foo",
  array(
    array(
"pipe","r"),
    array(
"pipe","w"),
    array(
"pipe","w")
  ),
 
$pipes);
print
stream_get_contents($pipes[1]);
?>

prints:
foo

but this doesn't work:

<?php
proc_open
("echo foo",
  array(
    array(
"pipe","r"),
    array(
"pipe","w"),
    array(
"pipe","w")
  ),
 
$pipes);
print
stream_get_contents($pipes[1]);
?>

outputs:
Warning: stream_get_contents(): <n> is not a valid stream resource in Command line code on line 1

The only difference is that in the second case we don't save the output of proc_open to a variable.
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0
cbn at grenet dot org
4 years ago
Display output (stdout/stderr) in real time, and get the real exit code in pure PHP (no shell workaround!). It works well on my machines (debian mostly).

#!/usr/bin/php
<?php
/*
* Execute and display the output in real time (stdout + stderr).
*
* Please note this snippet is prepended with an appropriate shebang for the
* CLI. You can re-use only the function.
*
* Usage example:
* chmod u+x proc_open.php
* ./proc_open.php "ping -c 5 google.fr"; echo RetVal=$?
*/
define(BUF_SIZ, 1024);        # max buffer size
define(FD_WRITE, 0);        # stdin
define(FD_READ, 1);        # stdout
define(FD_ERR, 2);        # stderr

/*
* Wrapper for proc_*() functions.
* The first parameter $cmd is the command line to execute.
* Return the exit code of the process.
*/
function proc_exec($cmd)
{
   
$descriptorspec = array(
       
0 => array("pipe", "r"),
       
1 => array("pipe", "w"),
       
2 => array("pipe", "w")
    );

   
$ptr = proc_open($cmd, $descriptorspec, $pipes, NULL, $_ENV);
    if (!
is_resource($ptr))
        return
false;

    while ((
$buffer = fgets($pipes[FD_READ], BUF_SIZ)) != NULL
           
|| ($errbuf = fgets($pipes[FD_ERR], BUF_SIZ)) != NULL) {
        if (!isset(
$flag)) {
           
$pstatus = proc_get_status($ptr);
           
$first_exitcode = $pstatus["exitcode"];
           
$flag = true;
        }
        if (
strlen($buffer))
            echo
$buffer;
        if (
strlen($errbuf))
            echo
"ERR: " . $errbuf;
    }

    foreach (
$pipes as $pipe)
       
fclose($pipe);

   
/* Get the expected *exit* code to return the value */
   
$pstatus = proc_get_status($ptr);
    if (!
strlen($pstatus["exitcode"]) || $pstatus["running"]) {
       
/* we can trust the retval of proc_close() */
       
if ($pstatus["running"])
           
proc_terminate($ptr);
       
$ret = proc_close($ptr);
    } else {
        if (((
$first_exitcode + 256) % 256) == 255
               
&& (($pstatus["exitcode"] + 256) % 256) != 255)
           
$ret = $pstatus["exitcode"];
        elseif (!
strlen($first_exitcode))
           
$ret = $pstatus["exitcode"];
        elseif (((
$first_exitcode + 256) % 256) != 255)
           
$ret = $first_exitcode;
        else
           
$ret = 0; /* we "deduce" an EXIT_SUCCESS ;) */
       
proc_close($ptr);
    }

    return (
$ret + 256) % 256;
}

/* __init__ */
if (isset($argv) && count($argv) > 1 && !empty($argv[1])) {
    if ((
$ret = proc_exec($argv[1])) === false)
        die(
"Error: not enough FD or out of memory.\n");
    elseif (
$ret == 127)
        die(
"Command not found (returned by sh).\n");
    else
        exit(
$ret);
}
?>
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simeonl at dbc dot co dot nz
5 years ago
Note that when you call an external script and retrieve large amounts of data from STDOUT and STDERR, you may need to retrieve from both alternately in non-blocking mode (with appropriate pauses if no data is retrieved), so that your PHP script doesn't lock up. This can happen if you waiting on activity on one pipe while the external script is waiting for you to empty the other, e.g:

<?php
$read_output
= $read_error = false;
$buffer_len  = $prev_buffer_len = 0;
$ms          = 10;
$output      = '';
$read_output = true;
$error       = '';
$read_error  = true;
stream_set_blocking($pipes[1], 0);
stream_set_blocking($pipes[2], 0);

