I have just started using Vim for writing small scripts while doing CTFs so this will have things that I am learning with time.
duplicate a line: :t.
Copy paste are simple:
Shift+CTRL+C
- copy
Shift+CTRL+V
- paste
quit
:qa!
visual mode:
v
to get into visual mode - this is just for characters
V
- this is for line mode
Ctrl+v
- Visual block mode
Use arrow keys to select the text.
Shift+$ - to completely select the word.
Y - yank(copy)
d - delete
p - paste
u - undo
:s/,/\r/g
Break on comma
:set number
Show line number
Select the first caracter of your block
press Ctrl+V ( this is rectangular visual selection mode)
type j
for each line more you want to be commented
type Shift-i
(like I for "insert at start")
type // (or # or " or ...)
You will see the modification appearing only on the first line
IMPORTANT LAST STEP: type Esc key, and there you see the added character appear on all lines