How to get the first line of a file in a bash script?

Question

I have to put in a bash variable the first line of a file. I guess it is with the grep command, but it is any way to restrict the number of lines?

Answer 1

line=$(head -1 file)

Will work fine. (As previous answer). But

line=$(read -r FIRSTLINE < filename)

will be marginally faster as read is a built-in bash command.