// dual reading of STDOUT and STDERR stops one full pipe blocking the other, because the external script is waiting
while ($read_error != false or $read_output != false)
{
    if (
$read_output != false)
    {
        if(
feof($pipes[1]))
        {
           
fclose($pipes[1]);
           
$read_output = false;
        }
        else
        {
           
$str = fgets($pipes[1], 1024);
           
$len = strlen($str);
            if (
$len)
            {
               
$output .= $str;
               
$buffer_len += $len;
            }
        }
    }
   
    if (
$read_error != false)
    {
        if(
feof($pipes[2]))
        {
           
fclose($pipes[2]);
           
$read_error = false;
        }
        else
        {
           
$str = fgets($pipes[2], 1024);
           
$len = strlen($str);
            if (
$len)
            {
               
$error .= $str;
               
$buffer_len += $len;
            }
        }
    }
   
    if (
$buffer_len > $prev_buffer_len)
    {
       
$prev_buffer_len = $buffer_len;
       
$ms = 10;
    }
    else
    {
       
usleep($ms * 1000); // sleep for $ms milliseconds
       
if ($ms < 160)
        {
           
$ms = $ms * 2;
        }
    }
}
       
return
proc_close($process);
?>
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snowleopard at amused dot NOSPAMPLEASE dot com dot au
6 years ago
I managed to make a set of functions to work with GPG, since my hosting provider refused to use GPG-ME.
Included below is an example of decryption using a higher descriptor to push a passphrase.
Comments and emails welcome. :)

<?php
function GPGDecrypt($InputData, $Identity, $PassPhrase, $HomeDir="~/.gnupg", $GPGPath="/usr/bin/gpg") {
   
    if(!
is_executable($GPGPath)) {
       
trigger_error($GPGPath . " is not executable",
       
E_USER_ERROR);
        die();
    } else {
       
// Set up the descriptors
       
$Descriptors = array(
           
0 => array("pipe", "r"),
           
1 => array("pipe", "w"),
           
2 => array("pipe", "w"),
           
3 => array("pipe", "r") // This is the pipe we can feed the password into
       
);

       
// Build the command line and start the process
       
$CommandLine = $GPGPath . ' --homedir ' . $HomeDir . ' --quiet --batch --local-user "' . $Identity . '" --passphrase-fd 3 --decrypt -';
       
$ProcessHandle = proc_open( $CommandLine, $Descriptors, $Pipes);

        if(
is_resource($ProcessHandle)) {
           
// Push passphrase to custom pipe
           
fwrite($Pipes[3], $PassPhrase);
           
fclose($Pipes[3]);
           
           
// Push input into StdIn
           
fwrite($Pipes[0], $InputData);
           
fclose($Pipes[0]);
           
           
// Read StdOut
           
$StdOut = '';
            while(!
feof($Pipes[1])) {
               
$StdOut .= fgets($Pipes[1], 1024);
            }
           
fclose($Pipes[1]);
           
           
// Read StdErr
           
$StdErr = '';
            while(!
feof($Pipes[2]))    {
               
$StdErr .= fgets($Pipes[2], 1024);
            }
           
fclose($Pipes[2]);

           
// Close the process
           
$ReturnCode = proc_close($ProcessHandle);

        } else {
           
trigger_error("cannot create resource", E_USER_ERROR);
            die();
        }
    }
   
    if (
strlen($StdOut) >= 1) {
        if (
$ReturnCode <= 0) {
           
$ReturnValue = $StdOut;
        } else {
           
$ReturnValue = "Return Code: " . $ReturnCode . "\nOutput on StdErr:\n" . $StdErr . "\n\nStandard Output Follows:\n\n";
        }
    } else {
        if (
$ReturnCode <= 0) {
           
$ReturnValue = $StdErr;
        } else {
           
$ReturnValue = "Return Code: " . $ReturnCode . "\nOutput on StdErr:\n" . $StdErr;
        }
    }
    return
$ReturnValue;
}
?>
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jonah at whalehosting dot ca
6 years ago
@joachimb: The descriptorspec describes the i/o from the perspective of the process you are opening.  That is why stdin is read: you are writing, the process is reading.  So you want to open descriptor 2 (stderr) in write mode so that the process can write to it and you can read it.  In your case where you want all descriptors to be pipes you should always use:

<?php
$descriptorspec
= array(
   
0 => array('pipe', 'r'), // stdin
   
1 => array('pipe', 'w'), // stdout
   
2 => array('pipe', 'w') // stderr
);
?>

The examples below where stderr is opened as 'r' is a mistake.

