Restrict Crontab job between a particular interval

I have a ruby file and I need to run it once in every 3 hours. This code works fine:

27 */3 * * * /path/to/ruby -rubygems /path/to/ruby_file.rb

And I don't want this file to开发者_开发知识库 run between midnight 12.00 to morning 8.00

How can I set it?

27 9-23/3 * * * should work on most modern variants of Unix.

27 9-23/3 * * * /path/to/ruby -rubygems /path/to/ruby_file.rb

should do the trick.

A good summary of it all can be found in this wikipedia article.

*/15    10-20   *       *       *       /usr/bin/php /tmp/myscript.php

*/6     6-9,21-23,0-2   *       *       *       /usr/bin/php /tmp/myscript.php

More complex cron for you my friend. Notice: cron do not jump over 23-0

2-10/4 like 2,8 or 2,6,10 ?

I think the seconds