popen

(PHP 4, PHP 5, PHP 7, PHP 8)

popenCrée un processus de pointeur de fichier

Description

popen(string $command, string $mode): resource|false

Crée un processus de pointeur de fichier, exécuté en effectuant un fork de la commande fournie par le paramètre command.

Liste de paramètres

command

La commande

mode

Le mode. Soit 'r' pour lecture, soit 'w' pour l'écriture.

Sur Windows, popen() utilise le mode texte par défaut, c.à.d. tout caractères \n écrit ou lu du pipe sera traduit en \r\n. Si ceci n'est pas désiré, le mode binaire peut être enforcé en définissant le mode à 'rb' et 'wb', respectivement.

Valeurs de retour

Retourne un pointeur de fichier identique à celui retourné par fopen(), hormis le fait qu'il sera unidirectionnel (lecture seule, ou écriture seule), et doit être terminé par pclose(). Ce pointeur peut être utilisé avec fgets(), fgetss() et fwrite(). Lorsque le mode est 'r', le pointeur de fichier retourné équivaut au STDOUT de la commande, et lorsque le mode est 'w', le pointeur de fichier retourné équivaut au STDIN de la commande.

Si une erreur survient, la fonction retournera false.

Exemples

Exemple #1 Exemple avec popen()

<?php
$handle
= popen("/bin/ls", "r");
?>

Si la commande à exécuter n'a pu être trouvée, une ressource valide sera retournée. Cela semble étrange, mais c'est pratique. cela vous permet d'accéder aux messages d'erreur qui ont été retournés par le Shell :

Exemple #2 Exemple avec popen()

<?php
error_reporting
(E_ALL);

/* Ajoute une redirection pour que vous puissiez lire stderr. */
$handle = popen('/path/to/executable 2>&1', 'r');
echo
"'$handle'; " . gettype($handle) . "\n";
$read = fread($handle, 2096);
echo
$read;
pclose($handle);
?>

Notes

Note:

Si vous souhaitez un support bidirectionnel (two-way), utilisez la fonction proc_open().

Voir aussi

  • pclose() - Ferme un processus de pointeur de fichier
  • fopen() - Ouvre un fichier ou une URL
  • proc_open() - Exécute une commande et ouvre les pointeurs de fichiers pour les entrées / sorties

add a note add a note

User Contributed Notes 23 notes

up
19
webmaster at php-idee dot de
14 years ago
If you try to execute a command under Windows the PHP script normally waits until the process has been terminated. Executing long-term processes pauses a PHP script even if you don't want to wait for the end of the process.

It wasn't easy to find this beautiful example how to start a process under Windows without waiting for its termination:

<?php
$commandString
= 'start /b c:\\programToRun.exe -attachment "c:\\temp\file1.txt"';
pclose(popen($commandString, 'r'));
?>
up
11
anonymous at anon dot com
13 years ago
If, on windows, you need to start a batch file that needs administrator privileges, then you can make a shortcut to the batch file, click properties, check to on "run as administrator" on one of the property pages, and then double-click the shortcut once (to initialize that "run as administrator" business).

using popen("/path/to/shortcut.lnk") will then run your batch file with administrator privileges.

handy for when you want to use cli php to do some long running tasks and that php-cli needs to use sessions..
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8
anonymous at anon dot com
8 years ago
As a side note to the code provided by anonymous at anon dot com:

  $cmd = "php longscript.php";

  function execInBackground($cmd) { 
    if (substr(php_uname(), 0, 7) == "Windows"){
        pclose(popen("start /B ". $cmd, "r"));
    } else {
        exec($cmd . " > /dev/null &");  
    }
  }

I had a problem where Windows would close the call too fast before the entire script was interpreted, but I didn't want my main script to hang until it would be fully loaded.