I would like to see examples of using higher descriptor numbers than 2.  Specifically GPG as mentioned in the documentation.
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joachimb at gmail dot com
6 years ago
I'm confused by the direction of the pipes. Most of the examples in this documentation opens pipe #2 as "r", because they want to read from stderr. That sounds logical to me, and that's what I tried to do. That didn't work, though. When I changed it to w, as in
<?php
        $descriptorspec
= array(
          
0 => array("pipe", "r"), // stdin
          
1 => array("pipe", "w"), // stdout
          
2 => array("pipe", "w") // stderr
       
);
       
       
$process = proc_open(escapeshellarg($scriptFile), $descriptorspec, $pipes, $this->wd);
...
        while (!
feof($pipes[1])) {
            foreach(
$pipes as $key =>$pipe) {
               
$line = fread($pipe, 128);
                if(
$line) {
                    print(
$line);
                   
$this->log($line);
                }
            }
           
sleep(0.5);
        }
...
?>

everything works fine.
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jaroslaw at pobox dot sk
6 years ago
Some functions stops working proc_open() to me.
This i made to work for me to communicate between two php scripts:

<?php
$abs_path
= '/var/www/domain/filename.php';
$spec = array(array("pipe", "r"), array("pipe", "w"), array("pipe", "w"));
$process = proc_open('php '.$abs_path, $spec, $pipes, null, $_ENV);
if (
is_resource($process)) {
   
# wait till something happens on other side
   
sleep(1);
   
# send command
   
fwrite($pipes[0], 'echo $test;');
   
fflush($pipes[0]);
   
# wait till something happens on other side
   
usleep(1000);
   
# read pipe for result
   
echo fread($pipes[1],1024).'<hr>';
   
# close pipes
   
fclose($pipes[0]);fclose($pipes[1]);fclose($pipes[2]);
   
$return_value = proc_close($process);
}
?>

filename.php then contains this:

<?php
$test
= 'test data generated here<br>';
while(
true) {
   
# read incoming command
   
if($fh = fopen('php://stdin','rb')) {
       
$val_in = fread($fh,1024);
       
fclose($fh);
    }
   
# execute incoming command
   
if($val_in)
        eval(
$val_in);
   
usleep(1000);
   
# prevent neverending cycle
   
if($tmp_counter++ > 100)
        break;
}
?>
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0
Antti Kauppinen
7 years ago
missilesilo at gmail dot com had a great example. However error messages didn't work because of wrong stderr argument.

I changed last value 'r' of

<?php
        $descriptorspec
= array(
           
0 => array('pipe', 'r'),
           
1 => array('pipe', 'w'),
           
2 => array('pipe', 'r')
        );
?>

to 'w' so that error messages are actually written.

<?php
        $descriptorspec
= array(
           
0 => array("pipe", "r"),  // stdin is a pipe that the child will read from
           
1 => array("pipe", "w"),  // stdout is a pipe that the child will write to
           
2 => array("pipe", "w") // stderr is a file to write to
       
);
?>
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mjutras at beenox dot com
7 years ago
The best way on windows to open a process then to let the php script continue is to call your process with the start command then to kill the "start" process and let your program run.

<?
$descriptorspec = array(
       0 => array("pipe", "r"),   // stdin
       1 => array("pipe", "w"),  // stdout
       2 => array("pipe", "w")   // stderr
);
$process = proc_open('start notepad.exe', $descriptorspec, $pipes);
sleep(1);
proc_close($process);
?>

The start command will be called then open notepad, after 1 second the "start" command will be killed but the notepad will still opened and your php script can continue!
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Docey
8 years ago
if your writing a function that processes a resource from
another function its a good idea not only to check whether
a resource has been passed to your function but also if its
of the good type like so:

<?php
function workingonit($resource){
if(
is_resource($resource)){
   if(
get_resource_type($resource) == "resource_type"){
   
// resource is a resource and of the good type. continue
  
}else{
    print(
"resource is of the wrong type.");
    return
false;
   }
}else{
  print(
"resource passed is not a resource at all.");
  return
false;
}

// do your stuff with the resource here and return
}
?>

this is extra true for working with files and process pipes.
so always check whats being passed to your functions.

here's a small snipppet of a few resource types:
files are of type 'file' in php4 and 'stream' in php5
'prossess' are resources opened by proc_open.
'pipe' are resource opened by popen.

btw the 'prossess' resource type was not mentioned in
the documentation. i make a bug-report for this.
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richard at 2006 dot atterer dot net
8 years ago
[Again, please delete my previous comment, the code still contained bugs (sorry). This version now includes Frederick Leitner&#039;s fix from below, and also fixes another bug: If an empty file was piped into the process, the loop would hang indefinitely.]

