User-agent: *
Disallow: /robots.txt
What happens if you do this? Will search engines crawl robots.txt once and then never crawl it again?
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1It might cause an infinite loop and melt the internet :o) – Steve Aug 10 at 3:54
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1What's the purpose of asking this - was it done by mistake, or did you intend something else? Obviously the search engine would need to crawl your robots.txt file first, so it would likely just ignore this directive. You could of course test it with Google's robots.txt Tester, which will highlight syntax warnings and logic errors (the latter of which this would likely fall under). – dan♦ Aug 10 at 3:54
Robots.txt directives don't apply to robots.txt itself. Crawlers may fetch robots.txt even if it disallows itself.
It is actually very common for robots.txt to disallow itself. Many websites disallow everything:
User-Agent: *
Disallow: /
That drective to disallow everything would include robots.txt. I myself have some websites like this. Despite disallowing everything including robots.txt, search engine bots refresh the robots.txt file periodically.
Google's John Mueller recently confirmed that Googlebot still crawls a disallowed robots.txt: Disallowing Robots.txt In Robots.txt Doesn't Impact How Google Processes It. So even if you specifically called out Disallow: /robots.txt, Google (and I suspect other search engines) wouldn't change their behavior.
