A site has <meta name="robots" content="index, follow" /> Then again use <meta name="robots" content="noindex, nofollow" /> Is it right for robots.txt format. Is it effect any negative issue at SEO?
Where did you get this garbage question from?!? It makes no sense whatsoever. robots.txt has nothing to do with those meta tags. I suggest you search Google/Bing/whatever and read up on the topics of robots.txt and meta robots tags. (There is lots of information out there already.)
robots.txt file is a file uploaded to your root folder and is primarily meant to give instructions to robots.Metatags give search engines data about you site. As @ryan_uk has said, the file has nothing to do with meta tags
Following is the right format. <meta name="robots" content="index, follow"> The spider will now index your whole website. The spider will not only index the first web-page of your website but also all your other web-pages. <meta name="robots" content="noindex" /> The robots meta tag in the above example instructs all search engine not to show the page in search results. The value of the name attribute (robots) specifies that the directive applies to all crawlers. To address a specific crawler, replace the robots value of the name attribute with the name of the crawler that you are addressing. Specific crawlers are also known as user-agents (a crawler uses its user-agent to request a page.) Google's standard web crawler has the user-agent name Googlebot. To prevent only Googlebot from crawling your page, update the tag as follows:
<meta name="robots" content="index, follow"> Is it the right format? can I use it. Is it SEO friendly?
What she says. by the way, if you don't really know what to write in a robots.txt file, just use any of the available generators (come in many on page optimization tools).
This will not effect your website. For more details you can see this post: http://www.shinemat.com/2012/10/robottxt-what-is-and-its-importance.html
To make it as short as possible: - all that starts with meta (tags) go only inside your html hage header - all that robots.txt is , is one file on the root of your site. They do not have any common points at all. - meta tags directives are just say some "suggestions" toward search engines to obey your tempo ... but of course they never will - the root txt file is again a bunch of "suggestions" towards search engines to treat differently various parts of your site ... but of course they never will (except maybe G) ... the bottom line is that none of these will not help much if at all on SEO.