How to use sed to remove the last n lines of a file

Question

I want to remove some n lines from the end of a file. Can this be done using sed?

For example, to remove lines from 2 to 4, I can use

$ sed          


        

Answer 1

A funny & simple sed and tac solution :

n=4
tac file.txt | sed "1,$n{d}" | tac

NOTE

• double quotes " are needed for the shell to evaluate the $n variable in sed command. In single quotes, no interpolate will be performed.
• tac is a cat reversed, see man 1 tac
• the {} in sed are there to separate $n & d (if not, the shell try to interpolate non existent $nd variable)