Using sed replace line in file with another file

Question

I have a very large tab delimited file, I would like to replace a single line in this file with another. As the line has >100 columns, a simple sed \'s/find/replace/\' is not de

Answer 1

From @Aaron

sed "s/^.*find.*$/$(cat newline.txt)/" infile.txt

Where find is a unique string in infile.txt that returns a single line, the line is then replaced by newline.txt