As a workaround, I called a tiny .php script which would then call the larger script.

myfile.php:
<?php
  $cmd
= "php timewrapper.php";

  function
execInBackground($cmd) { 
    if (
substr(php_uname(), 0, 7) == "Windows"){
       
pclose(popen("start /B ". $cmd, "r"));
    } else {
       
exec($cmd . " > /dev/null &");  
    }
  }
?>

timewrapper.php:
<?php
  $cmd
= "php longscript.php";
 
$timer = popen("start /B ". $cmd, "r");
 
sleep(30);
 
pclose($timer);
?>

This way my main script would continue to run without having to pause, while the tiny script pauses while it loads the larger file.
up
7
rockytriton
16 years ago
Note, when using this with a batch file in windows, you must put an "exit" at the end of your batch file or you will get a new cmd.exe stuck in your process list every time you execute the page.
up
4
jlh
7 years ago
Don't expect this function to return false when the executable doesn't exist in the first place. A stream will be opened anyway but nothing can be read from it. An error similar to "sh: 1: asdfasdfasdf: not found" will be printed to STDERR.

Solution 1: Look at the return value of pclose(), it will be the exit status of the shell that runs the command. On Linux it will be 127 if the executable wasn't found. Otherwise it's the exit status of the executable itself.

Solution 2: Use proc_open() instead, which allows to also capture STDERR and then parse it for errors.

You probably should do both.
up
3
rjl at xs4all dot nl
18 years ago
Truncated output from ps command?

The solution lies in the way ps displays it's info
specifically the -w option which:
'uses 132 columns to display information,
instead of the default which is your window size.'....
somehow with fgets in php that results in 74 characters
regardless off the init length parameter

a bit of code:

<?php
echo '<table width="99%"><tr><td>cron</td></tr>' . "\n";
$fp=popen("/bin/ps -waux","r");
while (!
feof($fp)) {
   
$buffer = fgets($fp, 4096);
   
$croninf .= '<tr><td>' . $buffer . '</td></tr>' . "\n";
}
pclose($fp);
echo
$croninf;
echo
'</table><br><br>' . "\n";
?>

Ciao,

Rene =<>=
up
2
don at digithink dot com
18 years ago
<?php
// The above import function can be easily extended using
// /usr/local/bin/xls2csv (part of catdoc ) and popen
// to read excell files directly.
// In our particular application the first line was the file heading.
function importxls($file,$head=true,$throwfirst=true,$delim=",",$len=1000) {
  
$return = false;
  
$handle = popen("/usr/local/bin/xls2csv $file", "r");
// or die if not there.
  
if ($throwfirst) {
      
$throw = fgetcsv($handle, $len, $delim);
   }
   if (
$head) {
      
$header = fgetcsv($handle, $len, $delim);
   }
   while ((
$data = fgetcsv($handle, $len, $delim)) !== FALSE) {
       if (
$head AND isset($header)) {
           foreach (
$header as $key=>$heading) {
              
$row[$heading]=(isset($data[$key])) ? $data[$key] : '';
               print
"<li>". $heading ."=>" . $row[$heading]."</li>";
           }
          
$return[]=$row;
       } else {
          
$return[]=$data;
       }
   }
  
fclose($handle);
   return
$return;
}
?>
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3
Marbug at gmail dot com
15 years ago
If you want to download files from a linux server with a filesize bigger than 2GB you can use the following:

<?php
function serveFile( $file , $as ){
   
header( 'Expires: Mon, 1 Apr 1974 05:00:00 GMT' );
   
header( 'Pragma: no-cache' );
   
header( 'Cache-Control: must-revalidate, post-check=0, pre-check=0' );
   
header( 'Content-Description: File Download' );
   
header( 'Content-Type: application/octet-stream' );
   
header( 'Content-Length: '.trim(`stat -c%s "$file"`) );
   
header( 'Content-Disposition: attachment; filename="'. $as .'"' );
   
header( 'Content-Transfer-Encoding: binary' );
   
//@readfile( $file );

   
flush();
   
$fp = popen("tail -c ".trim(`stat -c%s "$file"`)." ".$file.' 2>&1', "r");
    while(!
feof($fp))
    {
       
// send the current file part to the browser
       
print fread($fp, 1024);
       
