Deprecate backend.inc in favor of a new site-process library

includes/drush.inc

@@ -177,10 +177,6 @@ function drush_get_global_options($brief = FALSE) {
  * (e.g. unlink() and other file system functions) so that can be suppressed
  * if the simulation mode is enabled.
  *
- * Important:  Call @see drush_op_system() to execute a shell command,
- * or @see drush_shell_exec() to execute a shell command and capture the
- * shell output.
- *
  * @param $callable
  *   The name of the function. Any additional arguments are passed along.
  * @return

src/Commands/core/NotifyCommands.php

@@ -2,9 +2,9 @@
 namespace Drush\Commands\core;
 
 use Consolidation\AnnotatedCommand\CommandData;
+use Consolidation\SiteProcess\Util\Escape;
 use Drush\Commands\DrushCommands;
 use Drush\Drush;
-use Symfony\Component\Config\Definition\Exception\Exception;
 use Webmozart\PathUtil\Path;
 
 class NotifyCommands extends DrushCommands
@@ -88,9 +88,10 @@ public static function shutdownSendText($msg, CommandData $commandData)
             }
         }
 
-        if (!drush_shell_exec($cmd, $msg)) {
-            throw new \Exception($error_message . ' ' . dt('Or you may specify an alternate command to run by setting notify:cmd in a drush.yml file'));
-        }
+        // Keep backward compat and prepare a string here.
+        $cmd = sprintf($cmd, Escape::forSite(Drush::aliasManager()->getSelf(), $msg));
+        $process = Drush::process($cmd);
+        $process->mustRun();
 
         return true;
     }