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proc_open

(PHP 4 >= 4.3.0, PHP 5)

proc_open --  Execute a command and open file pointers for input/output

Description

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

proc_open() is similar to popen() but provides a much greater degree of control over the program execution.

PHP 5 introduces pty support for systems with Unix98 ptys. This allows your script to interact with applications that expect to be talking to a terminal. A pty works like a pipe, but is bi-directional, so there is no need to specify a read/write mode. The example below shows how to use a pty; note that you don't have to have all descriptors talking to a pty. Also note that only one pty is created, even though pty is specified 3 times. In a future version of PHP, it might be possible to do more than just read and write to the pty.

Parameters

cmd

The command to execute

descriptorspec

An indexed array where the key represents the descriptor number and the value represents how PHP will pass that descriptor to the child process. 0 is stdin, 1 is stdout, while 2 is stderr.

The currently supported pipe types are file, pipe and pty.

The file descriptor numbers are not limited to 0, 1 and 2 - you may specify any valid file descriptor number and it will be passed to the child process. This allows your script to interoperate with other scripts that run as "co-processes". In particular, this is useful for passing passphrases to programs like PGP, GPG and openssl in a more secure manner. It is also useful for reading status information provided by those programs on auxiliary file descriptors.

pipes

Will be set to an indexed array of file pointers that correspond to PHP's end of any pipes that are created.

cwd

The initial working dir for the command. This must be an absolute directory path, or NULL if you want to use the default value (the working dir of the current PHP process)

env

An array with the environment variables for the command that will be run, or NULL to use the same environment as the current PHP process

other_options

Allows you to specify additional options. Currently only suppress_errors is supported, which suppresses errors generated by this function when it's set to TRUE

Return Values

Returns a resource representing the process, which should be freed using proc_close() when you are finished with it. On failure returns FALSE.

ChangeLog

VersionDescription
5.0.0. Added the cwd, env and other_options parameters. Added support for Unix98 ptys.

Examples

Example 1. A proc_open() example

<?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
);

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

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

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

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

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

The above example will output something similar to:

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

Example 2. ptys usage

<?php
// Create a pseudo terminal for the child process
$descriptorspec = array(
   0 => array("pty"),
   1 => array("pty"),
   2 => array("pty")
);
$process = proc_open("cvs -d:pserver:cvsread@cvs.php.net:/repository login", $descriptorspec, $pipes);
if (is_resource($process)) {
   // work with it here
}
?>

Notes

Note: Windows compatibility: Descriptors beyond 2 (stderr) are made available to the child process as inheritable handles, but since the Windows architecture does not associate file descriptor numbers with low-level handles, the child process does not (yet) have a means of accessing those handles. Stdin, stdout and stderr work as expected.

Note: If you only need a uni-directional (one-way) process pipe, use popen() instead, as it is much easier to use.

See Also

popen()
exec()
system()
passthru()
stream_select()
The backtick operator

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