// flush the content to the browser
       
flush();
    }
   
fclose($fp);
}
?>
up
2
hacklor [AT] NOSPAM [DOT] com
13 years ago
There is a simple way to start a process in the background but still find out what the process result is. I combined the information from some users below with some of my own coming up with the following:

<?php
$bat_filename
= "C:\\my_bat_file.bat";
$bat_log_filename = "C:\\my_bat_file_bat.log";
$bat_file = fopen($bat_filename, "w");
if(
$bat_file) {
   
fwrite($bat_file, "@echo off"."\n");
   
fwrite($bat_file, "echo Starting proces >> ".$bat_log_filename."\n");
   
fwrite($bat_file, "php c:\\my_php_process.php >> ".$bat_log_filename."\n");
   
fwrite($bat_file, "echo End proces >> ".$bat_log_filename."\n");
   
fwrite($bat_file, "EXIT"."\n");
   
fclose($bat_file);
}
           
//
// Start the process in the background
//
$exe = "start /b ".$bat_filename;
if(
pclose(popen($exe, 'r')) ) {
    return
true;
}
return
false;
?>

In my case the file names of the .bat and .log files weren't always the same, so I needed a dynamic way to create the .bat file. The output from the php command is saved to the log file with the >> command. All prints and errors are stored there. At a later time you can open the log file and see what happened.
up
1
cyberlot at cyberlot dot net
21 years ago
The below code works for both way processing ;) Have fun folks

<?php
    system
("mkfifo pipeout");
  
$pipe = popen("./nwserver -module Chapter1E > pipeout","w");
  
$pipeout = fopen("pipeout", "r");
   while (
$s = fgets($pipeout,1024)) {
    echo
$s;
   }

?>
up
1
erco at seriss dot com
5 years ago
Another workaround for using popen() with "w" mode so that the stdout of the command reaches the browser:

An easy solution is to have two php scripts; "real.php" with the popen($cmd, "w") command in it, the other being "wrapper.php", a one liner that simply invokes system("php real.php");

Invoking "wrapper.php" from the browser allows the popen($cmd,"w") in "real.php" to work as expected, such that stdout of $cmd reaches the browser. If you try to skip the wrapper and just run "real.php", stdout of $cmd is lost to /dev/null.
up
0
mrjake2
13 years ago
If you are running in a chroot'ed environment on Debian "Squeeze", this command won't work; there is a problem with the kernel code that popen() eventually calls.

Note that pecl makes heavy use of this command, so if you are running in this environment you will need to install the pecl extension from source instead.
up
0
atampone at NOSPAMFORME dot trdsupra dot com
18 years ago
If you want to fork a process under windows, this is the function to use.  I created a batch file called runcmd.bat with the following line

start %1 %2 %3 %4

then I have the folowing function

<?php
define
('RUNCMDPATH', 'c:\\htdocs\\nonwebspace\\runcmd.bat');

function
runCmd($cmd) {
   
$externalProcess=popen(RUNCMDPATH.' '.$cmd, 'r');
   
pclose($externalProcess);
}   
?>

with this, doing something like

<?php runCmd('php.exe printWorkOrder.php 3498'); ?>
will launch php.exe outside of apache and allow the script calling the runCmd() function to continue without waiting for the command line process to return.  The process will run under the same user account that Apache (or whatever webserver you're running) is running under, so make sure it has permissions to do whatever you need to do.  Also, make sure that the batch file has enough %n s in order to pass all the command line variables that you might need to pass.

Special thanks to kicken from the devshed forums for coming up with the idea.
up
0
http://vmlinuz.nl/about/contact/
21 years ago
From the popen linux programmers manual:

"The  command  argument  is  a pointer to a null-terminated string containing a shell command line.  This  command  is passed  to  /bin/sh  using the -c flag."

