execute a command in php and return the captured output and streams stdin, stdout, stderr

shell_execute.php

<?php
define('VERBOSE', 1);
define('DEBUG', 1);

//-----------------------------------------------------------------------------
// required commands check
$commands = get_commands([
    'find' => 'System command: find',
    'curl' => 'https://curl.haxx.se',
    'wget' => 'https://www.gnu.org/software/wget/'
    ]);

if (empty($commands)) {
    exit;
}

//-----------------------------------------------------------------------------
// main program

debug('Commands:' $commands);
debug('Memory used:');
echo get_memory_used();
verbose('Finished.');

//-----------------------------------------------------------------------------

/**
 * Dump debug data if DEBUG constant is set
 *
 * @param  optional string $string string to output
 * @param  optional mixed $data to dump
 * @return boolean true if string output, false if not
 */
function debug($string = '', $data = '')
{
    if (DEBUG) {
        echo trim('[D ' . get_memory_used() . '] ' . $string) . "\n";
        if (!empty($data)) {
            print_r($data);
        }
        return true;
    }
    return false;
}


/**
 * Output string if VERBOSE constant is set
 *
 * @param  string $string string to output
 * @param  optional mixed $data to dump
 * @return boolean true if string output, false if not
 */
function verbose($string, $data = '')
{
    if (VERBOSE && !empty($string)) {
        echo trim('[V' .((DEBUG) ? ' ' . get_memory_used() : '') . '] ' . $string) . "\n";
        if (!empty($data)) {
            print_r($data);
        }
        return true;
    }
    return false;
}


/**
 * Get memory used MB
 *
 * @return string memory used in MB
 */
function get_memory_used()
{
    return(
        ceil(memory_get_usage() / 1024 / 1024) . '/' .
        ceil(memory_get_peak_usage() / 1024 / 1024));
}

function get_commands($requirements = [])
{
    static $commands = []; // cli command paths

    $found = true;
    foreach ($requirements as $tool => $description) {
        if (!array_key_exists($tool, $commands)) {
            $found = false;
            break;
        }
    }
    if ($found) {
        return $commands;
    }

    $errors = [];
    foreach ($requirements as $tool => $description) {
        $cmd = cmd_execute("which $tool");
        if (empty($cmd)) {
            $errors[] = "Error: Missing requirement: $tool - " . $description;
        } else {
            $commands[$tool] = $cmd[0];
        }
    }

    if (!empty($errors)) {
        echo join("\n", $errors) . "\n";
    }

    return $commands;
}

/**
 * Execute a command and return streams as an array of
 * stdin, stdout, stderr
 *
 * @param  string $cmd command to execute
 * @return mixed array $streams | boolean false if failure
 * @see    https://secure.php.net/manual/en/function.proc-open.php
 */
function shell_execute($cmd)
{
    $process = proc_open(
        $cmd,
        [
        ['pipe', 'r'],
        ['pipe', 'w'],
        ['pipe', 'w']
        ], $pipes
    );
    if (is_resource($process)) {
        $streams = [];
        foreach ($pipes as $p => $v) {
            $streams[] = stream_get_contents($pipes[$p]);
        }
        proc_close($process);
        return [
            'stdin'  => $streams[0],
            'stdout' => $streams[1],
            'stderr' => $streams[2]
        ];
    }
    return false;
}


/**
 * Execute a command and return output of stdout or throw exception of stderr
 *
 * @param  string $cmd command to execute
 * @param  boolean $split split returned results? default on newline
 * @param  string $exp regular expression to preg_split to split on
 * @return mixed string $stdout | Exception if failure
 * @see    shell_execute($cmd)
 */
function cmd_execute($cmd, $split = true, $exp = "/\n/")
{
    $result = shell_execute($cmd);
    if (!empty($result['stderr'])) {
        throw new Exception($result['stderr']);
    }
    $data = $result['stdout'];
    if (empty($split) || empty($exp) || empty($data)) {
        return $data;
    }
    return preg_split($exp, $data);
}