Rules
Add one rule per crawler group.
Generate a valid robots.txt file in seconds. Add allow and disallow rules per user-agent, plus your sitemap URL.
Add one rule per crawler group.
Robots.txt sits at your domain root and tells well-behaved crawlers which paths they may fetch. Each block names a user-agent (or * for all bots) followed by Allow and Disallow rules. It is a request, not a lock: major search engines honor it, but malicious bots ignore it.
Blocking /admin/, /cart/ and search-result pages keeps crawlers on content that matters. Allowing everything with Disallow: (empty) is the default open posture. Adding your sitemap URL at the bottom points crawlers at the full page list in one step.