Usefull vi commands

I prefer to work with vi to modify config files. I used to forget the commands to interact with vi all the time so I decided to write them down. These are the ones I mostly use:

9ylcopy nine characters from cursor position, e.g à 192.168.1 will be copied
ppaste what you have copied
xdelete character
:wqwrite and quit (save and close)
/search_stringsearch for string search_string
dddelete line
10dddelete 10 lines
yycopy line
10yycopy 10 lines