Since php uses this popen function, you need to be sure /bin/sh exists. This file may not exist in chroot()ed environments.
up
0
linuxdude010 at yahoo dot com
21 years ago
I had all kinds of trouble encrypting a message with PGP, but I finanlly got it to work.  The trick was to 'chmod o+r pubring.pkr' so that the apache server could read the public keys!!!  Then, this function worked fine:

<?PHP
function pgp_encrypt($keyring_location, $public_key_id, $plain_text) {

       
$key_id = EscapeShellArg($public_key_id);
       
putenv("PGPPATH=$keyring_location");

       
// encrypt the message
       
$pipe = popen("pgpe -r $key_id -af", "r");              
       
fwrite($pipe, $plain_text);
       
$encrypted_text = '';
        while(
$s = fgets($pipe, 1024)) {
               
// read from the pipe
               
$encrypted_text .= $s;
        }
       
pclose($pipe);

        return
$encrypted_text;
}

$message = pgp_encrypt("/home/username/.pgp", "to@domain.com", "dummy text to be encrypted");
print
nl2br($message);

?>
up
-2
Cride5
18 years ago
Here is a nice little script for monitoring your http access log.

<?php

$handle
= popen("tail -f /etc/httpd/logs/access.log 2>&1", 'r');
while(!
feof($handle)) {
   
$buffer = fgets($handle);
    echo
"$buffer<br/>\n";
   
ob_flush();
   
flush();
}
pclose($handle);

?>

----
www.eviltree.co.uk
www.solidsites.co.uk
www.mongbong.com
up
-1
PGP Dude
18 years ago
I should say, my host uses a modified form of safe mode, so I don't know if that might have caused a problem with "popen" as opposed to "proc_open".  With safe mode enabled, all words following the initial command string are treated as a single argument. Thus, echo y | echo x becomes echo "y | echo x".  [Because of this,] LinixDude010's srcipt did not work for me.  Seems wrong to read and write with popen, according to the manual.

The script produced pgp text, but there was something wrong with the text and I could not decode it.

This replacement script, using proc_open, which can read and write, DOES work:

<?php
function pgp_encrypt($keyring_location, $public_key_id, $plain_text) {
 
$encrypted_text='';
 
$key_id = EscapeShellArg($public_key_id);
 
putenv("PGPPATH=$keyring_location");

 
// encrypt the message
 
$descriptorspec = array(
   
0 => array("pipe", "r"),  // stdin
   
1 => array("pipe", "w"),  // stdout
   
2 => array("pipe", "w")   // stderr ?? instead of a file
 
);
 
$process = proc_open("pgpe -r $key_id -af", $descriptorspec, $pipes);
  if (
is_resource($process)) {
   
fwrite($pipes[0], $plain_text);
   
fclose($pipes[0]);
    while(
$s= fgets($pipes[1], 1024)) {
         
// read from the pipe
         
$encrypted_text .= $s;
    }
   
fclose($pipes[1]);
   
// optional:
   
while($s= fgets($pipes[2], 1024)) {
     
$encrypted_text.= "\n<p>Error: $s</p>\n";
    }
   
fclose($pipes[2]);
  }
  return
$encrypted_text;
}

$message = pgp_encrypt("/home/username/.pgp", "to@domain.com", "dummy text to be encrypted");
print
nl2br($message);

?>
up
-3
ajv-php at erkle dot org
21 years ago
I noticed that some of the examples above seem to advocate passing unencrypted data to gpg via the pipe shell escape, in the absence of a bi-directional popen (on some OSes).

The approach I've taken is similar to:

<?php
  $prefix
= 'example';
 
$command = '/usr/local/bin/gpg --encrypt --armor --no-tty --batch --no-secmem-warning --recipient "joe.soap@example.com"';
 
$tmpfile = tempnam('/tmp', $prefix);
 
$pipe = popen("$command 2>&1 >$tmpfile", 'w');
  if (!
$pipe) {
   
unlink($tmpfile);
  } else {
   
fwrite($pipe, $plaintxt, strlen($plaintxt));
   
pclose($pipe);
   
$fd = fopen($tmpfile, "rb");
   
$output = fread($fd, filesize($tmpfile));
   
fclose($fd);
   
unlink($tmpfile);
  }
  return
$output;
?>

This means that unencrypted information is not passed via a (potentially readable) shell command, and only encrypted information gets stored on disc.
up
-4
php at keithtyler dot net
14 years ago
Note that you *have* to do a read on the handle before you can feof(), even if the command outputs nothing! So..

