proc_open

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

proc_open — 执行一个命令，并且打开用来输入/输出的文件指针。

说明

proc_open ( mixed $cmd , array $descriptorspec , array &$pipes , string $cwd = null , array $env = null , array $other_options = null ) : resource

类似 popen() 函数， 但是 proc_open() 提供了更加强大的控制程序执行的能力。

参数

cmd

以 string 形式执行的命令行。特殊字符必须经过转义，并且使用正确的引号。

Note: 在 Windows 上, 除非在 other_options 中 把 bypass_shell 设置为 true ，否则 cmd 会被传递给 cmd.exe （实际上是 %ComSpec%） 其中的 /c 标志是 未加引号的 字符串 （也就是和 proc_open() 一样）。 这可能会导致 cmd.exe 删除 cmd 中的引号 （详见 cmd.exe 文档）， 从而导致意外的，甚至是潜在的危险行为，因为 cmd.exe 错误消息可能包含 （部分） 传递的 cmd （见下面的例子）。

从 PHP 7.4.0 开始，cmd 参数可以使用 array 类型传递。 在这种情况下，进程将直接打开（不通过 shell ）。 而 PHP 会处理任何必要的参数转义。

Note:

在 Windows 上， array 元素的参数转义假定 执行命令的命令行解析与 VC 运行时进行的命令行参数解析兼容。

descriptorspec

一个索引数组。 数组的键表示描述符，数组元素值表示 PHP 如何将这些描述符传送至子进程。 0 表示标准输入（stdin），1 表示标准输出（stdout），2 表示标准错误（stderr）。

数组中的元素可以是：

  • 包含了要传送至进程的管道的描述信息的数组。 第一个元素为描述符类型， 第二个元素是针对该描述符的选项。 有效的类型有：pipe （第二个元素可以是： r 向进程传送该管道的读取端，w 向进程传送该管道的写入端）， 以及 file（第二个元素为文件名）。
  • 表达一个真实文件描述符的流资源类型 （例如：已打开的文件，一个 socket 端口，STDIN）。

文件描述符的值不限于 0，1 和 2，你可以使用任何有效的文件描述符 并将其传送至子进程。 这使得你的脚本可以和其他脚本交互操作。 例如，可以通过指定文件描述符将密码以更加安全的方式 传送至诸如 PGP，GPG 和 openssl 程序， 同时也可以很方便的获取这些程序的状态信息。

pipes

将被置为索引数组， 其中的元素是被执行程序创建的管道对应到 PHP 这一端的文件指针。

cwd

要执行命令的初始工作目录。 必须是 绝对 路径， 设置此参数为 null 表示使用默认值（当前 PHP 进程的工作目录）。

env

要执行的命令所使用的环境变量。 设置此参数为 null 表示使用和当前 PHP 进程相同的环境变量。

other_options

你还可以指定一些附加选项。 目前支持的选项包括：

  • suppress_errors （仅用于 Windows 平台）： 设置为 true 表示抑制本函数产生的错误。
  • bypass_shell （仅用于 Windows 平台）： 设置为 true 表示绕过 cmd.exe shell。
  • blocking_pipes （仅用于 Windows 平台）： 设置为 true 表示强制堵塞管道。
  • create_process_group （仅用于 Windows 平台）： 设置为 true 表示允许子进程处理 CTRL 事件。
  • create_new_console （仅用于 Windows 平台）： 表示新进程有一个新的控制台，用于代替父进程的控制台。

返回值

返回表示进程的资源类型， 当使用完毕之后，请调用 proc_close() 函数来关闭此资源。 如果失败，返回 false。

更新日志

版本 说明
7.4.4 为 other_options 参数增加 create_new_console 选项。
7.4.0 proc_open() 的 cmd 参数现在也允许数组类型。
7.4.0 为 other_options 参数增加 create_process_group 选项。

范例

Example #1 proc_open() 例程

<?php
$descriptorspec = array(
   0 => array("pipe", "r"),  // 标准输入，子进程从此管道中读取数据
   1 => array("pipe", "w"),  // 标准输出，子进程向此管道中写入数据
   2 => array("file", "/tmp/error-output.txt", "a") // 标准错误，写入到一个文件
);

