error_log - PHP code example

PHP Function Error_Log

Error logging is an important aspect of PHP development. It allows for error tracking and troubleshooting, allowing developers to find and fix issues before they become more serious. It’s also a great tool for debugging, providing a trail back to where the error originated.

One of the most useful tools for logging errors is the built-in php function error_log. This function enables you to log messages for errors and other exceptions in a customized way that aligns with your specific needs.

The error_log() function takes a message and an integer that signals the error type as its first two parameters. The second parameter is the error message itself, which can be set using a number of pre-defined constants.

These values signal different types of errors: E_ERROR – fatal errors that terminate script execution (e.g., calling nonexistent functions or running out of memory). E_WARNING – runtime warnings that don’t terminate script execution (e.g., a syntax error in an expression).

You can also use the syslog() function to send errors directly to the system logger, which is useful for centralized logging. However, this is less recommended, as you’ll likely want to customize the logging information.

For example, you may want to limit the maximum length of logged errors and also choose a location for error log files, which must be writable by the web server. Lastly, you’ll need to decide whether or not to show the logged messages on screen. The syslog() function has its own parameters for these settings, which are described in the documentation here.

error_log example

return $this->errorLog($message, $this->messageType);
    }

    /** * Extracted call to `error_log()` in order to be tested. * * @codeCoverageIgnore */
    protected function errorLog(string $message, int $messageType): bool
    {
        return error_log($message, $messageType);
    }
}

function debug_fwrite( $fp, $message ) {
    _deprecated_function( __FUNCTION__, '3.4.0', 'error_log()' );
    if ( ! empty( $GLOBALS['debug'] ) )
        error_log( $message );
}

/** * Close the debugging file handle. * * @since 0.71 * @deprecated 3.4.0 Use error_log() * @see error_log() * * @link https://www.php.net/manual/en/function.error-log.php * * @param mixed $fp Unused. */

    }

    function map_attrs($k, $v) {
        return "$k=\"$v\"";
    }

    function error( $errormsg, $lvl = E_USER_WARNING ) {
        if ( MAGPIE_DEBUG ) {
            trigger_error( $errormsg, $lvl);
        } else {
            error_log( $errormsg, 0);
        }
    }

}

if ( !function_exists('fetch_rss') ) :
/** * Build Magpie object based on RSS from URL. * * @since 1.5.0 * @package External * @subpackage MagpieRSS * * @param string $url URL to retrieve feed. * @return MagpieRSS|false MagpieRSS object on success, false on failure. */

if(!$fp) {
            $this->ERROR = "POP3 connect: " . _("Error ") . "[$errno] [$errstr]";
            unset($this->FP);
            return false;
        }

        socket_set_blocking($fp,-1);
        $this->update_timer();
        $reply = fgets($fp,$this->BUFFER);
        $reply = $this->strip_clf($reply);
        if($this->DEBUG)
            error_log("POP3 SEND [connect: $server] GOT [$reply]",0);
        if(!$this->is_ok($reply)) {
            $this->ERROR = "POP3 connect: " . _("Error ") . "[$reply]";
            unset($this->FP);
            return false;
        }
        $this->FP = $fp;
        $this->BANNER = $this->parse_banner($reply);
        return true;
    }

    function user ($user = "") {

$log_error = false;
            }

            $log_file = @ini_get('error_log');
            if (!empty($log_file) && ('syslog' !== $log_file) && !@is_writable($log_file))
            {
                $log_error = false;
            }

            if ($log_error)
            {
                @error_log("$note: $message in $file on line $line", 0);
            }
        }

        return $message;
    }

    public static function fix_protocol($url, $http = 1)
    {
        $url = SimplePie_Misc::normalize_url($url);
        $parsed = SimplePie_Misc::parse_url($url);
        if ($parsed['scheme'] !== '' && $parsed['scheme'] !== 'http' && $parsed['scheme'] !== 'https')
        {

$message = str_replace("{{$key}}", $val, $message);
                    } elseif ($val instanceof \DateTimeInterface) {
                        $message = str_replace("{{$key}}", $val->format(\DateTimeInterface::RFC3339), $message);
                    } elseif (\is_object($val)) {
                        $message = str_replace("{{$key}}", '[object '.get_debug_type($val).']', $message);
                    } else {
                        $message = str_replace("{{$key}}", '['.\gettype($val).']', $message);
                    }
                }
            }

            error_log(sprintf('%s [%s] %s', date(\DateTimeInterface::RFC3339), $level, $message));
        }
    }
}

throw new InvalidArgumentException(sprintf('The log level "%s" does not exist.', $level));
        }

        if (self::LEVELS[$level] < $this->minLevelIndex) {
            return;
        }

        $formatter = $this->formatter;
        if ($this->handle) {
            @fwrite($this->handle, $formatter($level, $message, $context).\PHP_EOL);
        } else {
            error_log($formatter($level, $message, $context, false));
        }

        if ($this->debug && $this->requestStack) {
            $this->record($level, $message, $context);
        }
    }

    public function getLogs(Request $request = null): array
    {
        if ($request) {
            return $this->logs[spl_object_id($request)] ?? [];
        }

