Replace a string in shell script using a variable

Question

I am using the below code for replacing a string inside a shell script.

echo $LINE | sed -e \'s/12345678/\"$replace\"/g\'

but it\'s getting

Answer 1

Single quotes are very strong. Once inside, there's nothing you can do to invoke variable substitution, until you leave. Use double quotes instead:

echo $LINE | sed -e "s/12345678/$replace/g"