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

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

if (is_resource($process)) {
    // $pipes 现在看起来是这样的：
    // 0 => 可以向子进程标准输入写入的句柄
    // 1 => 可以从子进程标准输出读取的句柄
    // 错误输出将被追加到文件 /tmp/error-output.txt

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

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

    // 切记：在调用 proc_close 之前关闭所有的管道以避免死锁。
    $return_value = proc_close($process);

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

以上例程的输出类似于：

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

Example #2 proc_open() 在 Windows 上的怪异行为

虽然人们可能期望下面的程序能够搜索文件 filename.txt 进行文本搜索， 并打印结果，但它的行为相当不同。

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

以上例程会输出：

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

要解决该行为，通常只需将 cmd 加上引号：

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

注释

Note:

Windows 兼容性：超过 2 的描述符也可以作为可继承的句柄传送到子进程。 但是，由于 Windows 的架构并不将文件描述符和底层句柄进行关联， 所以，子进程无法访问这样的句柄。 标准输入，标准输出和标注错误会按照预期工作。

Note:

如果你只需要单向的进程管道， 使用 popen() 函数会更加简单。

参见

  • popen() - 打开进程文件指针
  • exec() - 执行一个外部程序
  • system() - 执行外部程序，并且显示输出
  • passthru() - 执行外部程序并且显示原始输出
  • stream_select() - Runs the equivalent of the select() system call on the given arrays of streams with a timeout specified by tv_sec and tv_usec
  • The 执行运算符

User Contributed Notes

weirdall at hotmail dot com 07-Feb-2017 03:01
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);
}
?>
stoller at leonex dot de 08-Apr-2016 07:37
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));
}
?>
aaronw at catalyst dot net dot nz 05-Oct-2015 11:16
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);
?>
stevebaldwin21 at googlemail dot com 31-Aug-2015 06:32
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)
);
vanyazin at gmail dot com 25-Jun-2015 04:47
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);
hablutzel1 at gmail dot com 15-Apr-2015 05:26
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.
exel at example dot com 26-Sep-2013 10:05
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";
?>
mcuadros at gmail dot com 05-Apr-2013 10:56
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);
michael dot gross at NOSPAM dot flexlogic dot at 03-Jan-2013 08:33
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).
bilge at boontex dot com 05-Sep-2012 02:56
$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.
devel at romanr dot info 10-Mar-2012 08:04
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.
toby at globaloptima dot co dot uk 14-Nov-2011 01:38
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.
mattis at xait dot no 03-Feb-2011 07:41
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
php at keith tyler dot com 16-Apr-2010 11:32
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.
Matou Havlena - matous at havlena dot net 14-Apr-2010 01:03
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
Luceo 28-Mar-2010 07:39
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
);
?>
cbn at grenet dot org 18-Dec-2009 07:30
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);
}
?>
simeonl at dbc dot co dot nz 03-Mar-2009 06:39
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);
?>
snowleopard at amused dot NOSPAMPLEASE dot com dot au 05-Jun-2008 07:46
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;
}
?>
radone at gmail dot com 26-May-2008 05:26
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;
    }
}
?>
jonah at whalehosting dot ca 02-May-2008 10:22
@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.
joachimb at gmail dot com 30-Apr-2008 08:24
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.
jaroslaw at pobox dot sk 28-Mar-2008 02:15
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;
}
?>
chris AT w3style DOT co.uk 22-Feb-2008 02:57
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.
Anonymous 27-Dec-2007 07:40
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
John Wehin 06-Dec-2007 10:52
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);}
}
?>
php dot net_manual at reimwerker dot de 03-Jun-2006 04:47
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.
Kevin Barr 06-Mar-2006 12:36
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;   
}
andrew dot budd at adsciengineering dot com 28-Dec-2005 09:55
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.
mendoza at pvv dot ntnu dot no 21-Oct-2005 10:42
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;
  }
}
?>
picaune at hotmail dot com 16-Oct-2005 04:51
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.
Kyle Gibson 05-Aug-2005 12:16
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.
ralf at dreesen[*NO*SPAM*] dot net 09-Jan-2004 11:49
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);
}
?>
MagicalTux at FF.ST 24-Dec-2003 04:20
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
daniela at itconnect dot net dot au 16-Apr-2003 02:01
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);
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