Temporarly prevent a website of being indexed by robots?

How do I temporary prevent a website from being indexed by web robots (Google, etc.)?

Many thanks,

Create a plain text file in the webserver root named robots.txt with this content:

User-Agent: *
Disallow: /

Crawlers which honor this will not index your site.

You should also use

<meta name="robots" content="noindex,nofollow">

in your head

Top. Thanks.