Is there a way to define the prefix of a single table ?

No, it is not possible to share the same table wp_post with different prefix wp_ and wp2_. There should be two tables in the DB, wp_post and wp2_post.

Than how can i make it possible for them to share the content ?

Are you installing the 2 wordpress in same host?
If yes, then you have to create 2 tables with wp and wp2_.

Yes 2 wordpress same host ,
I know that i can have them share same database but different prefix,
What i want to achieve is both sites have the same content .
I am trying to define table wp_option to be different on those wordpress and all the other tables to be the same .
So when i have 2 installations
sharing the same tables but only option table to be different
they will have different url and home links.
The content will be the same and the url different.

If you are not frequently updating your posts, you can generate SQL dump without wp_option table and restore it to another database. I am not sure the way you are going to use will be successful.

Problem is ,
this is not an optimal solution .
This is what i am using but its not what i want to do
for the rest of my “posting”.

Then you can write a PHP script to dump your tables and then import them to another database and set up a cron to execute it automatically.

That is an awesome solution my friend.

I’m going to use php , ssh and bash to do this .
What is needed to use ssh in php ?
So i can use bash scripts to do what i am trying to.

Practically I never did it but following link may help you:

https://davidwalsh.name/backup-mysql-database-php

Thanks mate.