I want to find the file names those who contain a perticular pattern say"hakkinen".

Use grep, read the man page.

Edit: sorry, misread the question, use find as era mentioned.

Regards

grep is for looking at the contents of a file..

If all the files are in the current directory, echo *hakkinen* or ls *hakkinen* or anything *hakkinen* -- read the manual for your shell for more on wildcards.

If you want to find files in any directory (or any directory which is a subdirectory of a particular directory) the find command is the correct choice.

To search all mounted disks, use / instead of /path/to/dir

This is a very basic use case and is probably featured as an example in your local manual page for find

Use find / -iname "filename"

I would use :

find / -iname "*hakkinen*"