The following code works for piping large amounts of data through a filtering program. I find it very weird that such a lot of code is needed for this task... On entry, $stdin contains the standard input for the program. Tested on Debian Linux with PHP 5.1.2.

&lt;?php
  $descriptorSpec = array(0 =&gt; array(&quot;pipe&quot;, &quot;r&quot;),
                           1 =&gt; array(&#039;pipe&#039;, &#039;w&#039;),
                           2 =&gt; array(&#039;pipe&#039;, &#039;w&#039;));
  $process = proc_open($command, $descriptorSpec, $pipes);
  $txOff = 0; $txLen = strlen($stdin);
  $stdout = &#039;&#039;; $stdoutDone = FALSE;
  $stderr = &#039;&#039;; $stderrDone = FALSE;
  stream_set_blocking($pipes[0], 0); // Make stdin/stdout/stderr non-blocking
  stream_set_blocking($pipes[1], 0);
  stream_set_blocking($pipes[2], 0);
  if ($txLen == 0) fclose($pipes[0]);
  while (TRUE) {
    $rx = array(); // The program&#039;s stdout/stderr
    if (!$stdoutDone) $rx[] = $pipes[1];
    if (!$stderrDone) $rx[] = $pipes[2];
    $tx = array(); // The program&#039;s stdin
    if ($txOff &lt; $txLen) $tx[] = $pipes[0];
    stream_select($rx, $tx, $ex = NULL, NULL, NULL); // Block til r/w possible
    if (!empty($tx)) {
      $txRet = fwrite($pipes[0], substr($stdin, $txOff, 8192));
      if ($txRet !== FALSE) $txOff += $txRet;
      if ($txOff &gt;= $txLen) fclose($pipes[0]);
    }
    foreach ($rx as $r) {
      if ($r == $pipes[1]) {
        $stdout .= fread($pipes[1], 8192);
        if (feof($pipes[1])) { fclose($pipes[1]); $stdoutDone = TRUE; }
      } else if ($r == $pipes[2]) {
        $stderr .= fread($pipes[2], 8192);
        if (feof($pipes[2])) { fclose($pipes[2]); $stderrDone = TRUE; }
      }
    }
    if (!is_resource($process)) break;
    if ($txOff &gt;= $txLen &amp;&amp; $stdoutDone &amp;&amp; $stderrDone) break;
  }
  $returnValue = proc_close($process);
?&gt;
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Kevin Barr
8 years ago
I found that with disabling stream blocking I was sometimes attempting to read a return line before the external application had responded. So, instead, I left blocking alone and used this simple function to add a timeout to the fgets function:

// fgetsPending( $in,$tv_sec ) - Get a pending line of data from stream $in, waiting a maximum of $tv_sec seconds
function fgetsPending(&$in,$tv_sec=10) {
    if ( stream_select($read = array($in),$write=NULL,$except=NULL,$tv_sec) ) return fgets($in);
    else return FALSE;   
}
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andrew dot budd at adsciengineering dot com
8 years ago
The pty option is actually disabled in the source for some reason via a #if 0 && condition.  I'm not sure why it's disabled.  I removed the 0 && and recompiled, after which the pty option works perfectly.  Just a note.
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mendoza at pvv dot ntnu dot no
8 years ago
Since I don't have access to PAM via Apache, suexec on, nor access to /etc/shadow I coughed up this way of authenticating users based on the system users details. It's really hairy and ugly, but it works.

<?
function authenticate($user,$password) {
  $descriptorspec = array(
     0 => array("pipe", "r"),  // stdin is a pipe that the child will read from
     1 => array("pipe", "w"),  // stdout is a pipe that the child will write to
     2 => array("file","/dev/null", "w") // stderr is a file to write to
  );

  $process = proc_open("su ".escapeshellarg($user), $descriptorspec, $pipes);

  if (is_resource($process)) {
    // $pipes now looks like this:
    // 0 => writeable handle connected to child stdin
    // 1 => readable handle connected to child stdout
    // Any error output will be appended to /tmp/error-output.txt

    fwrite($pipes[0],$password);
    fclose($pipes[0]);
    fclose($pipes[1]);

    // It is important that you close any pipes before calling
    // proc_close in order to avoid a deadlock
    $return_value = proc_close($process);

    return !$return_value;
  }
}
?>
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picaune at hotmail dot com
8 years ago
The above note on Windows compatibility is not entirely correct.

