The comment symbol for Unix scripts is typically “#”. You can use the same concept for files for other programming languages. My vi commands below use the “#” symbol.

If you want to comment 5 lines in a file -

1. Go to the first line you want to comment
2. Make sure you are in the command mode. (Hit ESC).
3. Now type the following “:.,+N-1 s/^/#/g”, Where N is the number of lines you want to comment.

In this case it would be -

:.,+4 s/^/#/g

You can also comment till a unique word in a file. For instance here is a snippet of a file -

line one  
line two  
line three  
line four  
line five

Suppose you want to comment from line two till line four. Go to the beginning of “line two” and type the following after you are in the command mode

:.,/line four/ s/^/#/g