VIM personal cookbook

vim-cookbook.txt

to modify lines=>
:<start_line_number>,<end_line_number>s/<regex>/<text>



for example to add comment on start from line 5 to 10:   ":5,10s/^/#"
to undo this:  ":5,10s/^#//"



to copy specific line
1. Move the cursor to the line you want to copy.
2. Press yy to copy the entire line.
3. Move the cursor to the position where you want to paste the copied line.
4. Press p to paste the copied line after the cursor or P to paste it before the cursor.

OR

:<line_number>copy .

For example:
:5copy .



to copy last line:
1. Move the cursor to the line you want to copy from.
2. Press Shift + yy to copy the line.
3. Move the cursor to the position where you want to paste the copied line.
4. Press p to paste the copied line after the cursor or P to paste it before the cursor.

OR 

":-1t."