<?php
$f
=popen("sleep 2","r");
while (!
feof($f)) {}
pclose($f);
print
"done";
?>

will never finish.
up
-4
nricciardi at mindspring dot com
22 years ago
ive tried using popen using bidirectional pipes without working for obvious reasons, but i managed to create a simple script that managed to take care of the problem.  This example is for gpg encryption.

<?php
   $message
= "this is the text to encrypt with gpg";
  
$sendto = 'Dummy Key <another@fake.email>';

  
system("mkfifo pipein");
  
system("mkfifo pipeout");
  
system("gpg --encrypt -a -r '$sendto' > pipeout < pipein &");
  
$fo = fopen("pipeout", "r");
  
$fi = fopen("pipein", "w");
  
fwrite($fi, $message, strlen($message));
  
fclose($fi);
   while (!
feof($fo)) {
     
$buf .= fread($fo, 1024);
   }
   echo
$buf;
  
unlink("pipein");
  
unlink("pipeout");
?>

If anyone has a better way of doing this I would love to see it.
up
-2
betchern0t
16 years ago
Care needs to be taken in the case of long running child processes. Say you want to run tail -f /var/log/messages or in my case burn dvds. If you have a busy wait, Apache2 can sit towards 100%cpu and steadily grow memory. In my case I crashed the server after about an hour and 90% of the dvd burned. During that time apache had consumed a gig of swap.

Offending code - don't copy:

<?php
        $ThisCommand
= sprintf("%s %s",COMMAND,$ThisFile);
       
$fp=popen($ThisCommand,"r");
        while (!
feof($fp)) {
               
set_time_limit (20);
               
$results = fgets($fp, 4096);
                if (
strlen($results) == 0) {
                  
// stop the browser timing out
                  
echo " ";
                  
flush();
                } else {
                  
$tok = strtok($results, "\n");
                   while (
$tok !== false) {
                        echo
htmlentities(sprintf("%s\n",$tok))."<br/>";
                       
flush();
                       
$tok = strtok("\n");
                   }
                }
        }
       
pclose($fp);
?>

to go from zero memory and 100% cpu  to negligible memory and negligible cpu add a sleep.

<?php
       
while (!feof($fp)) {
               
set_time_limit (20);
               
$results = fgets($fp, 256);
                if (
strlen($results) == 0) {
                  
// stop the browser timing out
                  
echo " ";
                  
flush();
                } else {
                  
$tok = strtok($results, "\n");
                   while (
$tok !== false) {
                        echo
htmlentities(sprintf("%s\n",$tok))."<br/>";
                       
flush();
                       
$tok = strtok("\n");
                   }
                }
               
// avoid a busy wait
               
sleep(1);

        }
?>

I think the continued banging of the space to keep the browser awake triggered some issues in apache.
up
-3
Anonymous
21 years ago
Here is a workaround for not having bidirectional pipes in php.

If you have bidirectional pipe support, don't bother with this.

The trick here is to send the input on the command line to the target application.  In particular I wanted to use openssl without using temp files or named pipes.  This solution should also be thread/process safe.

This does work on Linux (RedHat 7).

<?php
function filterThroughCmd($input, $commandLine) {
 
$pipe = popen("echo \"$input\"|$commandLine" , 'r');
  if (!
$pipe) {
    print
"pipe failed.";
    return
"";
  }
 
$output = '';
  while(!
feof($pipe)) {
   
$output .= fread($pipe, 1024);
  }
 
pclose($pipe);
  return
$output;
}

# example:
print filterThroughCmd("hello", "cat");
# Piping to cat has the effect of echoing your input.
?>
up
-4
Michel Machado
20 years ago
Yet another workaround for not having bidirectional pipes in php.

<?php
$Cmd
=
"bc 2>&1 << END\n" .
"100+221\n" .
"1+3*3\n" .
"quit\n" .
"END\n";

$fp = popen($Cmd, 'r');
$read = fread($fp, 1024);
echo
$read;
pclose($fp);
?>
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