password protecting directories
 

is there any why i can password protect linux under directories?
say when someone tries to execute the command

cd <directory-name>

it should ask for password

you should be setting up things such as this via access rights on the file system, preserving diredtory ownership and such. if you want a password for a certain directory i'd say maybe creating a special user who can only access that directory or such like. better though just to restrict it's access in the conventional ways.

Or use an encrypted filesystem (will decrease performance and stability though) ...