feat: implement exists and linked subcommands

common-functions

@@ -289,6 +289,20 @@ service_info() {
   fi
 }
 
+service_is_linked() {
+  declare desc="Links a service to an application"
+  declare SERVICE="$1" APP="$2"
+  update_plugin_scheme_for_app "$APP"
+  local SERVICE_URL=$(service_url "$SERVICE")
+  local EXISTING_CONFIG=$(config_all "$APP")
+  local LINK=$(echo "$EXISTING_CONFIG" | grep "$SERVICE_URL" | cut -d: -f1) || true
+  if [[ -z $LINK ]]; then
+    dokku_log_warn "Service $SERVICE is not linked to $APP"
+    exit 1
+  fi
+  dokku_log_info1 "Service $SERVICE is linked to $APP"
+}
+
 service_link() {
   declare desc="Links a service to an application"
   declare SERVICE="$1" APP="$2"