Windows will dutifully pass on additional handles above 2 onto the child process, starting with Windows 95 and Windows NT 3.5. It even supports this capability (starting with Windows 2000) from the command line using a special syntax (prefacing the redirection operator with the handle number).

These handles will be, when passed to the child, preopened for low-level IO (e.g. _read) by number. The child can reopen them for high-level (e.g. fgets) using the _fdopen or _wfdopen methods. The child can then read from or write to them the same way they would stdin or stdout.

However, child processes must be specially coded to use these handles, and if the end user is not intelligent enough to use them (e.g. "openssl < commands.txt 3< cacert.der") and the program not smart enough to check, it could cause errors or hangs.
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0
Chapman Flack
8 years ago
One can learn from the source code in ext/standard/exec.c that the right-hand side of a descriptor assignment does not have to be an array ('file', 'pipe', or 'pty') - it can also be an existing open stream.

<?php
$p
= proc_open('myfilter', array( 0 => $infile, ...), $pipes);
?>

I was glad to learn that because it solves the race condition in a scenario like this: you get a file name, open the file, read a little to make sure it's OK to serve to this client, then rewind the file and pass it as input to the filter. Without this feature, you would be limited to <?php array('file', $fname) ?> or passing the name to the filter command. Those choices both involve a race (because the file will be reopened after you have checked it's OK), and the last one invites surprises if not carefully quoted, too.
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0
falstaff at arragon dot biz
9 years ago
Using this function under windows with large amounts of data is apparently futile.

these functions are returning 0 but do not appear to be doing anything useful.
stream_set_write_buffer($pipes[0],0);
stream_set_write_buffer($pipes[1],0);

these functions are returning false and are also apparently useless under windows.
stream_set_blocking($pipes[0], FALSE);
stream_set_blocking($pipes[1], FALSE);

The magic max buffer size I found with winxp is 63488 bytes, (62k). Anything larger than this results in a system hang.
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0
Andre Caldas
10 years ago
About the comment by  ch at westend dot com
of 28-Aug-2003 08:46

File streams are buffers. The data is not actualy written if you do not flush the buffer. In your case, fclose has the side effect of flushing the buffer you are closing.

The program "hangs" because it tries to read some data that was not written (since it is buffered).

You must do something like:
<?php
  fwrite
($fp);
 
fflush($fp);
 
fread($fp);
?>

Good luck,
    Andre Caldas.
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ralf at dreesen[*NO*SPAM*] dot net
10 years ago
The behaviour described in the following may depend on the system php runs on. Our platform was "Intel with Debian 3.0 linux".

If you pass huge amounts of data (ca. >>10k) to the application you run and the application for example echos them directly to stdout (without buffering the input), you will get a deadlock. This is because there are size-limited buffers (so called pipes) between php and the application you run. The application will put data into the stdout buffer until it is filled, then it blocks waiting for php to read from the stdout buffer. In the meantime Php filled the stdin buffer and waits for the application to read from it. That is the deadlock.

A solution to this problem may be to set the stdout stream to non blocking (stream_set_blocking) and alternately write to stdin and read from stdout.

Just imagine the following example:

<?
/* assume that strlen($in) is about 30k
*/

$descriptorspec = array(
   0 => array("pipe", "r"),
   1 => array("pipe", "w"),
   2 => array("file", "/tmp/error-output.txt", "a")
);

$process = proc_open("cat", $descriptorspec, $pipes);

if (is_resource($process)) {

   fwrite($pipes[0], $in);
    /* fwrite writes to stdin, 'cat' will immediately write the data from stdin
    * to stdout and blocks, when the stdout buffer is full. Then it will not
    * continue reading from stdin and php will block here.
    */

   fclose($pipes[0]);

   while (!feof($pipes[1])) {
       $out .= fgets($pipes[1], 1024);
   }
   fclose($pipes[1]);

   $return_value = proc_close($process);
}
?>
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MagicalTux at FF.ST
10 years ago
Note that if you need to be "interactive" with the user *and* the opened application, you can use stream_select to see if something is waiting on the other side of the pipe.

