To password protect a folder in Linux

Use the zip command:

zip -e -r "name of the new zip file" "path of the folder which has to be protected"

Eg:

If you want to protect a folder named "old" in your desktop. Just do it...

zip -e -r /home/dinesh/Desktop/new /home/dinesh/Desktop/old

[dinesh@LINUXPOINT ~]$ zip -e -r /home/dinesh/Desktop/new /home/dinesh/Desktop/old
Enter password:
Verify password:

This will create a zip file named "new.zip" in your desktop(new.zip). After that delete the folder "old".