The ESC key problem when you putty a linux machine

You are under vi or vim and, after some edit of the file, try to exit. ESC key doesn't work.
Instead of ESC, press ctrl+[

That's all. Enjoy!

How to change vnc server password

Shortly:

su - name_of_the_user    

(vnc server has different settings for different users)

vncpasswd

sudo service vncserver restart

or 

su -
service vncserver restart

ORA-00119: invalid specification for system parameter REMOTE_LISTENER ORA-00132: syntax error or unresolved network name 'name_of_scan:1521'

When you try to startup a cluster database:

ORA-00119: invalid specification for system parameter REMOTE_LISTENER 
ORA-00132: syntax error or unresolved network name 'name_of_scan:1521'

This issue appears, mostly, after some cluster problems, solved by network reconfigurations, etc.

The workaround is very easy. 
First of all, you have to notice there are two sqlnet.ora files. One of them, in the grid home. The second, in the database home.
For the sake of our problem here, important is the bellow database home one.

So, run the db environment script, go to $TNS_ADMIN folder and observe the lack of the EZCONNECT method in the sqlnet.ora file. Be sure it will be:

cd $TNS_ADMIN
vi sqlnet.ora

....
NAMES.DIRECTORY_PATH= (TNSNAMES, EZCONNECT)
 .....

Then, everything will work like a charm. Enjoy!