Stream functions can be used on pipes like :
- pipes from popen, proc_open
- pipes from fopen('php://stdin') (or stdout)
- sockets (unix or tcp/udp)
- many other things probably but the most important is here

More informations about streams (you'll find many useful functions there) :
http://www.php.net/manual/en/ref.stream.php
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ch at westend dot com
10 years ago
I had trouble with this function as my script always hung like in a deadlock until I figured out that I had to strictly keep the following
order. Trying to close all at the end did not work!
  proc_open();
  fwrite(pipes[0]); fclose(pipes[0]); # stdin
  fread(pipes[1]);  fclose(pipes[1]); # stdout
  fread(pipes[2]);  flcose(pipes[2]); # stderr
  proc_close();
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-1
list[at]public[dot]lt
10 years ago
if you push a little bit more data through the pipe, it will be hanging forever. One simple solution  on RH linux was to do this:

stream_set_blocking($pipes[0], FALSE);
stream_set_blocking($pipes[1], FALSE);

This did not work on windows XP though.
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-2
Matou Havlena - matous at havlena dot net
4 years ago
There is some smart object Processes Manager which i have created for my application. It can control the maximum of simultaneously running processes.

Proccesmanager class:
<?php
class Processmanager {
    public
$executable = "C:\\www\\_PHP5_2_10\\php";
    public
$root = "C:\\www\\parallelprocesses\\";
    public
$scripts = array();
    public
$processesRunning = 0;
    public
$processes = 3;
    public
$running = array();
    public
$sleep_time = 2;
   
    function
addScript($script, $max_execution_time = 300) {
       
$this->scripts[] = array("script_name" => $script,
                           
"max_execution_time" => $max_execution_time);
    }
   
    function
exec() {
       
$i = 0;
        for(;;) {
       
// Fill up the slots
       
while (($this->processesRunning<$this->processes) and ($i<count($this->scripts))) {
        echo
"<span style='color: orange;'>Adding script: ".$this->scripts[$i]["script_name"]."</span><br />";
       
ob_flush();
       
flush();
       
$this->running[] =& new Process($this->executable, $this->root, $this->scripts[$i]["script_name"], $this->scripts[$i]["max_execution_time"]);
       
$this->processesRunning++;
       
$i++;
        }
       
       
// Check if done
       
if (($this->processesRunning==0) and ($i>=count($this->scripts))) {
            break;
        }
       
// sleep, this duration depends on your script execution time, the longer execution time, the longer sleep time
     
sleep($this->sleep_time);
     
     
// check what is done
       
foreach ($this->running as $key => $val) {
                if (!
$val->isRunning() or $val->isOverExecuted()) {
            if (!
$val->isRunning()) echo "<span style='color: green;'>Done: ".$val->script."</span><br />";
            else echo
"<span style='color: red;'>Killed: ".$val->script."</span><br />";
                   
proc_close($val->resource);
                    unset(
$this->running[$key]);
                   
$this->processesRunning--;
           
ob_flush();
           
flush();
                }
            }
        }
    }
}
?>

Process class:
<?php
class Process {
    public
$resource;
    public
$pipes;
    public
$script;
    public
$max_execution_time;
    public
$start_time;
   
    function
__construct(&$executable, &$root, $script, $max_execution_time) {
       
$this->script = $script;
       
$this->max_execution_time = $max_execution_time;
       
$descriptorspec    = array(
           
0 => array('pipe', 'r'),
           
1 => array('pipe', 'w'),
           
2 => array('pipe', 'w')
        );
       
$this->resource    = proc_open($executable." ".$root.$this->script, $descriptorspec, $this->pipes, null, $_ENV);
       
$this->start_time = mktime();
    }
   
   
// is still running?
   
function isRunning() {
       
$status = proc_get_status($this->resource);
        return
$status["running"];
    }

   
// long execution time, proccess is going to be killer
   
function isOverExecuted() {
        if (
$this->start_time+$this->max_execution_time<mktime()) return true;
        else return
false;
    }

}
?>

Example of using:
<?php
$manager
= new Processmanager();
$manager->executable = "C:\\www\\_PHP5_2_10\\php";
$manager->path = "C:\\www\\parallelprocesses\\";
$manager->processes = 3;
$manager->sleep_time = 2;
$manager->addScript("script1.php", 10);
$manager->addScript("script2.php");
$manager->addScript("script3.php");
$manager->addScript("script4.php");
$manager->addScript("script5.php");
$manager->addScript("script6.php");
$manager->exec();
?>

And possible output:

Adding script: script1.php
Adding script: script2.php
Adding script: script3.php
Done: script2.php
Adding script: script4.php
Killed: script1.php
Done: script3.php
Done: script4.php
Adding script: script5.php
Adding script: script6.php
Done: script5.php
Done: script6.php
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