/** * Log debugging info to the error log. * * Enabled when WP_DEBUG_LOG is enabled (and WP_DEBUG, since according to * core, "WP_DEBUG_DISPLAY and WP_DEBUG_LOG perform no function unless * WP_DEBUG is true), but can be disabled via the akismet_debug_log filter. * * @param mixed $akismet_debug The data to log. */
    public static function log( $akismet_debug ) {
        if ( apply_filters( 'akismet_debug_log', defined( 'WP_DEBUG' ) && WP_DEBUG && defined( 'WP_DEBUG_LOG' ) && WP_DEBUG_LOG && defined( 'AKISMET_DEBUG' ) && AKISMET_DEBUG ) ) {
            error_log( print_r( compact( 'akismet_debug' ), true ) );
        }
    }

    public static function pre_check_pingback( $method ) {
        $pingback_args = array();
        if ( $method !== 'pingback.ping' )
            return;

        // A lot of this code is tightly coupled with the IXR class because the xmlrpc_call action doesn't pass along any information besides the method name.         // This ticket should hopefully fix that: https://core.trac.wordpress.org/ticket/52524         // Until that happens, when it's a system.multicall, pre_check_pingback will be called once for every internal pingback call.

/** * Redirects logging messages to error_log. */
class SysLogTest extends SysLog implements LoggerInterface {

  /** * {@inheritdoc} */
  protected function syslogWrapper($level, $entry) {
    $log_path = \Drupal::service('file_system')->realpath('public://syslog.log');
    error_log($entry . PHP_EOL, 3, $log_path);
  }

}

    protected function maybe_log_events_response( $message, $details ) {
        _deprecated_function( __METHOD__, '4.9.0' );

        if ( ! WP_DEBUG_LOG ) {
            return;
        }

        error_log(
            sprintf(
                '%s: %s. Details: %s',
                __METHOD__,
                trim( $message, '.' ),
                wp_json_encode( $details )
            )
        );
    }
}

return;
        }
        //Avoid clash with built-in function names         if (is_callable($this->Debugoutput) && !in_array($this->Debugoutput, ['error_log', 'html', 'echo'])) {
            call_user_func($this->Debugoutput, $str, $level);

            return;
        }
        switch ($this->Debugoutput) {
            case 'error_log':
                //Don't output, just log                 error_log($str);
                break;
            case 'html':
                //Cleans up output a bit for a better looking, HTML-safe output                 echo gmdate('Y-m-d H:i:s'), ' ', htmlentities(
                    preg_replace('/[\r\n]+/', '', $str),
                    ENT_QUOTES,
                    'UTF-8'
                ), "<br>\n";
                break;
            case 'echo':
            default:

return false;
        }

        $caller = $this->get_caller();
        if ( $caller ) {
            // Not translated, as this will only appear in the error log.             $error_str = sprintf( 'WordPress database error %1$s for query %2$s made by %3$s', $str, $this->last_query, $caller );
        } else {
            $error_str = sprintf( 'WordPress database error %1$s for query %2$s', $str, $this->last_query );
        }

        error_log( $error_str );

        // Are we showing errors?         if ( ! $this->show_errors ) {
            return false;
        }

        wp_load_translations_early();

        // If there is an error then take note of it.         if ( is_multisite() ) {
            $msg = sprintf(

function logIO( $io, $msg ) { // phpcs:ignore WordPress.NamingConventions.ValidFunctionName.FunctionNameInvalid     _deprecated_function( __FUNCTION__, '3.4.0', 'error_log()' );
    if ( ! empty( $GLOBALS['xmlrpc_logging'] ) ) {
        error_log( $io . ' - ' . $msg );
    }
}

        //Avoid clash with built-in function names         if (is_callable($this->Debugoutput) && !in_array($this->Debugoutput, ['error_log', 'html', 'echo'])) {
            call_user_func($this->Debugoutput, $str, $this->SMTPDebug);

            return;
        }
        switch ($this->Debugoutput) {
            case 'error_log':
                //Don't output, just log                 /** @noinspection ForgottenDebugOutputInspection */
                error_log($str);
                break;
            case 'html':
                //Cleans up output a bit for a better looking, HTML-safe output                 echo htmlentities(
                    preg_replace('/[\r\n]+/', '', $str),
                    ENT_QUOTES,
                    'UTF-8'
                ), "<br>\n";
                break;
            case 'echo':
            default: