I open a file named mysql.info :
cat mysql.info | less

it lists some menu, part of the menu like this:
* Menu:

* preface:: Preface and Notes
* introduction:: General Information
* installing:: Installing and Upgrading MySQL
* tutorial:: Tutorial
* programs:: MySQL Programs
* server-administration:: MySQL Server Administration
* backup-and-recovery:: Backup and Recovery
* optimization:: Optimization
* language-structure:: Language Structure
* globalization:: Globalization
* data-types:: Data Types
* functions:: Functions and Operators
* sql-syntax:: SQL Statement Syntax
* storage-engines:: Storage Engines
* ha-overview:: High Availability and Scalability
* replication:: Replication

and i want to jump to "* server-administration::" to , how to do it?

thanks.

You don't have to use cat; you can straight away use less

To search in less, press '/' and type your search term; next press <enter>

Is that what you're looking for? Else please rephrase the question.

how to rephrase the question? I only just get the menu item.

I mean how to repeat the search after I found the first one?

'/' slash again and press <enter> if you want to search for the same string

The dime should have fallen slightly earlier. Where did you get the file from? I guess it was a mysql.info.gz that you've extracted.

However those files are supposed to be read with the info command. E.g. info mysql reads and displays the contents of mysql.info.gz

I'm not a regular user of the info command, so not familiar with it. Press <tab> (that is, the tab key) will take you to the menu entries (the cursor will be on the '*' at the beginning of the line. Press <enter> to navigate to (read: display) the selected item.

I don't know how to get back to the main menu.

OK, just found that you can get some help while in info. Simply press 'h' and it shows how to navigate (amongst other things); you can go back by pressing 'u' (up one level).

Yes, it works usingng "info mysql.info", thank you all.