How to use a variable in bash between ' '

Question

I want to print the last line of a text file in shell the number of lines in my text are stored in a variable named n when I try to use sed command like this sed -n '$np' I get an error.How can I solve this problem ?

Answer 1

You would use double quotes: sed -n "${n}p" your_file.txt, but you don't need sed for this. Just use tail:

tail -n 1 your_file.txt