See first line in a very large file

$ head -n 1 filepath

Explanation

head [OPTION]... [FILE]... – Print the first 10 lines of each FILE to standard output. With more than one FILE, precede each with a header giving the file name. With no FILE, or when FILE is -, read standard input. Arguments:

• -n, --lines=[-]NUM – print the first NUM lines instead of the first 10; with the leading -, print all but the last NUM lines of each file.