Can Drush 9 be used with this core version? I have a Drupal 7 site that was not built with Composer. I have been using Drush 7 with it, but about a week ago, drush wd-show --tail stopped working, I'm not getting any output. I installed Drush 9, but I'm having difficulty configuring it. 

I created an XML file, per the example., Instructions say to put aliases in $PROJECT/drush/sites/self.site.yml but I don't have a project root with a composer.json – can I get this to work without using Composer to build my site? Or is Drush 9 depending on the Drupal site using Composer?

I'm running the local version of the site in MAMP on my Mac. I created sites/drush/sites/self.site.yml – it contains:

local:
  root: /Users/pglatz/dev/wdocs/wdocs-code/www
  uri: 'https://www.whiskerdocs-local-qa.pglatz.com/'


The command I'm using is:

$ drush9 @local --alias-path=/Users/pglatz/dev/wdocs/wdocs-code/www/sites/drush/sites --root=/Users/pglatz/dev/wdocs/wdocs-code/www


When I run it, I get the error:


  Command wd-show was not found. Pass --root or a @siteAlias in order to run Drupal-specific commands.


But I am passing --root and a site alias. Likely a dumb syntax error on my part, but I can't figure it out. What am I doing wrong? And how can I get Drush to be working properly again?
No. Drupal 7 requires Drush 8.

See https://www.drush.org/latest/install/#drupal-compatibility

Furthermore, Drush 9 can't be installed globally.

See https://www.drush.org/latest/install/