Read each line and send it to the output file, preceded by line numbers. If the input file is

Mary had a little lamb

Whose fleece was white as snow.

And everywhere that Mary went,

The lamb was sure to go$!$

then the program produces the output file

$/*1*/$ Mary had a little lamb

$/*2*/$ Whose fleece was white as snow.

$/*3*/$ And everywhere that Mary went,

$/*4*/$ The lamb was sure to go$!$