Linux: vnc via ssh

remind myself:
1. start 'vncserver -name X' on server computer (that you try to connect by ssh)
Note: X is a session name which is defined in the file: ~/vnc/xstartup
2. ssh -L 5902:localhost:5901 YourAccountName@YourServerID(or hostname) in one local terminal
3. vncviewer localhost:5902 in your another local terminal