How to embed variables in sh script?

Question

linux

All the best! There is this script:

cat /etc/passwd | grep -v ‘^*#’ | awk -F\\: ‘{print $1}’ | sed -n $FT_LINE1,$FT_LINE2p | rev | sort -r | tr ‘\n’ ‘,’

It is necessary to make so that I myself could select the lines. But I can’t insert variables into sed, I tried to write in different ways (both quotes and brackets) it doesn’t work.
How to insert variables instead of numbers here??
sed -n 1,5p

Answer 1

To refer to variables, use the following syntax:
${FT_LINE1}