how to copy particular extension files in to other directory.

It will vary from job to job and site to site, but in general:

- Maintain availability and security of systems under their control.
- Deploy and upgrade software as required.
- Possibly create and manage user accounts, if these are not handled centrally by another team.
- Monitor logs for any signs of trouble.
- Maintain system back-ups as required by availability, policy, and regulatory requirements.

This is just a basic, broad list. I suggest you read the :system administrator" article on Wikipedia and see if you can formulate some more specific questions.

Once go through this post:
http://www.linuxquestions.org/questi...9/#post4850520
It will be very helpful for you.
Good luck!

At my job, the system admin is responsible for maintaining all aspects of the system- including, but not limited to, in making sure everything is up to date, servers have enough space, installing new raids when necessary, making sure system is always operational and fixing it promptly when it goes down, adding new users and maintaining their accounts, deleting terminated users.... the list could go on almost forever. But yes, every place of business will have a different job description for it, you just need to know the basics by heart, and if/when you get a job, you should get on the job training to that company's specific admin responsibilities.

Don't forget documenting the systems