Unix operating system

[Joseph Koshy]

FreeBSD specific answers follow:

sh> How can I download Unix operating system?

Downloadable installation media for FreeBSD are linked
to from here:

http://www.freebsd.org/where.html

You should also read the 'Getting started' part of
the FreeBSD Handbook:

http://www.freebsd.org/doc/en_US.ISO8859-1/books/handbook/getting-started.html

sh> How can I study unix by online?

There are a large number of tutorials covering
various aspects of FreeBSD available on the
internet.  In addition there are freely downloadable
books such as Greg Lehey's "The Complete FreeBSD" :
http://www.lemis.com/grog/Documentation/CFBSD/

sh> If I study after finish can I get certificate?

There is an effort ongoing to define a certification
standard for the BSD family of operating systems.  Please
visit http://www.bsdcertification.org/.

-- 
FreeBSD Volunteer,     http://people.freebsd.org/~jkoshy/