I was wondering if there is a way to comment out a set of lines in a shell script.
How could I do that? We can use /\* \*/ in other programming languages.
This is most useful when I am converting/using/modifying another script 
and I want to keep the original lines instead of deleting.

It seems a cumbersome job to find and prefix # for all the lines which are not used.

Lets say there are 100 lines in the script in consequent lines which are not to used.
I want to comment them all out in one go. Is that possible?